New Circuits Page 204
- Page 204
-
An audio signal applied to VI is passed through the operational amplifier 741, U2. After being amplified, the output signal V2 is sampled and applied to a negative voltage doubler / rectifier circuit composed of diodes CRI and CR2, with the capacitor C1. The....
-
-
This circuit provides interferenced rejection for the CW operator. The 567 phase-locked loop is configured to respond to tones from 500 to 1100 Hz. The Schmitt trigger reduces the weighting effect caused by the output of the PLL remaining low after removal....
-
A high-frequency audio signal (15 to 25 kHz) generated by Ul is fed to buffer Ql and SPKR1. A portion is f..
-
This thing is a very nifty capacitive sensor. For you europeans, this little gem is used in north america mostly for detecting wooden beams behind drywall or plaster. I`ll take one of these over the new design any day, because these ones don`t error out....
-
The circuit provides a windshield wiper delay, dynamic braking and windshield wipers when they reach the rest position. This prevents the blades passing, which could lead them to stop at a point where they interfere with the vision of drivers. With the....
-
The XR-T5995 Speech Network is a monolithic integrated circuit specifically designed for implementing a low cost telephone circuit.
..
-
-
This circuit is used for remote photographic flash units that flash at the~ame time as the flash attached to the camera. This circuit is designed to the trigger cord or hot shoe connection of a commercial portable flash unit and triggers the unit from the....
-
Designing a high-voltage switching power supply that can produce a sustained arc can be challenging. This compact and efficient design delivers 1 kV at 20W and can withstand a continuous arcing, or short-circuit, condition (Figure 1). It uses standard,....
-
Here is a circuit that implements phase-control of heaters, adjusting their power smoothly from zero to around 95% of the rated power, keeping the room temperature to within 1 or 2 degrees, while using few components. Notice that this is entirely an AC....
-
A very simple motion transducer can be constructed using the circuit shown. The output is biased to one-half the supply voltage. This requires special interface circuitry for the signal readout. One simple method is to use a zero center meter in a bridge....
-
Initially the neon and xenon lamps are not conducting and act like a very high (almost infinite) resistance. Capacitors Cl and C4 in conjunction with DI and D2 form a voltage doubler circuit, which can charge C2 up to about 300 Vdc after several ac cycles.....
-
-
In this strobe-light, two circuits are needed; one circuit charges a capacitor placing 320 V de between the cathode and anode of the flashtube. The other circuit provides bursts of approximately 4000 V to trigger the flashtube into conduction. The....
-
A keyed power input connector, series rectifier and a shunt rectifier, both 1N4007, prevent reverse voltage from being applied to the power input. A 27 volt metal oxide varistor clamps the voltage to the 78L05 that follow it, to less than 30 volts, thus....
-
The low Rds and high peak current capability ofthe DG419 makes it ideal for discharging an·integrator capacitor. A high logic input pulse disconnects the integrator from the analog input and discharges the capacitor. ..
-
I recently prototyped a Tube Screamer type circuit to refresh my memory about the sound of this pedal. I used a borrowed TS-808 and a Pro Reverb in the mid 80s for several weeks while my modded Twin Reverb was being fixed and I remembered it sounding pretty....
-
You can use a multimeter with capacitance-measurement capability to measure the length of wire or cable to an open circuit. The capacitance of a pair of wires (or a wire to a shield) is directly proportional to the length of the wire. If you know the....
-
The circuit is quick and easy to put together and install, and tells you when battery voltage falls below the set limit as established by Rl (a 10,000-ohm potentiometer). It can indicate, via LED 1, that the battery may be defective or in need of change if....
-
Sometimes electrolytic capacitors that are stored for some time will exhibit high leakage currents..
-
The high-speed peak detector uses a highly accurate, fast s/h amplifier controlled by a highspeed comparator. The s/h amplifier holds the peak voltage, until the comparator switches the amp to its sample mode, to capture a new, higher voltage level. The....
-
The LT®3465/LT3465A are step-up DC/DC converters designed to drive up to six LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents and eliminates the need for ballast resistors. These devices integrate the Schottky....
-
The device described here does just that. The circuit connects to the doorbell circuit - taking power from the 18 VAC from the doorbell transformer and switching power to the doorbell circuit most of the day. The user interface is a pushbutton, a toggle....
-
The circuit in Figure 1 adds a soft muting switch with power-up/power-down muting to a line-level audio circuit. R4, C1, and JFET Q1 quietly ground a signal in 100 to 200 msec when you close S1 or release it when you open S1. Potentiometer R2, set to twice....
-
This circuit switches its dc/dc converter, IC1, off whenever the large filter capacitor, C6, has suffic..
-
The most amazing thing about this project is the small number of parts. My boss joked that it involves 17 cents worth of parts and 1000 dollars worth of programming. But don`t worry -- the code is free to you! That means you can build this TV pong game in a....
-
The device generates an adjustable frequency of low to medium powered IR pulses of invisible energy and must be treated with care. The portable battery pack is stepped up to 200 to 300 volts by the inverter circuit consisting of Ql, Q2, and Tl. Ql conducts....
-
This simple 10 watts audio power amplifier is designed for home-brewed purpose. It is based on an Audio Power Amplifier IC that is called TDA2030. It is a monolithic integrated circuit in Pentawatt package, intended for use as a low frequency class AB....
-
In a lot of cars, the car-radios use amplifiers that their output power does not exceed the 5W with enough distortion in the limits of power. The problem is untied with the utilisation of external amplifiers, that will have the possibility giving much....
-
This circuit was submitted by Graham Maynard from Newtownabbey, Northern Ireland. It has an exceptionally fast high frequency response, as demonstrated by applying an 100kHz squarewave to the input. All graphs were produced using Tina Pro...
-
The circuit is basically a NE555 monostable, the only major difference being its method of triggering. The trigger input is biased to a high value by the 22 ohm resistor. When the contact plates are touched, the skin resistance of the operator will lower....
-
A clever charger circuit that safely can charge any Ni-Cd battery. Offers charge current sellection, polarization detection and protection and the ability to connect many batterys in siries. Ni-Cd bateries can be recharged more than 1000 times before become....
-
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....
-
Many times we have found itself in the necessity to use a Zener diode and cannot to know the voltage of operation. Many times we cannot read the characteristics or the type that is written on her. In this case, but in different we can also use the circuit....
-
An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13,....
-
This inverter is very easy to construct, reliable, and even powerful enough to light up a 15W florescent tube (if you cool your transistor well). The only hard-to-find piece of this baby is the so-called yellow inverter transformer. It's a miniature high....
-
This circuit is based around the 555 timer circuit, used as an astable (free running) oscillator. The frequency (pitch) of the tone is set by the resistors and capacitors in the left side of the circuit. The first one is a potentiometer (variable resistor),....
-
At the heart of the whistle swatch are a pair of tone detectors, each of which is built around an LM567 tone decoder, which are supported by a minimum of additional components. This whistle switch is designed to respond to only two or more occurrences of a....
-
In these applications, a pulse input at % is differentiated by a C-R network and the negative-going edge at pin 6 causes the input comparator to trigger the timer circuit. Just as with a V-to-F converter, the average current flowing out of pin 1 is IaverAGE....
-
"Should I cut the blue wire... or the red...?" This is a very common phrase in many movies when the action hero has a bomb in front of him with little time left and he has to choose which wire to cut and stop the bomb from exploding saving millions of....
-
This page discusses the various ways that a voltage regulator can be made using two transistors. If one of these transistors is the series-pass element, then the other must be the error amplifier, so there is a distinct limit to the number of possible....
-
Robot Beacon is a rotating light. We have called it Robot Beacon as it has been designed as an addition for a robot, but it can be used for many applications.
It can be used as a mast-head beacon on a boat or as an "all-round" warning light on a bike.....
-
If the piclist is an any indication the 16f877 seems to be the new favorite hobby microcontroller, a position that used to be occupied by the 16f84/16c84. Compared to is older brethren the 16f877 has much more to offer at around twice the price. As for all....
-
The circuit will modulate the light from the LED using a crystal microphone or a loudspeaker output. To obtain the maximum range, the optical system must be efficient (see example). Either a convex lens or a concave mirror can be used to convert the LED....
-
This circuit traps a single positive pulse from a square-wave train. Following the rising edge of an input command, the pulse-out signal emits a replica of one positive pulse of the clock signal simultane ous with the clock signal"s next rising edge. The....
-
When the output is high, R3 and R4 are in parallel, and CI charges via Rl until the current in R2 equals that a..
-
This digital volume control has no pot to wear out and introduces almost no noise in the circuit. Instead, the volume is controlled by pressing UP and DOWN buttons. This simple circuit would be a great touch to any home audio project. Using a dual polariity....
-
Temperature control is achieved using the REF-02 +5 V Reference/Thermometer and a CMP-02 Precision Low Input Current Comparator. The CMP-02 turns on a heating element driver (Ql) whenever the present temperature drops below a setpoint temperature determined....
-
This bug can be attached to anything from a glider to a pot plant and you can track it with a radio.
Why track a pot plant?
The Beeper is the result of many requests for a mini tracking device and introduces a new world of tracking.
The circuit is very....
-
Fiber Optic applications require analog drivers and receivers operating in the megahertz region. This complete analog transmission system is suitable for optical communication applications up to 3 MHz. The transmitter LED is normally biased at 50 mA....
-
Ql and Q2 are general purpose transistors. The 10 K input pot is adjusted to a point just short of where Ql turns on as indicated by K pulling in. K is any 5 V reed relay. With the values shown for R (100 K) and C (47 µf), timing values from 5 to slightly....
-
This circuit has a 100 mV hysteresis which can be used in applications where very fast transition times are required at the output even though the signal is very slow. The hysteresis loop also reduces false triggering due to noise on the input..
-
This single-chip circuit adjusts its audio gain according to the ambient noise picked up by the microphone. When ..
-
The second gate (G2) of a MOSFET can be used to incorporate a crystal oscillator into the same stage as a frequency mixer. Although old hat with tubes, this scheme is seldom seen in dual-gate MOSFET circuitry. L3, 03, and XI form the crystal oscillator, and....
-
this tone generator can be used to control your robot. you will need to use the tone decoder for this. to widen the range, higher or lower - substitute a higher, or lower valued capacitor for c1. for frequencies about 5khz and 15khz, use a piezoelectric....
-
Input terminal VIN is connected to the +V line of tbe circuit that the indicator is to monitor, and the grounds of botb circuits are connected togetber. The position of potentiometer Rl"s wiper determines Q1"s base voltage. As long as the transistor....
-
Electronic scales have come into wide use and the HA-510X, as a very low noise device, can improve such designs. This circuit uses a staingauge sensing element as part of a resistive Wienbridge. An auto-zero circuit is also incorporated into this design by....
-
This circuit can detect smoke and a number of gases (CO, CO2, methane, coal gas and others) with a 10 ppm sensitivity. It uses a heated surface semiconductor sensor. Detection occurs when the gas concentration increase causes a decrease of the sensor element....
-
The PIC 12F629 and 12F675 have a factory set oscillator calibration value written to the last program memory location during manufacture. When programming the PIC the programmer software should read this value out, merge it with the program data being....
-
Anyone performing their own automobile tune-ups knows how important it is to know your engines speed. With this tachometer, you can measure your engines speed without any connections or annoying timing lights...
-
A multi wire cable tester with a separate LED for each wire. Will show open circuits, short circuits, reversals, earth faults, continuity and all with four IC`s. Designed initially for my intercom, but can be used with alarm wiring, CAT 5 cables and more...
-
The project we have chosen as our example is an RS232 to RS485 converter. This is a often needed device which can demonstrate a lot of principles of circuit design, and hopefully the finished project will be useful to some people, just as it stands. Without....
-
This document tells about one of my experiments with semiconductor laser modules. I bought one semiconductor laser for all kinds of experiments. This TIM202 module is a small (38x14x14 mm) semiconductor laser module, similar to those types used in laser....
-
Last year, I found a 31 day pendulum wall clock (dissambled) in a box of parts at a swap meet and decided to try and put it together and regulate it with a quartz crystal oscillator. The escapement part that rocks back and forth and drives the pendulum was....
-
This self-starting fixed-frequency oscillator circuit gives excellent frequency stability. R1 and C 1 comprise the frequency-determining network, while R2 provides the regenerative feedback. Diode D 1 enhances the stability by compensating for the....
-
As systems grow smaller, it becomes increasingly attractive to replace mechanical potentiometers with electronic potentiometers, which are smaller and less expensive silicon equivalents. A common interface for such devices comprises a Chip-Select, Increment....
-
The NE564 is used as an FM demodulator. The connections for operation at 5 V and 12 V are shown in Figures 21-4A and 21-4B. The input signal is ac coupled with the output signal being extracted at Pin 14. Loop filtering is provided by the capacitors at Pins....
-
This circuit is meant to be driven by a 1-MHz standard signal of a few volts amplitude. Ul through U5 are 7490 decade counter/divider and produce a division ratio of 100,000:1. Successive divisions of 10 can be tapped off, if desired, between stages. ..
-
In this application, the timer is connected in the monostable mode. The circuit is triggered with a continuous pulse train and the threshold voltage is modulated by the signal applied to the control voltage terminal at pin 5. This has the effect of....
-
The PCB is at the center of any electronic product. Literally, the enclosure surrounds the board, and figuratively, all the mathematics, the science, the software, these all run on the board. That’s why the PCB is at the center of our tools, and our company.....
-
This circuit converts a tape recorder into a completely automatic telephone conversation recording instrument that needs no external power source. Voltage at the switch terminals of tape recorder applied to a pair of Darlington-connected transistors, Ql and....
-
As a piece of test equipment, an audio oscillator has to be considered essential for anyone working in with hi-fi gear. Together with an audio millivoltmeter (as described in Project 16), and even better if you have access to an oscilloscope, you will be....
-
IR radiation from LED2 (modulated by a 1-kHz wave) is keyed by Ul, and Ql is radiated. Reflected IR energy i..
-
This AC motor speed controller can handle most universal type (brushed) AC motors and other loads up to about 250W. It works in much the same was a light dimmer circuit; by chopping part of the AC waveform off to effectively control voltage. Because of this....
-
The circuit in Figure 1 provides a safety interlock that checks the actuation of two pushbuttons before enabling a relay. When you push both buttons, the circuit actuates the relay. At that point, you can release one of the switches without the relay`s....
-
SuiperSpice`s philosophy is centered around the edit schematic, run simulation, view waveforms, probe signals, view waveforms, edit schematic cycle. All key issues have been automated. You can effortlessly modify the schematic, rerun and inspect new....
-
The circuit lowers the effective peak current of the output PUT, Q2. By allowing the capacitor to charge with high gate voltage and periodically lowering gate voltage, when Ql fires, the timing resistor can be a value which supplies a much lower current than....
-
This 2-band compressor splits the audio into high and low frequencies and allows independent adjustmen..
-
To obtain a 1000:1 Sweep Range, the voltage across external resistors Ra and Rb must decrease to nearly zero. This requires that the highest voltage on control pin 8 exceed the voltage at the top of Ra and Rb by a few hundred millivolts. The circuit achieves....
-
In battery-powered applications in which power management is key, a microprocessor may adjust its core voltage corresponding to an increase or a decrease in clock speed, allowing full processing power when necessary but not wasting excess power when idle.....
-
This circuit is for low voltage applications requiring high power outputs. Output power levels of LO W into 4 ohm from 6 V and 3 V into 8 ohm from 12 V are typical. Coupling capacitors are not necessary since the output dc levels will-be within a few tenths....
-
This circuit offers 10- to 15-dB gain from 400 to 850 MHz and is therefore eminently suitable for situations where th..
-
The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 terminals will NOT do. The Alarm is set by pressing a single key. Choose the key you want to use and....
-
A Universal Power supply based on the L200 regulator, which includes an outboard pass transistor to boost output currents up to 4 amps...
-
Opamps are very useful. But one of their major drawbacks is the requirement of a dual supply. This seriously limits their applications in fields where a dual supply is not affordable or not practicable.
This circuit solves the problem to a certain extent.....
-
This project aimed to develop a wireless system to detect and allow only the authorized persons. The system was based on Radio Frequency Identification (RFID) technology and consists of a passive RFID tag. The passive micro transponder tag collects power....
-
This circuit is useful in liquids level or proximity detection. It operates detecting the distance from the target by reflection of an infra-red beam. It can safely detect the level of a liquid in a tank without any contact with the liquid itself. The....
-
Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and cyan (secondary colours); and black and white. The circuit is based on the fundamentals of optics....
-
An op-amp comparator is used to compare the converter output with a dc threshold voltage. The circuit flashes the LED when the input frequency exceeds 100 Hz. Increases in frequency raise the average current out of terminal 3 so that frequencies above 100 Hz....
-
The solar cell is connected across the input of the FET (field-effect transistor), Ql, so that it will produce positive dc voltage to the gate when activated by light shining through the open shutter, decreasing the negative gate-source bias already....
-
Bugdozer is an autonomous mini-Sumo robot. Her main board consists of a MC68HC908GP32 microcontroller along with input/output support chips, a voltage regulator, a crystal oscillator, and the usual assortment of resistors, capacitors, and switches. All chips....
-
Two op amps used in a bridge circuit configuration detect high and low light levels. Potentiometer R2 sets the dark level and Rl controls the light level. R3 is set so that about lA the supply voltage appears across R4 at the desired light level. ..
-
The circuit will operate reliably from below 1 MHz to above 400 MHz. With Vcc = 5 V the output of the second inverter essentially attains a full swing from 0 V to 5 V. Such large logic output levels and broad frequency range capabilities make this oscillator....
-
Normally the active high output from the inverter is used to enable the remainder of the CMOS gates which then perform some useful function. When the SIMD1 triggers at night, it snaps on and the output signal can be used to control the 5 remaining 74HC14....
-
Morse Tutor is a program written in C++. It can be used for learning or sending morse code. Morse code uses long (dash) and short (dot) sounds to communicate. The dot is the basic unit and the dash is equal to the length of three dot's. Morse Code was....
-
The slot machine`s realistic action is provided by seven ICs and three displays, as shown. Two 555 CMOS timer ICs generate pulses. IC1 is used to generate the clock pulses for the entire electronic slot machine. The pulses are coupled from the output (pin....
-
With the amount of equipment in home entertainment centers today the need to be able to vary the gain of the audio or video signal is needed. I found this particular circuit helpful when used in conjunction with the Universal Descrambler and a Stabilizer....
-
Very simple and useful circuit for amplify the stereo signals .The circuit dissipates roughly 28 watts of heat, so a good heatsink is necessary. The chip should run cool enough to touch with the proper heatsink installed .the circuit operates at 12 Volts at....
-
The unit described here is simple to build, and can be quite small. The picture below shows the prototype, in a box 175mm wide, 210mm deep and 55mm high. The single circuit board is 140 x 90mm, so there's plenty of room inside for another board (a local....
-
This wideband RF isolation amplifier has a frequency response of 0.5 to 400 MHz ± 0.5 dB. This two stage amplifier can be used in applications requiring high reverse isolation, such as receiver intermediate-frequency (IF) strips and frequency distribution....
-
The applet shows a simulation of Chua's circuit, plotting the voltage measured across C1 against the voltage measured across C2. This corresponds to the display on an X-Y oscilloscope with probes connected across these capacitors. The initial values of the....
-
Leaving aside the complex chargers, "stuffed" electronics capacitor charger is one of the best connections. Charging current is limited by the resistor (or other element of the changing excess energy into heat), but the reactance of the capacitor to the....
An audio signal applied to VI is passed through the operational amplifier 741, U2. After being amplified, the output signal V2 is sampled and applied to a negative voltage doubler / rectifier circuit composed of diodes CRI and CR2, with the capacitor C1. The....
This circuit provides interferenced rejection for the CW operator. The 567 phase-locked loop is configured to respond to tones from 500 to 1100 Hz. The Schmitt trigger reduces the weighting effect caused by the output of the PLL remaining low after removal....
A high-frequency audio signal (15 to 25 kHz) generated by Ul is fed to buffer Ql and SPKR1. A portion is f..
This thing is a very nifty capacitive sensor. For you europeans, this little gem is used in north america mostly for detecting wooden beams behind drywall or plaster. I`ll take one of these over the new design any day, because these ones don`t error out....
The circuit provides a windshield wiper delay, dynamic braking and windshield wipers when they reach the rest position. This prevents the blades passing, which could lead them to stop at a point where they interfere with the vision of drivers. With the....
The XR-T5995 Speech Network is a monolithic integrated circuit specifically designed for implementing a low cost telephone circuit. ..
This circuit is used for remote photographic flash units that flash at the~ame time as the flash attached to the camera. This circuit is designed to the trigger cord or hot shoe connection of a commercial portable flash unit and triggers the unit from the....
Designing a high-voltage switching power supply that can produce a sustained arc can be challenging. This compact and efficient design delivers 1 kV at 20W and can withstand a continuous arcing, or short-circuit, condition (Figure 1). It uses standard,....
Here is a circuit that implements phase-control of heaters, adjusting their power smoothly from zero to around 95% of the rated power, keeping the room temperature to within 1 or 2 degrees, while using few components. Notice that this is entirely an AC....
A very simple motion transducer can be constructed using the circuit shown. The output is biased to one-half the supply voltage. This requires special interface circuitry for the signal readout. One simple method is to use a zero center meter in a bridge....
Initially the neon and xenon lamps are not conducting and act like a very high (almost infinite) resistance. Capacitors Cl and C4 in conjunction with DI and D2 form a voltage doubler circuit, which can charge C2 up to about 300 Vdc after several ac cycles.....
In this strobe-light, two circuits are needed; one circuit charges a capacitor placing 320 V de between the cathode and anode of the flashtube. The other circuit provides bursts of approximately 4000 V to trigger the flashtube into conduction. The....
A keyed power input connector, series rectifier and a shunt rectifier, both 1N4007, prevent reverse voltage from being applied to the power input. A 27 volt metal oxide varistor clamps the voltage to the 78L05 that follow it, to less than 30 volts, thus....
The low Rds and high peak current capability ofthe DG419 makes it ideal for discharging an·integrator capacitor. A high logic input pulse disconnects the integrator from the analog input and discharges the capacitor. ..
I recently prototyped a Tube Screamer type circuit to refresh my memory about the sound of this pedal. I used a borrowed TS-808 and a Pro Reverb in the mid 80s for several weeks while my modded Twin Reverb was being fixed and I remembered it sounding pretty....
The circuit is quick and easy to put together and install, and tells you when battery voltage falls below the set limit as established by Rl (a 10,000-ohm potentiometer). It can indicate, via LED 1, that the battery may be defective or in need of change if....
Sometimes electrolytic capacitors that are stored for some time will exhibit high leakage currents..
The high-speed peak detector uses a highly accurate, fast s/h amplifier controlled by a highspeed comparator. The s/h amplifier holds the peak voltage, until the comparator switches the amp to its sample mode, to capture a new, higher voltage level. The....
The LT®3465/LT3465A are step-up DC/DC converters designed to drive up to six LEDs in series from a Li-Ion cell. Series connection of the LEDs provides identical LED currents and eliminates the need for ballast resistors. These devices integrate the Schottky....
The device described here does just that. The circuit connects to the doorbell circuit - taking power from the 18 VAC from the doorbell transformer and switching power to the doorbell circuit most of the day. The user interface is a pushbutton, a toggle....
This circuit switches its dc/dc converter, IC1, off whenever the large filter capacitor, C6, has suffic..
The most amazing thing about this project is the small number of parts. My boss joked that it involves 17 cents worth of parts and 1000 dollars worth of programming. But don`t worry -- the code is free to you! That means you can build this TV pong game in a....
The device generates an adjustable frequency of low to medium powered IR pulses of invisible energy and must be treated with care. The portable battery pack is stepped up to 200 to 300 volts by the inverter circuit consisting of Ql, Q2, and Tl. Ql conducts....
This simple 10 watts audio power amplifier is designed for home-brewed purpose. It is based on an Audio Power Amplifier IC that is called TDA2030. It is a monolithic integrated circuit in Pentawatt package, intended for use as a low frequency class AB....
In a lot of cars, the car-radios use amplifiers that their output power does not exceed the 5W with enough distortion in the limits of power. The problem is untied with the utilisation of external amplifiers, that will have the possibility giving much....
This circuit was submitted by Graham Maynard from Newtownabbey, Northern Ireland. It has an exceptionally fast high frequency response, as demonstrated by applying an 100kHz squarewave to the input. All graphs were produced using Tina Pro...
The circuit is basically a NE555 monostable, the only major difference being its method of triggering. The trigger input is biased to a high value by the 22 ohm resistor. When the contact plates are touched, the skin resistance of the operator will lower....
A clever charger circuit that safely can charge any Ni-Cd battery. Offers charge current sellection, polarization detection and protection and the ability to connect many batterys in siries. Ni-Cd bateries can be recharged more than 1000 times before become....
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....
Many times we have found itself in the necessity to use a Zener diode and cannot to know the voltage of operation. Many times we cannot read the characteristics or the type that is written on her. In this case, but in different we can also use the circuit....
An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13,....
This inverter is very easy to construct, reliable, and even powerful enough to light up a 15W florescent tube (if you cool your transistor well). The only hard-to-find piece of this baby is the so-called yellow inverter transformer. It's a miniature high....
This circuit is based around the 555 timer circuit, used as an astable (free running) oscillator. The frequency (pitch) of the tone is set by the resistors and capacitors in the left side of the circuit. The first one is a potentiometer (variable resistor),....
At the heart of the whistle swatch are a pair of tone detectors, each of which is built around an LM567 tone decoder, which are supported by a minimum of additional components. This whistle switch is designed to respond to only two or more occurrences of a....
In these applications, a pulse input at % is differentiated by a C-R network and the negative-going edge at pin 6 causes the input comparator to trigger the timer circuit. Just as with a V-to-F converter, the average current flowing out of pin 1 is IaverAGE....
"Should I cut the blue wire... or the red...?" This is a very common phrase in many movies when the action hero has a bomb in front of him with little time left and he has to choose which wire to cut and stop the bomb from exploding saving millions of....
This page discusses the various ways that a voltage regulator can be made using two transistors. If one of these transistors is the series-pass element, then the other must be the error amplifier, so there is a distinct limit to the number of possible....
Robot Beacon is a rotating light. We have called it Robot Beacon as it has been designed as an addition for a robot, but it can be used for many applications. It can be used as a mast-head beacon on a boat or as an "all-round" warning light on a bike.....
If the piclist is an any indication the 16f877 seems to be the new favorite hobby microcontroller, a position that used to be occupied by the 16f84/16c84. Compared to is older brethren the 16f877 has much more to offer at around twice the price. As for all....
The circuit will modulate the light from the LED using a crystal microphone or a loudspeaker output. To obtain the maximum range, the optical system must be efficient (see example). Either a convex lens or a concave mirror can be used to convert the LED....
This circuit traps a single positive pulse from a square-wave train. Following the rising edge of an input command, the pulse-out signal emits a replica of one positive pulse of the clock signal simultane ous with the clock signal"s next rising edge. The....
When the output is high, R3 and R4 are in parallel, and CI charges via Rl until the current in R2 equals that a..
This digital volume control has no pot to wear out and introduces almost no noise in the circuit. Instead, the volume is controlled by pressing UP and DOWN buttons. This simple circuit would be a great touch to any home audio project. Using a dual polariity....
Temperature control is achieved using the REF-02 +5 V Reference/Thermometer and a CMP-02 Precision Low Input Current Comparator. The CMP-02 turns on a heating element driver (Ql) whenever the present temperature drops below a setpoint temperature determined....
This bug can be attached to anything from a glider to a pot plant and you can track it with a radio. Why track a pot plant? The Beeper is the result of many requests for a mini tracking device and introduces a new world of tracking. The circuit is very....
Fiber Optic applications require analog drivers and receivers operating in the megahertz region. This complete analog transmission system is suitable for optical communication applications up to 3 MHz. The transmitter LED is normally biased at 50 mA....
Ql and Q2 are general purpose transistors. The 10 K input pot is adjusted to a point just short of where Ql turns on as indicated by K pulling in. K is any 5 V reed relay. With the values shown for R (100 K) and C (47 µf), timing values from 5 to slightly....
This circuit has a 100 mV hysteresis which can be used in applications where very fast transition times are required at the output even though the signal is very slow. The hysteresis loop also reduces false triggering due to noise on the input..
This single-chip circuit adjusts its audio gain according to the ambient noise picked up by the microphone. When ..
The second gate (G2) of a MOSFET can be used to incorporate a crystal oscillator into the same stage as a frequency mixer. Although old hat with tubes, this scheme is seldom seen in dual-gate MOSFET circuitry. L3, 03, and XI form the crystal oscillator, and....
this tone generator can be used to control your robot. you will need to use the tone decoder for this. to widen the range, higher or lower - substitute a higher, or lower valued capacitor for c1. for frequencies about 5khz and 15khz, use a piezoelectric....
Input terminal VIN is connected to the +V line of tbe circuit that the indicator is to monitor, and the grounds of botb circuits are connected togetber. The position of potentiometer Rl"s wiper determines Q1"s base voltage. As long as the transistor....
Electronic scales have come into wide use and the HA-510X, as a very low noise device, can improve such designs. This circuit uses a staingauge sensing element as part of a resistive Wienbridge. An auto-zero circuit is also incorporated into this design by....
This circuit can detect smoke and a number of gases (CO, CO2, methane, coal gas and others) with a 10 ppm sensitivity. It uses a heated surface semiconductor sensor. Detection occurs when the gas concentration increase causes a decrease of the sensor element....
Anyone performing their own automobile tune-ups knows how important it is to know your engines speed. With this tachometer, you can measure your engines speed without any connections or annoying timing lights...
A multi wire cable tester with a separate LED for each wire. Will show open circuits, short circuits, reversals, earth faults, continuity and all with four IC`s. Designed initially for my intercom, but can be used with alarm wiring, CAT 5 cables and more...
The project we have chosen as our example is an RS232 to RS485 converter. This is a often needed device which can demonstrate a lot of principles of circuit design, and hopefully the finished project will be useful to some people, just as it stands. Without....
This document tells about one of my experiments with semiconductor laser modules. I bought one semiconductor laser for all kinds of experiments. This TIM202 module is a small (38x14x14 mm) semiconductor laser module, similar to those types used in laser....
Last year, I found a 31 day pendulum wall clock (dissambled) in a box of parts at a swap meet and decided to try and put it together and regulate it with a quartz crystal oscillator. The escapement part that rocks back and forth and drives the pendulum was....
This self-starting fixed-frequency oscillator circuit gives excellent frequency stability. R1 and C 1 comprise the frequency-determining network, while R2 provides the regenerative feedback. Diode D 1 enhances the stability by compensating for the....
The NE564 is used as an FM demodulator. The connections for operation at 5 V and 12 V are shown in Figures 21-4A and 21-4B. The input signal is ac coupled with the output signal being extracted at Pin 14. Loop filtering is provided by the capacitors at Pins....
This circuit is meant to be driven by a 1-MHz standard signal of a few volts amplitude. Ul through U5 are 7490 decade counter/divider and produce a division ratio of 100,000:1. Successive divisions of 10 can be tapped off, if desired, between stages. ..
In this application, the timer is connected in the monostable mode. The circuit is triggered with a continuous pulse train and the threshold voltage is modulated by the signal applied to the control voltage terminal at pin 5. This has the effect of....
The PCB is at the center of any electronic product. Literally, the enclosure surrounds the board, and figuratively, all the mathematics, the science, the software, these all run on the board. That’s why the PCB is at the center of our tools, and our company.....
This circuit converts a tape recorder into a completely automatic telephone conversation recording instrument that needs no external power source. Voltage at the switch terminals of tape recorder applied to a pair of Darlington-connected transistors, Ql and....
As a piece of test equipment, an audio oscillator has to be considered essential for anyone working in with hi-fi gear. Together with an audio millivoltmeter (as described in Project 16), and even better if you have access to an oscilloscope, you will be....
IR radiation from LED2 (modulated by a 1-kHz wave) is keyed by Ul, and Ql is radiated. Reflected IR energy i..
This AC motor speed controller can handle most universal type (brushed) AC motors and other loads up to about 250W. It works in much the same was a light dimmer circuit; by chopping part of the AC waveform off to effectively control voltage. Because of this....
SuiperSpice`s philosophy is centered around the edit schematic, run simulation, view waveforms, probe signals, view waveforms, edit schematic cycle. All key issues have been automated. You can effortlessly modify the schematic, rerun and inspect new....
The circuit lowers the effective peak current of the output PUT, Q2. By allowing the capacitor to charge with high gate voltage and periodically lowering gate voltage, when Ql fires, the timing resistor can be a value which supplies a much lower current than....
This 2-band compressor splits the audio into high and low frequencies and allows independent adjustmen..
To obtain a 1000:1 Sweep Range, the voltage across external resistors Ra and Rb must decrease to nearly zero. This requires that the highest voltage on control pin 8 exceed the voltage at the top of Ra and Rb by a few hundred millivolts. The circuit achieves....
In battery-powered applications in which power management is key, a microprocessor may adjust its core voltage corresponding to an increase or a decrease in clock speed, allowing full processing power when necessary but not wasting excess power when idle.....
This circuit is for low voltage applications requiring high power outputs. Output power levels of LO W into 4 ohm from 6 V and 3 V into 8 ohm from 12 V are typical. Coupling capacitors are not necessary since the output dc levels will-be within a few tenths....
This circuit offers 10- to 15-dB gain from 400 to 850 MHz and is therefore eminently suitable for situations where th..
The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with 7 terminals will NOT do. The Alarm is set by pressing a single key. Choose the key you want to use and....
A Universal Power supply based on the L200 regulator, which includes an outboard pass transistor to boost output currents up to 4 amps...
Opamps are very useful. But one of their major drawbacks is the requirement of a dual supply. This seriously limits their applications in fields where a dual supply is not affordable or not practicable. This circuit solves the problem to a certain extent.....
This project aimed to develop a wireless system to detect and allow only the authorized persons. The system was based on Radio Frequency Identification (RFID) technology and consists of a passive RFID tag. The passive micro transponder tag collects power....
This circuit is useful in liquids level or proximity detection. It operates detecting the distance from the target by reflection of an infra-red beam. It can safely detect the level of a liquid in a tank without any contact with the liquid itself. The....
Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and cyan (secondary colours); and black and white. The circuit is based on the fundamentals of optics....
An op-amp comparator is used to compare the converter output with a dc threshold voltage. The circuit flashes the LED when the input frequency exceeds 100 Hz. Increases in frequency raise the average current out of terminal 3 so that frequencies above 100 Hz....
The solar cell is connected across the input of the FET (field-effect transistor), Ql, so that it will produce positive dc voltage to the gate when activated by light shining through the open shutter, decreasing the negative gate-source bias already....
Bugdozer is an autonomous mini-Sumo robot. Her main board consists of a MC68HC908GP32 microcontroller along with input/output support chips, a voltage regulator, a crystal oscillator, and the usual assortment of resistors, capacitors, and switches. All chips....
Two op amps used in a bridge circuit configuration detect high and low light levels. Potentiometer R2 sets the dark level and Rl controls the light level. R3 is set so that about lA the supply voltage appears across R4 at the desired light level. ..
The circuit will operate reliably from below 1 MHz to above 400 MHz. With Vcc = 5 V the output of the second inverter essentially attains a full swing from 0 V to 5 V. Such large logic output levels and broad frequency range capabilities make this oscillator....
Normally the active high output from the inverter is used to enable the remainder of the CMOS gates which then perform some useful function. When the SIMD1 triggers at night, it snaps on and the output signal can be used to control the 5 remaining 74HC14....
The slot machine`s realistic action is provided by seven ICs and three displays, as shown. Two 555 CMOS timer ICs generate pulses. IC1 is used to generate the clock pulses for the entire electronic slot machine. The pulses are coupled from the output (pin....
With the amount of equipment in home entertainment centers today the need to be able to vary the gain of the audio or video signal is needed. I found this particular circuit helpful when used in conjunction with the Universal Descrambler and a Stabilizer....
Very simple and useful circuit for amplify the stereo signals .The circuit dissipates roughly 28 watts of heat, so a good heatsink is necessary. The chip should run cool enough to touch with the proper heatsink installed .the circuit operates at 12 Volts at....
The unit described here is simple to build, and can be quite small. The picture below shows the prototype, in a box 175mm wide, 210mm deep and 55mm high. The single circuit board is 140 x 90mm, so there's plenty of room inside for another board (a local....
This wideband RF isolation amplifier has a frequency response of 0.5 to 400 MHz ± 0.5 dB. This two stage amplifier can be used in applications requiring high reverse isolation, such as receiver intermediate-frequency (IF) strips and frequency distribution....
The applet shows a simulation of Chua's circuit, plotting the voltage measured across C1 against the voltage measured across C2. This corresponds to the display on an X-Y oscilloscope with probes connected across these capacitors. The initial values of the....
Leaving aside the complex chargers, "stuffed" electronics capacitor charger is one of the best connections. Charging current is limited by the resistor (or other element of the changing excess energy into heat), but the reactance of the capacitor to the....
