Top Circuits Page 24
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This is a simple RF receiver mainly for low-distance digital radio receiver application. The analog output of this circuit should be connected to a schmitt-trigger signal conditioning circuit with a proper value capacitor (from collector of T3). L1 for 27Mhz....
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The tuned circuit consists of a variable capacitor and fixed air spaced coil. For the coil, I wound between 10 and 20 turns of wire on an empty tube of around 1.5 inches diameter. The turns were spaced so that the overall length was around 3 inches. The....
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Most experienced amateurs know that SSB (single side band) reception requires a receiver fitted with a product detector or BFO (beat frequency oscillator) to reinsert the missing carrier. They also know that such receivers command significantly higher prices....
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Simplicity and repeatability are featured in this 1 watt S-band amplifier design. The design uses an MRF2001 transistor as a common base, Class C amplifier. The amplifier delivers 1 watt output with 8 dB minimum gain at 24 V, and is tunable from 2.25 to 2.35....
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Numbered components are so designated for PC-board layout purposes. C5 and C8 are disc ceramic. C6 and C7 are tantalum or electrolytic. Rl, R2 and R3 are Vi W carbon composition resistors. Silver-mica capacitors may be substituted for polystyrene (P) types...
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Cl, C2, and C3 are miniature ceramic or plastic trimmers- Tl (main winding) is 0.34 µ,. Use of 11 turns of no. 24 enameled wire on a T37-10 toroid core. The antenna winding has one turn, and Ql the source winding has three turns. T2 primary consists of 11....
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The power drain is approximately 150 mA. IC1 provides a regulated 5-volt supply for the filament heater of the sensor. The gas sensitive element is connected as one arm of a resistance bridge consisting of R4, R7, R8 and the meter Ml with its associated....
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The major device in the circuit is SRI (a TGS812 toxic-gas sensor manufactured by Figaro Engineering Inc.) The gas-sensitive semiconductor (acting like a variable resistor in the presence of toxic gas) decreases in electrical resistance when gaseous toxins....
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This circuit detects an object passing in one direction but ignores it going the opposite way. Two sensors define the sense of direction. The object blocks the light to phototransistor Ql or Q2 first dependent on the direction of approach. When the object....
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A Touch On/Off Switch is desired, this circuit fills the bill. Two sensitive gate SCRs are interconnected, so that when one of the devices is turned on, the other (if on) is forced off. That toggling effect gives an on/off circuit condition for each of the....
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Correctly adjusted, the voltage on the pot wiper is slightly less than half D+ (appx. 0.47*D+) and Q1 will conduct if (D+)-(Vp)>6.2+0.7+0.7, or 0.53*(D+) > 7.6V, (D+) > 14.3V. If D+ is lower than 13.7V, Q1 will not conduct, Q2 will get driven via....
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This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to....
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This inexpensive dc supply-voltage monitor sounds a warning when the voltage falls below a preset value. It is ideal for monitoring rechargeable batteries since it draws only a few microamperes when not sounding. The voltage at which the alarm sounds is....
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This circuit simulates the sound of an American police siren. IC2 is wired as a low frequency astable that has a cycling period of about 6 seconds. The slowly varying ramp waveform on Cl is fed to pnp emitter follower Ql, and is then used to frequency....
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This adapter circuit, based on a dual four-channel analog multiplexer handles digital signals to at least 1 MHz, and analog signals at least through the audio range. The dual multiplexer's upper half selects one input for display. The lower half generates a....
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This very simple, low cost oscillator, is built with two CMOS buffer inverters, two capacitors and a variable resistance. The circuit can work with voltages ranging from 4 V up to 18 V. If Cl = C2, the frequency of oscillation.
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Amateur Radio Transmitters using valves such as 807 or1625 works well with a plate voltage between 600V to 700 Volts.The circuit described here is a full wave voltage doubler. The output voltage is twice the input voltage. For 230V AC input the output will....
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This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage...
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The 15v zener is fed via the 4K7 resistor from the input. With 0.6v across the base - emitter of the PNP transistor, this establishes a voltage of 14.4 across the 3K3, so there must be a current of nearly 4.4mA through the 3K3. This current is available to....
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R2 = (192 x Vout) - 240, where R2 in ohms, Vout is in volts and must be at between 1.2 V and 35 V. Vin should be at least 2.5V greater than Vout. Select a wall adapter with a voltage at least 2.5 V greater than your regulated output at full load. Maximum....
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This is a high quality power supply with a continuously variable stabilised output adjustable at any value between 0 and 30VDC. The circuit also incorporates an electronic output current limiter that effectively controls the output current from a few....
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This circuit can be adapted for other regulated and unregulated voltages by using different regulators and batteries. For a 15 Volt regulated supply use two 12 Volt batteries in series and a 7815 regulator. There is a lot of flexibility in this circuit...
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This circuit above uses a 13 volt zener diode, D2 which provides the voltage regulation. Aprroximately 0.7 Volts are dropped across the transistors b-e junction, leaving a higher current 12.3 Volt output supply. This circuit can supply loads of up to 500 mA.....
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In this circuit, the 7815 regulatates the positive supply, and the 7915 regulates the negative supply. The transformer should have a primary rating of 240/220 volts for europe, or 120 volts for North America. The centre tapped secondary coil should be rated....
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A truly timeless circuit. LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink. It`s ideal for just about any application. This was my first workbench power supply and I still use....
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This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage...
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The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current....
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Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldn`t find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your....
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Tendency of entry: 220V AC. Tendency of expense: 5V DC. Current of expense: 1A..
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Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to....
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This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. Let us see what we have....
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This is a very useful project for anyone working in electronics. It is a versatile power supply that will solve most of the supply problems arising in the everyday work of any electronics work shop. It covers a wide range of voltages being continuously....
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The input transformer is likely to be the most expensive part of the entire project. As an alternative, a couple of 12 Volt car batteries could be used. The input voltage to the regulator must be at least several volts higher than the output voltage (12V) so....
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Have you ever wanted to run a TV, stereo or other appliance while on the road or camping? Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC. The wattage depends on which tansistors you use for Q1 and Q2, as well as how....
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This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also....
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This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn`t add much in....
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This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will....
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This power supply is based on the LM317 Variable Regulator. The input of the regulator needs to be around 28 Volts DC and it will output a DC voltage from 1.25vdc to 25 vdc. To adjust the output voltage simply turn the 5k ohm pot. The regulator will supply....
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When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is open, the range is approximately 300-650 mA, and 0.8-2A when it is closed. The key....
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The transformer has a 240V primary and has a secondary rated 24V at 2A. The bridge rectifier contains 4 diodes, their current rating needs to be high with respect to the transformers output current; if not the current may damage the diodes. I used MR751....
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This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer...
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This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you....
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A Universal Power supply based on the L200 regulator, which includes an outboard pass transistor to boost output currents up to 4 amps...
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Two soft start power supplies. The output voltage slowly increases to the desired output..
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Features: 1.3-12.2 V, 1 A, over-current protection. This is a simple but reliable device based one of the oldest integrated voltage regulators of them all - the LM723...
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This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light. If the input voltage falls....
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SW3 is the on/off switch. It also lets you choose between the output with the current limit and the one without. SW2 provides a selection of three different limits. You can increase or decrease this number if you wish. The limits are fixed by R4, R5 &....
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There is little to be said about this circuit. All the work is done by the regulator. The 78S09 can deliver up to 2 amps continuous output whilst maintaining a low noise and very well regulated supply. The circuit will work without the extra components, but....
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A high voltage step-up DC power supply using adjustable flyback conversion...
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It is a voltage regulator that allows a 6v portable supply to be derived from the 12v car battery. You can add a 6.2V zener diode and a LED to warn you when the input supply is overvoltage. If you could find a relay that would operate from 6.2v right up to....
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This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with no spikes on the regulated supply...
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I constructed this voltage regulator to power my two way mobile radio from the car cigarette lighter circuit. It has many other uses and the voltage can easily be adjusted by the use of a potentiometer. The voltage regulator is an LM317T, and should accept....
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As Ron suggests, controlling the output voltage from a regulator can be made variable in three ways. Using a fixed reference zener diode to increase the output by the value of the zener. A variable resistor for variable output, note that a voltage less than....
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This circuit will generate a smaller DC output voltage from a larger DC input voltage.It is quick and simple to make and by changing the value of the zener diode, the circuit can be universally adapted to provide other output voltages.The circuit and all....
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This Power Supply is suitable for the Modular Burglar Alarm. However, it has other applications. It is designed to provide an output of 12-volts, with a current of up to 1-amp. In the event of mains failure, the back-up battery takes over automatically. When....
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The 5 volt regulated power supply for TTL and 74LS series integrated circuits, has to be very precise and tolerant of voltage transients. These IC`s are easily damaged by short voltage spikes. A fuse will blow when its current rating is exceeded, but....
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Although the 78xx series of voltage regulators are available with different current outputs, you can boost
the available current output with this circuit. A power transistor is used to supply extra current to the load
the regulator, maintaining a constant....
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Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer...
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Ever needed a low power 120volt AC power source for your car, van or truck? Well this circuit should do the trick for you. It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to....
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R2 sets the output voltage. The maximum current is determined by the value of R3: the over-current protection circuitry inside the LM723 senses the voltage across R3 and starts shutting the output stage off as soon as this voltage approaches 0.65 V. This way....
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With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum....
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The power supply is based on the LM317 and LM337 variable 3-terminal regulators ICs, and while it is no powerhouse, it is quite satisfactory for testing most power amps, as long as there is no speaker connected...
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If you want to try a higher voltage with your pedals, try this simple and easy voltage doubler circuit which uses an ICL7660 CMOS Voltage Converter Chip I have found that JFETs such as the J201 sound much better at 18V than they do at 9V with more clean to....
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Our programmable MP3 player has an interface to an LCD with a HD44780 controller. These are alphanumeric LCDs with one to 4 lines of text and 16 to 40 characters per line. However, these LCDs (and LCDs in general) exist in two varieties: those that require a....
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This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn`t add much in....
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I have had a lot of queries about getting a low power negative supply in cars, to power Linkwitz transform circuits and the like. There is a switchmode converter, but I must admit that it is overkill for what most people need. Another project describes how....
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No Description available...
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This is a variable voltage 1.5A supply I threw together for bench experimenting for under $10. With a 24VDC wall wart, this board can produce anywhere from 23V to 1.2V..
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Using the versatile L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt, 2 amp rated secondary, the primary winding should equal the electricity supply in your country, which is 240V here....
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You need a power supply for a project, but only have a DC adapter available, so you can`t use my AC power adapter trick (Project 05). This little project came about because a reader had just this problem, and didn`t know what he could do..
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Such supplies are often realised with dedicated integrated circuits nowadays but it`s still interesting to give a look at old designs to understand the basics...
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Preamps may in some cases use a simple regulator, with the supplies taken from the main amp power supply. This can be a problem if the main amp is of very high power, as the supply voltage will be too high for 3-terminal regulator ICs. This will also be a....
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This document describes how to construct a dual polarity linear power supply which can be configured for any positive or negative voltage between 1.2-35V. A power supply is the fundamental building block of all but the simplest of electronic devices. It....
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The major disadvantages of usual linear power supplies are high power dissipation, the size and the appropriated weight. When looking for an alternative solution, I decided to use a switch mode power supply (SMPS). The efficiency of such power supplies is....
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Since I have provided the schematic for John L Linsley-Hood`s Class-A amplifier, I felt that some readers may wish to experiment with the concept. Unfortunately, a very low ripple power supply is needed for all Class-A amps, and the most common solution is....
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Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to....
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The Greinacher doubler circuit (a) transforms a grounded AC voltage (peak voltage Up) into symmetrical DC voltages of 1x Up each, thus producing 2x Up between outputs. If the input voltage is already symmetrical (e.g. as in an Obit), the Greinacher circuit....
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The circuit is designed to provide protection to a DIY switching power supply for car amplifiers by shutting down under any or all of the three modes of protection (over voltage, under voltage and over temperature) with minimal components...
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There will be many times where it is desirable to use the P05 supply module from a higher voltage source. For example, if you want to add balanced inputs to a power amplifier, then you need a +/-15V supply, but the amp`s supply voltage will be much too high....
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This contributed project is a result of considerable collaboration between Sergio and myself, and should not be seen as necessarily a complete project in itself, but a stepping stone to understanding switching power supplies, how they work, and what you can....
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Switch on one unit, and everything else you need turns on automatically. This can save the tedium of turning on half a dozen different things, when one should be enough! This is another project created purely from necessity. In my case, it was to switch....
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As is commonly the case, this supply was born of necessity. There is absolutely nothing special about the circuit, except that as shown, it is quite capable of up to 20 Amps intermittently or 10A continuous. Simply use a bigger transformer, bridge rectifier....
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How many times have you wished that there was a simple way to turn on that sub-woofer or some other piece of audio equipment, simply by sending it a signal? This ability is fairly common in commercial subs and some other gear, but there seems to be a....
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The original version of P05 has been around for a very long time now (around 4 years), and there are some worthwhile reasons for the updates. Although the performance of the original was not lacking in any way, I decided to change to adjustable regulators.....
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For the 60W amplifier, a nominal (full load) supply of +/- 35V is required, so a 25-0-25 secondary is ideal - however, see Updates, below. The circuit for the supply is shown below, and uses separate rectifiers, capacitors and fuses for each channel. Only....
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The circuit is based on application of National Semiconductor. First is constituted by three voltage regulators LM338 [IC1-2-3] connected ``in parallel` `. The each one regulator has the possibility of giving 5 A in his output. Also exists the possibility to....
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The basic requirements than one laboratory power supply, it is to provide voltages and currents of operation that need the usual units, to have low output resistance, low noise, small ripple and good stabilization. The above requirements are covered, from....
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Proposed power supply for amplifier 100W v-mosfet [ 1 ] is what appears in the above form. It has separated supply for the various stages of supply, stage for power, stage for control, supply for preamplifier and for stage of protection. Whoever wants it can....
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This is the voltage converter to get the voltage of ±1,25-30V from the input voltage of ±35V. I am using the 3 terminal voltage regulator for the voltage to be changed in this unit. As the regulator, LM317 is used for the positive voltage and LM337 is used....
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Many times we needed a stabilized, together regulated power supply and high relatively output voltage. These specifications him it cover our circuit. It `s a circuit that can give in his exit + 40V until + 60V 3A, with simultaneous stabilization. The....
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A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist`s workbench. This circuit is not an absolute novelty, but it is simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current....
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For it`s maximum result, the final stage of the amplifier should have the proper power supply, as the flowing, currents are very high. An Class A amplifier, requires attention. These are the rules for the power supply for the Class A audio amplifier. The....
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A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist`s workbench. This circuit is not an absolute novelty, but it`s simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current....
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Using the versatile L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt, 2 amp rated secondary, the primary winding should equal the electricity supply in your country, which is 240V here....
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It is a simple circuit regulated power supply, based on the known LM 723, that drive a transistor Q1 [2N3055]. The regulation of voltage, of expense becomes with potentiometer R1 from 0v-30v DC roughly. In order to we achieve 30 V, will should the....
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The UPS is basically an ac inverter that is powered by a 12-V, lead-acid automobile battery. During power outages, it can supply several minutes of power for an average personal computer. It incorporates a crystal-controlled 60 Hz time base, so that a....
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This circuit protects microprocessor systems from "brownouts" without the expense of an uninterruptible power supply. Designed around a small 9-V nickel cadmium battery the circuit continues to provide a constant 5-V output during brownouts of up to a few....
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A dual-voltage circuitry both strikes and maintains the arc. The lamps require a starting voltage in excess of 1,000 volts. Once stabilized, the voltage drop across the lamp is near 20 volts. Power supply consists of two main sections. The first section, the....
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The WWVB signal is broadcast as a 60 kHz carrier that is AM modulated with a time code frame that is updated once per minute. The data rate is one bit per second. Along with time code information, the data frame also contains synchronization bits, calendar....
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This zero-crossing detector uses a dual LM393 comparator, and easily controls hysteresis by the reference levels which are set on the comparator inputs. The circuit illustrated is powered by +10-V power supplies. The input signal can be an ac signal level up....
This is a simple RF receiver mainly for low-distance digital radio receiver application. The analog output of this circuit should be connected to a schmitt-trigger signal conditioning circuit with a proper value capacitor (from collector of T3). L1 for 27Mhz....
The tuned circuit consists of a variable capacitor and fixed air spaced coil. For the coil, I wound between 10 and 20 turns of wire on an empty tube of around 1.5 inches diameter. The turns were spaced so that the overall length was around 3 inches. The....
Most experienced amateurs know that SSB (single side band) reception requires a receiver fitted with a product detector or BFO (beat frequency oscillator) to reinsert the missing carrier. They also know that such receivers command significantly higher prices....
Simplicity and repeatability are featured in this 1 watt S-band amplifier design. The design uses an MRF2001 transistor as a common base, Class C amplifier. The amplifier delivers 1 watt output with 8 dB minimum gain at 24 V, and is tunable from 2.25 to 2.35....
Numbered components are so designated for PC-board layout purposes. C5 and C8 are disc ceramic. C6 and C7 are tantalum or electrolytic. Rl, R2 and R3 are Vi W carbon composition resistors. Silver-mica capacitors may be substituted for polystyrene (P) types...
Cl, C2, and C3 are miniature ceramic or plastic trimmers- Tl (main winding) is 0.34 µ,. Use of 11 turns of no. 24 enameled wire on a T37-10 toroid core. The antenna winding has one turn, and Ql the source winding has three turns. T2 primary consists of 11....
The power drain is approximately 150 mA. IC1 provides a regulated 5-volt supply for the filament heater of the sensor. The gas sensitive element is connected as one arm of a resistance bridge consisting of R4, R7, R8 and the meter Ml with its associated....
The major device in the circuit is SRI (a TGS812 toxic-gas sensor manufactured by Figaro Engineering Inc.) The gas-sensitive semiconductor (acting like a variable resistor in the presence of toxic gas) decreases in electrical resistance when gaseous toxins....
This circuit detects an object passing in one direction but ignores it going the opposite way. Two sensors define the sense of direction. The object blocks the light to phototransistor Ql or Q2 first dependent on the direction of approach. When the object....
A Touch On/Off Switch is desired, this circuit fills the bill. Two sensitive gate SCRs are interconnected, so that when one of the devices is turned on, the other (if on) is forced off. That toggling effect gives an on/off circuit condition for each of the....
Correctly adjusted, the voltage on the pot wiper is slightly less than half D+ (appx. 0.47*D+) and Q1 will conduct if (D+)-(Vp)>6.2+0.7+0.7, or 0.53*(D+) > 7.6V, (D+) > 14.3V. If D+ is lower than 13.7V, Q1 will not conduct, Q2 will get driven via....
This house alarm circuit has open and closed loop sensor and has self shutdown function. The delay after trigering can be adjusted from 1 minute to 12. The delay before trigering is 13 seconds. Offcourse all this timmings can be change with litle changes to....
This inexpensive dc supply-voltage monitor sounds a warning when the voltage falls below a preset value. It is ideal for monitoring rechargeable batteries since it draws only a few microamperes when not sounding. The voltage at which the alarm sounds is....
This circuit simulates the sound of an American police siren. IC2 is wired as a low frequency astable that has a cycling period of about 6 seconds. The slowly varying ramp waveform on Cl is fed to pnp emitter follower Ql, and is then used to frequency....
This adapter circuit, based on a dual four-channel analog multiplexer handles digital signals to at least 1 MHz, and analog signals at least through the audio range. The dual multiplexer's upper half selects one input for display. The lower half generates a....
This very simple, low cost oscillator, is built with two CMOS buffer inverters, two capacitors and a variable resistance. The circuit can work with voltages ranging from 4 V up to 18 V. If Cl = C2, the frequency of oscillation. ..
Amateur Radio Transmitters using valves such as 807 or1625 works well with a plate voltage between 600V to 700 Volts.The circuit described here is a full wave voltage doubler. The output voltage is twice the input voltage. For 230V AC input the output will....
This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage...
The 15v zener is fed via the 4K7 resistor from the input. With 0.6v across the base - emitter of the PNP transistor, this establishes a voltage of 14.4 across the 3K3, so there must be a current of nearly 4.4mA through the 3K3. This current is available to....
R2 = (192 x Vout) - 240, where R2 in ohms, Vout is in volts and must be at between 1.2 V and 35 V. Vin should be at least 2.5V greater than Vout. Select a wall adapter with a voltage at least 2.5 V greater than your regulated output at full load. Maximum....
This is a high quality power supply with a continuously variable stabilised output adjustable at any value between 0 and 30VDC. The circuit also incorporates an electronic output current limiter that effectively controls the output current from a few....
This circuit can be adapted for other regulated and unregulated voltages by using different regulators and batteries. For a 15 Volt regulated supply use two 12 Volt batteries in series and a 7815 regulator. There is a lot of flexibility in this circuit...
This circuit above uses a 13 volt zener diode, D2 which provides the voltage regulation. Aprroximately 0.7 Volts are dropped across the transistors b-e junction, leaving a higher current 12.3 Volt output supply. This circuit can supply loads of up to 500 mA.....
In this circuit, the 7815 regulatates the positive supply, and the 7915 regulates the negative supply. The transformer should have a primary rating of 240/220 volts for europe, or 120 volts for North America. The centre tapped secondary coil should be rated....
A truly timeless circuit. LM317 is a versatile and highly efficient 1.2-37V voltage regulator that can provide up to 1.5A of current with a large heat sink. It`s ideal for just about any application. This was my first workbench power supply and I still use....
This dual polarity power supply is easy to build, requires few parts, and is adjustable from 0-15 volts. It is great for powering op amp circuits, as well as other circuits that require a dual supply voltage...
The fixed voltage power supply is useful in applications where an adjustable output is not required. This supply is simple, but very flexable as the voltage it outputs is dependant only on the regulator and transformer you choose. The maximum output current....
Since my page was first posted, I have received a number of emails asking about a high current power supply. I looked around, but couldn`t find one that was suitable. So, I designed this. It is a linear supply, which might have a few of you rolling your....
Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to....
This PSU has been especially designed for current-hungry ham radio transceivers. It delivers safely around 20Amps at 13.8V. For lower currents, a separate current limiting output, capable of 15ma up to a total of 20A has been added. Let us see what we have....
This is a very useful project for anyone working in electronics. It is a versatile power supply that will solve most of the supply problems arising in the everyday work of any electronics work shop. It covers a wide range of voltages being continuously....
The input transformer is likely to be the most expensive part of the entire project. As an alternative, a couple of 12 Volt car batteries could be used. The input voltage to the regulator must be at least several volts higher than the output voltage (12V) so....
Have you ever wanted to run a TV, stereo or other appliance while on the road or camping? Well, this inverter should solve that problem. It takes 12 VDC and steps it up to 120 VAC. The wattage depends on which tansistors you use for Q1 and Q2, as well as how....
This inverter circuit can provide up to 800mA of 12V power from a 6V supply. For example, you could run 12V car accessories in a 6V (British?) car. The circuit is simple, about 75% efficient and quite useful. By changing just a few components, you can also....
This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn`t add much in....
This simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input. It is therefore extremely useful for powering opamp and other circuits that require a dual voltage from a single battery. The circuit will....
This power supply is based on the LM317 Variable Regulator. The input of the regulator needs to be around 28 Volts DC and it will output a DC voltage from 1.25vdc to 25 vdc. To adjust the output voltage simply turn the 5k ohm pot. The regulator will supply....
When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is open, the range is approximately 300-650 mA, and 0.8-2A when it is closed. The key....
The transformer has a 240V primary and has a secondary rated 24V at 2A. The bridge rectifier contains 4 diodes, their current rating needs to be high with respect to the transformers output current; if not the current may damage the diodes. I used MR751....
This is a replacement power source for 1.3V mercury cells or other small batteries. It has many uses and I use this circuit in my computer to power a front panel multi adapter which has a digital thermometer...
This circuit allows you to set a limit on the maximum output current available from your PSU. It`s very useful when you power-up a project for the first time - or carry out a soak-test. By setting an upper limit on the current available from your PSU - you....
A Universal Power supply based on the L200 regulator, which includes an outboard pass transistor to boost output currents up to 4 amps...
Two soft start power supplies. The output voltage slowly increases to the desired output..
Features: 1.3-12.2 V, 1 A, over-current protection. This is a simple but reliable device based one of the oldest integrated voltage regulators of them all - the LM723...
This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light. If the input voltage falls....
SW3 is the on/off switch. It also lets you choose between the output with the current limit and the one without. SW2 provides a selection of three different limits. You can increase or decrease this number if you wish. The limits are fixed by R4, R5 &....
There is little to be said about this circuit. All the work is done by the regulator. The 78S09 can deliver up to 2 amps continuous output whilst maintaining a low noise and very well regulated supply. The circuit will work without the extra components, but....
A high voltage step-up DC power supply using adjustable flyback conversion...
It is a voltage regulator that allows a 6v portable supply to be derived from the 12v car battery. You can add a 6.2V zener diode and a LED to warn you when the input supply is overvoltage. If you could find a relay that would operate from 6.2v right up to....
This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with no spikes on the regulated supply...
I constructed this voltage regulator to power my two way mobile radio from the car cigarette lighter circuit. It has many other uses and the voltage can easily be adjusted by the use of a potentiometer. The voltage regulator is an LM317T, and should accept....
As Ron suggests, controlling the output voltage from a regulator can be made variable in three ways. Using a fixed reference zener diode to increase the output by the value of the zener. A variable resistor for variable output, note that a voltage less than....
This circuit will generate a smaller DC output voltage from a larger DC input voltage.It is quick and simple to make and by changing the value of the zener diode, the circuit can be universally adapted to provide other output voltages.The circuit and all....
This Power Supply is suitable for the Modular Burglar Alarm. However, it has other applications. It is designed to provide an output of 12-volts, with a current of up to 1-amp. In the event of mains failure, the back-up battery takes over automatically. When....
The 5 volt regulated power supply for TTL and 74LS series integrated circuits, has to be very precise and tolerant of voltage transients. These IC`s are easily damaged by short voltage spikes. A fuse will blow when its current rating is exceeded, but....
Although the 78xx series of voltage regulators are available with different current outputs, you can boost the available current output with this circuit. A power transistor is used to supply extra current to the load the regulator, maintaining a constant....
Using this circuit you can convert the 12V dc in to the 220V Ac. In this circuit 4047 is use to generate the square wave of 50hz and amplify the current and then amplify the voltage by using the step transformer...
Ever needed a low power 120volt AC power source for your car, van or truck? Well this circuit should do the trick for you. It will supply 15 watts of AC power to a device. It should power lamps, shavers, small stereos and small appliances. If you draw to....
R2 sets the output voltage. The maximum current is determined by the value of R3: the over-current protection circuitry inside the LM723 senses the voltage across R3 and starts shutting the output stage off as soon as this voltage approaches 0.65 V. This way....
With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum....
The power supply is based on the LM317 and LM337 variable 3-terminal regulators ICs, and while it is no powerhouse, it is quite satisfactory for testing most power amps, as long as there is no speaker connected...
If you want to try a higher voltage with your pedals, try this simple and easy voltage doubler circuit which uses an ICL7660 CMOS Voltage Converter Chip I have found that JFETs such as the J201 sound much better at 18V than they do at 9V with more clean to....
Our programmable MP3 player has an interface to an LCD with a HD44780 controller. These are alphanumeric LCDs with one to 4 lines of text and 16 to 40 characters per line. However, these LCDs (and LCDs in general) exist in two varieties: those that require a....
This simple circuit is a good solution to the powering a dual supply op amp from a single battery problem. The circuit simply takes a positive voltage and inverts it. It uses only one 555 timer and a few other passive components, so it doesn`t add much in....
I have had a lot of queries about getting a low power negative supply in cars, to power Linkwitz transform circuits and the like. There is a switchmode converter, but I must admit that it is overkill for what most people need. Another project describes how....
Using the versatile L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt, 2 amp rated secondary, the primary winding should equal the electricity supply in your country, which is 240V here....
You need a power supply for a project, but only have a DC adapter available, so you can`t use my AC power adapter trick (Project 05). This little project came about because a reader had just this problem, and didn`t know what he could do..
Such supplies are often realised with dedicated integrated circuits nowadays but it`s still interesting to give a look at old designs to understand the basics...
Preamps may in some cases use a simple regulator, with the supplies taken from the main amp power supply. This can be a problem if the main amp is of very high power, as the supply voltage will be too high for 3-terminal regulator ICs. This will also be a....
This document describes how to construct a dual polarity linear power supply which can be configured for any positive or negative voltage between 1.2-35V. A power supply is the fundamental building block of all but the simplest of electronic devices. It....
The major disadvantages of usual linear power supplies are high power dissipation, the size and the appropriated weight. When looking for an alternative solution, I decided to use a switch mode power supply (SMPS). The efficiency of such power supplies is....
Since I have provided the schematic for John L Linsley-Hood`s Class-A amplifier, I felt that some readers may wish to experiment with the concept. Unfortunately, a very low ripple power supply is needed for all Class-A amps, and the most common solution is....
Sometimes amateurs like to home-brew their power supplies instead of purchasing one off the shelf at any of the major ham radio retail dealers. The advantage to rolling your own power supply is that it teaches us how they work and makes it easier to....
The Greinacher doubler circuit (a) transforms a grounded AC voltage (peak voltage Up) into symmetrical DC voltages of 1x Up each, thus producing 2x Up between outputs. If the input voltage is already symmetrical (e.g. as in an Obit), the Greinacher circuit....
The circuit is designed to provide protection to a DIY switching power supply for car amplifiers by shutting down under any or all of the three modes of protection (over voltage, under voltage and over temperature) with minimal components...
There will be many times where it is desirable to use the P05 supply module from a higher voltage source. For example, if you want to add balanced inputs to a power amplifier, then you need a +/-15V supply, but the amp`s supply voltage will be much too high....
This contributed project is a result of considerable collaboration between Sergio and myself, and should not be seen as necessarily a complete project in itself, but a stepping stone to understanding switching power supplies, how they work, and what you can....
Switch on one unit, and everything else you need turns on automatically. This can save the tedium of turning on half a dozen different things, when one should be enough! This is another project created purely from necessity. In my case, it was to switch....
As is commonly the case, this supply was born of necessity. There is absolutely nothing special about the circuit, except that as shown, it is quite capable of up to 20 Amps intermittently or 10A continuous. Simply use a bigger transformer, bridge rectifier....
How many times have you wished that there was a simple way to turn on that sub-woofer or some other piece of audio equipment, simply by sending it a signal? This ability is fairly common in commercial subs and some other gear, but there seems to be a....
The original version of P05 has been around for a very long time now (around 4 years), and there are some worthwhile reasons for the updates. Although the performance of the original was not lacking in any way, I decided to change to adjustable regulators.....
For the 60W amplifier, a nominal (full load) supply of +/- 35V is required, so a 25-0-25 secondary is ideal - however, see Updates, below. The circuit for the supply is shown below, and uses separate rectifiers, capacitors and fuses for each channel. Only....
The circuit is based on application of National Semiconductor. First is constituted by three voltage regulators LM338 [IC1-2-3] connected ``in parallel` `. The each one regulator has the possibility of giving 5 A in his output. Also exists the possibility to....
The basic requirements than one laboratory power supply, it is to provide voltages and currents of operation that need the usual units, to have low output resistance, low noise, small ripple and good stabilization. The above requirements are covered, from....![Power Supply for Amlifiers [B]](uploads/133-54d133.gif "Power Supply for Amlifiers [B]")
Proposed power supply for amplifier 100W v-mosfet [ 1 ] is what appears in the above form. It has separated supply for the various stages of supply, stage for power, stage for control, supply for preamplifier and for stage of protection. Whoever wants it can....
This is the voltage converter to get the voltage of ±1,25-30V from the input voltage of ±35V. I am using the 3 terminal voltage regulator for the voltage to be changed in this unit. As the regulator, LM317 is used for the positive voltage and LM337 is used....
Many times we needed a stabilized, together regulated power supply and high relatively output voltage. These specifications him it cover our circuit. It `s a circuit that can give in his exit + 40V until + 60V 3A, with simultaneous stabilization. The....
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist`s workbench. This circuit is not an absolute novelty, but it is simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current....
For it`s maximum result, the final stage of the amplifier should have the proper power supply, as the flowing, currents are very high. An Class A amplifier, requires attention. These are the rules for the power supply for the Class A audio amplifier. The....
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist`s workbench. This circuit is not an absolute novelty, but it`s simple, reliable, "rugged" and short-proof, featuring variable voltage up to 24V and variable current....
Using the versatile L200 voltage regulator, this power supply has independent voltage and current limits. The mains transformer has a 12volt, 2 amp rated secondary, the primary winding should equal the electricity supply in your country, which is 240V here....
It is a simple circuit regulated power supply, based on the known LM 723, that drive a transistor Q1 [2N3055]. The regulation of voltage, of expense becomes with potentiometer R1 from 0v-30v DC roughly. In order to we achieve 30 V, will should the....
The UPS is basically an ac inverter that is powered by a 12-V, lead-acid automobile battery. During power outages, it can supply several minutes of power for an average personal computer. It incorporates a crystal-controlled 60 Hz time base, so that a....
This circuit protects microprocessor systems from "brownouts" without the expense of an uninterruptible power supply. Designed around a small 9-V nickel cadmium battery the circuit continues to provide a constant 5-V output during brownouts of up to a few....
A dual-voltage circuitry both strikes and maintains the arc. The lamps require a starting voltage in excess of 1,000 volts. Once stabilized, the voltage drop across the lamp is near 20 volts. Power supply consists of two main sections. The first section, the....
The WWVB signal is broadcast as a 60 kHz carrier that is AM modulated with a time code frame that is updated once per minute. The data rate is one bit per second. Along with time code information, the data frame also contains synchronization bits, calendar....
This zero-crossing detector uses a dual LM393 comparator, and easily controls hysteresis by the reference levels which are set on the comparator inputs. The circuit illustrated is powered by +10-V power supplies. The input signal can be an ac signal level up....
