New Circuits Page 206
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As before, there are two sections: the transmitter board and the receiver board, both powered by a separate 9V battery or a fixed voltage power supply, depending on your needs. The transmitter board has an electret microphone module at one end, and the laser....
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Variable resistor R1 adjusts the light threshold at which the circuit triggers. R1`s value is chosen to match the photocells resistance at darkness. The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit.....
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When zero voltage switching is not required, methods of providing this function are illustrated. The lowest parts count version of a solid-state relay is an optoisolator, the triac driver HlU. Unfortunately, the ability of the Hll} to drive a load on a....
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The circuit in Figure 1 can drive high-resistance, low-capacitance piezoelectric loads at a 3-dB bandwidth of 6 kHz. It offers a low-cost alternative to commercial drivers...
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The CDI ignition circuit produces a spark from an ignition coil by discharging a capacitor across the primary of the coil. A 2uF capacitor is charged to about 340 volts and the discharge is controlled by an SCR. A Schmitt trigger oscillator (74C14) and....
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The project described here is one that you can just build and have working straight away (although it is entirely possible that you will want to experiment a bit), and requires only a small handful of parts. In its simplest form, there are no active....
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The transistors form a differential pair with an active current-source tail. This configuration, known technically as a variable-transconductance multiplier, has an output proportional to the product of the two input signals. Multiplication occurs due to the....
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The electromagnetic ring launcher is comprised of.four subcircuits: a clock circuit (built around U5, a 555 oscillator/timer configured for astable operation), a count-down/display circuit (built around U3), a 74190 synchronous up/down counter with BCD....
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The circuit consists of the launch timer itself and an automatic-off timer. When power is applied to that IC, the countdown LED's sequence is on until they are all lit. When the last one LED1, is fully lit, transistor Ql saturates, energizing RY2. When that....
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A generalized circuit diagram of the two-pole state-variable active filter is shown. The state-variable filter can be inverting or noninverting and can simultaneously provide three outputs: low-pass, bandpass, and high-pass. A notch filter can be realized....
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This circuit offers the best of both worlds. It can be combined with a low input offset voltage and drift without degrading the overall system`s dynamic performance. Compared to a standalone FET input operational amplifier, the composite amplifier circuit....
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This figure shows a one-of-two switch with a sunnning amplifier. The video source"s line can be terminated either externally or internally to switch RO. With this termination resistor, a load change of less than 1 0 will be seen by the source when the....
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This circuit monitors car battery voltage. It provides an indication of nominal supply voltage as well as low or high voltage. RV1 and RV2 adjust the point at which the red/yellow and yellow/green LEDs are on or off. For example the red LED comes on at 11V,....
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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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his circuit is just an implementation of the 7805 integrated voltage regulator. What this little component does is to lower a voltage and stabilize it by reducing noise and ripple, in order for circuits to have the constant voltage needed to work correctly...
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This nonisolated, unregulated, minimum component converter fills the void between low-power zener regulation and the higher power use of a 60-Hz input transformer. It is intended for use where)"er a nonisolated supply can be used safely. The circuit....
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On board the AVRs that can be programmed are those in the schematic. For other members of AVR family or the rest programmable ICs that Ponyprog can program, there is the J1 connector (CON10) which allows expanding the programmer's hardware. See Ponyprog's....
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The relay which applies power to the wiper motor is actuated at periodic intervals by the timer circuit, closing the wiper motor contacts. Potentiometer R1 serves as the pulse rate control and potentiometer R5 as the pulse width control. ..
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The circuit uses approximately 150 µA of current, allowing the circuit to steal its power from the bus via the Schottky diode, D1. Because the circuit is sensing water that is part of the electrical circuit, you should use an ac-coupled signal to avoid....
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The circuit keeps the courtesy light on for 30 seconds after you close the door. The lead from the door switch is removed and connected to the 555 circuit. The 555 is arranged in a monostable mode, and is triggered by the door switches. The output drives....
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This crystal oscillator is designed to operate with fundamental crystals with less than 1 mW dissipated in the crystal. The signal current is filtered by the crystal and develops a voltage across a capacitor with about 500 ohm of reactance. The resulting....
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This circuit gives a 3 phase square-wave output for a variable speed motor drive. Operation is straightforward, the 4017 counter is synchronously reset after six clock inputs. The she outputs are combined to give the required waveforms. It is interesting to....
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Like its predecessor, AN67, this Application
Note includes circuits for high speed video, interface
and hot swap circuits, active RC and switched capacitor
filter circuitry and a variety of data conversion and
instrumentation circuits...
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The control of both direction and of proportional motor speed is achieved by rotation of a single potentiometer. The motor driver is an SGS integrated circuit L293 which will drive up to 1 amp in either direction, depending on the logic state of input 1 and....
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This circuit is intended as a revolution control for small dc motors as fitted, for instance, in small electric drills (..
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The circuit in Figure 1 is an effective driver for LCDs. The circuit comprises two main sectionsthe ICM7211 drivers (IC2 and IC3) and the YN06 display itself (IC1). The Intersil (www.intersil.com) ICM7211 is a 4-bit LCD driver that needs no external....
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EZRoute2000, from Bill Jenkins, is the completely re-written 32-bit version of EZRoute Pro, for all Windows platforms. Includes schematic capture, interactive symbol editor, libraries, pc board editor, 1000 shape pad table, gerber output and viewer. Free....
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This variable-frequency, audio bandpass filter is built around two 741 op amps that are connected in cascade. Two 741 op amps are configured as identical RC active filters and are connected in cascade for better selectivity. The filter`s tuning range is....
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This circuit is a RF modulator which can be used for modulating of video signals. The P1 controls the Light and the P2 controls the contrast of video signal. The RF modulated output signal can be received on the VHF band ( about 189 MHz ). Note that the....
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This simple and inexpensive circuit built around a popular CMOS hex inverter IC CD4069UB offers four sequential switching outputs that may be used to control 200 LEDs (50 LEDs per channel), driven directly from mains supply. Input supply of 230V AC is....
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You will need to go to extremes with the heatsink (fan cooling is highly recommended). It was originally intended for "light" intermittent duty, suitable for an equalised subwoofer system (for example using the ELF principle - see the Project Page for the....
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The schematic shown, is a 2 transistor signal amplifier between 10 MHz to 30 MHz. The BF256C and the BF494 are very popular transistors and are easy to find. The transformer works as insulator and amplifier.
http://www.next.gr/rf/antennas/active-antennas/..
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In recent years, following CD`s introduction, vinyl recordings are almost disappeared. Nevertheless, a phono preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap....
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This circuit will charge a 12v battery (10 NiMH cells) @ approx 220mA.
It is a very simple circuit but requires correct setting up.
The circuit is designed around a 12vDC, 500mA plug pack. This type of plug pack delivers about 17.5v to 18.5v DC on....
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The power supply, with electronic stabilisation - mainly those of laboratories - it should they are protected from ??over current?? that emanates from short-circuits, erroneous association or damage of repaired appliance. The circuit offers effective....
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The MC1596/MC1496 makes an excellent SSB product detector. This product detector has a sensitivity of 3 microvolts and a dynamic range of 90 dB when operating at an intermediate frequency of S MHz. The detector is broadband for the entire high frequency....
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The phone company provides 3 levels of power. With no devices 'off hook' the line rests at 48 volts DC. If you draw any more than a fraction of a milliamp or so, you get the phone company's attention and a dial tone. When the line rings, you get about 100....
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This is basically a flasher circuit modified to turn on and off a bulb instead of a LED. It uses a 555 timer IC working as an astable multivibrator. The flashing rate can be varied from very fast to a maximum of once in 1.5 sec by varying the preset VR1...
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After the recent demise of our multifunction signal generator, we decided to make one of our own. The circuit uses a PIC16F870 (about $3), an R/2R resistor ladder network (for a real fast and cheap D/A), and a few other parts. You can check out the....
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At the heart of the cable tester are two op amps, which are used as a window- comparator to indicate a short- or open-circuit condition. A third op-amp comparator is used to indicate a good circuit (i.e., neither open nor shorted). Colored LEDs are used to....
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This programmer was designed in view of to be flexible, economical and easy to built, the programmer hardware utilizes the standard TTL series parts and no special components are used. The programmer is interfaced with the PC parallel port and there is no....
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The Electronic Dazer is a modern, portable, personal-protection appliance. It generates hight potential energy to ward off vicious animals or other attackers. It is an aid to help exape from a potentially dangerous situation. the device develops about 2,000....
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A unified thermometric controller that can be programmed with simple scripts, integrating the "classic" thermometer/controller pair. You can build a variety of simple machines with the same hardware and a different script : a charting thermometer, a vending....
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The 555 timer IC is connected for Astable Operation, the clock pulses are fed to the 4017 IC via the 10K resistor. The 4017 is a 10 stage counter, each of the outputs is connected to the appropriate LED, as some LEDs need to be on for more than one count, we....
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This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can....
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A PAL color encoder and video summer which requires just composite sync and composite blanking inputs, and a 6-bit binary coded input giving the color information. The inputs are organized as 2 bits per primary color with gamma correction automatically....
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This circuit uses two comparator pairs from an LM339N quad comparator; one pair drives the yellow positive (+)and negative (-)indicators, the other jointly drives the red warn LED3. The circuit draws its power from the unregulated portion of the power....
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The circuit provides illumination when darkness comes. By using the gain available in darlington transistors, this circuit is simplified to use just a photodarlington sensor, a darlington amplifier, and three resistors. ..
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In the early `80s, I read some articles on LED arrays. They described using arrays of 64 or more LEDs as crude oscilloscopes and other interesting things. I decided I`d make one myself - a really big array, 256 LEDs arranged as 16 columns by 16 rows. In....
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It is always desirable to use a low-battery indicator that consumes as little power as possible. For a 9V, 450-mAhr alkaline battery, a 50-µA low-battery indicator can by itself run the battery down in a little more than a year. Battery-powered devices that....
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This circuit is a traditional summing amplifier configuration with the addition of the de clamping circuit. The operation is quite simple; each component-synchronization, color burst, picture information, etc.of the composite video signal is applied to its....
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Circuits that latch one-of-N switches usually use a digital approach. Such circuits are often useful in human-interface situations, such as audio-mixing consoles, video-feed selection, or current-loop-control redundancy systems. In high-precision analog....
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The input signal is applied through R3 to the inverting input of the summing amplifier and the output is taken from the first integrator. The summing amplifier will maintain equal voltage at the inverting and non-inverting inputs. Defining 1/R1C1 as 1 and....
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This circuit changes the average value of the dc supply voltage because of the high switching frequency. The tungsten lamp will have an almost continuous adjustable light output between 0 and 100%..
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C1 = 3 750 pF 500 V silver-mica capacitor. C2= 100 pF preset capacitor (Jackson C803). C3 = 75 pF variable capacit..
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Sometimes called the JFET µ-amp, this circuit provides a very low power, high gain amplifying function. Since µ of a JFET increases as drain current decreases, the lower drain current is, the more gain you get..
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The regen is basically an oscillator circuit with a gain control that allows the user to adjust the feedback to a point just below oscillation or, quite often, just above the critical level such that a small oscillation is present. The typical regen uses a....
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The limitation of car supply voltage (12V) forces to convert the voltages to higher in order to power audio amplifiers. This supply is intended for two channels with 50W max each (of course it depends on the amplifier used). Though it can be easily scaled up....
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Lamp LI will glow brightly and the LED will be out when the battery is low and being charged, but the LED will be bright and the light bulb dim when the battery is almost ready. Ll should be a light bulb rated for the current you want (usually the battery....
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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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Many times we needed a variety of voltages, from a battery 12V. With the circuit, we can take voltages smaller or bigger, positive or negative, from a battery 12V. The idea is based in oscillator roughly 7KHZ, round the R1, C28, that lead the remainder gates....
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The 2N5457 JFET and PN2222 bipolar have inherently high output impedance. Using Rl as a current sensing resistor to provide feedback to the LM101 op amp provides a large amount of loop gain for negative feedback to enhance the true current sink nature of....
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This ten-step adjustable analog level detector is capable Of sinking up to 40 milliam-peres at each output. The voltage range at the input pin should range from 0 to 2 volts. Circuits of this type are useful as liquid-level indicators, pressure indicators,....
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This circuit symmetrically divides an input by virtually any odd number. The circuit contains n + 1h clocks tw..
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Although many circuits use the varying-capacitance method for checking liquid levels, this simple resistive circuit is much easier to construct. Even a tank of a liquid, such as water, has sufficient conductive salts in solution for this method to work.....
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This device is a simple timer, allowing to keep on the headlights of your vehicle for about 1min. and 30sec., e.g. when accessing some dark place, without the necessity of coming back to switch-off the lights...
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The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a....
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In this circuit, an LM741 op amp drives a Wien-bridge network using two zener diodes as..
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The vacuum tube is still alive and useful in some applications, as in this CW transmitter, The circuit was built in old-fashioned breadboard style on a wooden base. Old table radios are a good source of parts for this circuit. V3 is used as a ballast....
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A device designed for measuring time and temperature used in chemistry laboratory. The circuit employs a 89C4051, 20-pin CMOS Microcontroller with built-in 4kB code memory. Temperature was measured by LM35D, National Semiconductor Temperature sensor....
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The DVM-to-temperature adapter is built around a single IC, National"s LMlO. That micropower IC contains a stable 0.2 V reference, a reference amplifier and a general-purpose op amp. The circuit is designed for a linear temperature range of 0 to 100°C (32....
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This circuit uses a timer to generate pulses at a 5-ms clock rate. The pulses are shifted into the shift register, one at a ..
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This limiter improves signal-to-noise ratio. It is connected between the detector output and the audio input (if high impedance) or at some relatively high-impedance section between two audio stages—preferably the low level stages.D1 and D2 can be any....
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HA-5190 is rated for ±5 V output swing, and saturates at ±7 V. As with most op amps, recovery from output saturation is slow compared to the amplifier"s normal response time. Some form of limiting, either of the input signal or in the feedback path,....
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The circuit in Figure 1 uses the
MIC2545A-2 and the MIC2778. The MIC2545A-2 is a programmable
current limit high-side switch that is capable of
having current-limit up to 2.5A...
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If you're not familiar with the Arduino, it is "an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software". It has a small microcontroller, a USB port to connect to your computer for programming, a power socket for....
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A opamp. medium power, here its used as amplifier of headphones with possibility drive low loads. It contains in a nutshell two amplifiers. The voltage gain, has been determined in 40dB, from the R3-4 and R11-12, for each channel, respectively. The....
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Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need. Output power: well in excess of 25Watt RMS @ 8 Ohm (1KHz sinewave)....
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Another one unit of graphic EQ. five bands. The basic difference with the other circuits is, that I use instead of IC, transistor and the power supply, go up in +/- 24V DC, ensuring low distortion and bigger margins of overloading. With switch S1, we can....
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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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The circuit behaves like a zener diode over a large range of voltages. The current passing through the voltage divider R1-R2 is substantially larger than the transistor base current and is in the region of 8 mA. The stabilizing voltage is adjustable over the....
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This two-chip receiver with minimum external component count has been designed for low-cost fiber optic applications to 100-M baud (50 MHz). The receiver is divided into pre-and postamplifier !Cs for increased stability. The preamplifier IC features low....
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The output of the amplifier is to be measured on a digital voltmeter. Besides being able to accept 20 na to 200 micro amps and output voltages that range form 100 mv to 2 or 3 volts, the amplifier needed to have a low input resistance so the diode could be....
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Apply a signal to each differential amplifier input pair. When the gate voltage is changed from one extreme to the ot..
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This converter allows reception of six metre signals on a two metre receiver. It should therefore be useful for those with single or dual band sets that do not cover 50 MHz...
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Described timer to participate in the current circuit switch - bulb without any modification of existing pipelines.
Connect the timer is in Figure 1 The time switch has only two outlets, which is connected in parallel to the button (Fig. 1a) or switch (Fig.....
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The IR diode"s flash rate is determined by the value of CI, a 220-Â¥ capacitor that sets the rate of oscillation at 1 ..
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This is one of my stroboscope designs. Usually many stoboscope circuit work directly from mains voltage, but this circuit uses 12V DC intead od mains AC. This is very good idea if you don't want to mess with direct mains voltage connected circuit or you want....
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This circuit is useful in amateur radio VHF and UHF work where a mast-mounted antenna preamp is used for receiving. The kit controls T-R switching and change-over relay sequencing so that high RF levels are prevented ..
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This multivibrator uses a CA3420 BiMOS op amp to provide improved frequency stability. The output frequency remains essentially independent of supply voltage. Because of the inherent buffering action of pin 6, ..
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Using only one IC and six passive components, this pulse generator has a frequency range of 400 to 4000 Hz and an adjustable duty cycle of 1 to 99%. A threshold detector (ICA) and an integrator (ICB) generate a triangular waveform. A positive voltage at the....
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This is an simple Vox AC amplifier. The circuit is not very clear but is readable...
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The input stage is comprised of a both halves of a 6SL7 octal dual hi-mu triode in a differential amp configuration with a 1ma constant current cathode load. I'm using field-effect (constant-current) diodes for simplicity. the diff amp approach was chosen....
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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 programmer requires only a basic terminal program capable of uploading an ascii PIC HEX file. It does not matter what operating system or computer (MAC, Win98, XP, Vista, DOS, Linux, etc.) is used to talk to it. All of the software necessary for....
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This is a portable oscilloscope adapter that it can be held in breast pocket. Its operation is only sampling and sending to host PC. The most of functions of the oscilloscope are processed by host PC. Therefore, oscilloscope adapter can be simplified. This....
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The device serves to quickly establish the status of an indicative power cells. I built it for his children, so they can determine the degree of self-discharge batteries in a variety of toys. WAS tester designed to test the fast primary (zinc, alcaline)....
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If we have a lot of parallel telephones on a telephone line, we needed a unit that will have the possibility of showing if somebody of the telephone has raised the earphone. Our this possibility give the circuit. The circuit is connected at parallel with the....
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The circuit can be tuned to respond to signals between 50 MHz and 500 GHz. The economy model is shown in Fig. 1, and the deluxe model is shown in Fig. 2.The first op amp in each circuit functions as a current-to-voltage converter. In the economy model IClb....
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Provides remote control for ac-powered devices by using the beam of a flashlight as a magic wand. The important aspect of this gadget is that it remembers. Activate it once to apply power to a device and it stays on. Activate it a second time and power goes....
As before, there are two sections: the transmitter board and the receiver board, both powered by a separate 9V battery or a fixed voltage power supply, depending on your needs. The transmitter board has an electret microphone module at one end, and the laser....
Variable resistor R1 adjusts the light threshold at which the circuit triggers. R1`s value is chosen to match the photocells resistance at darkness. The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit.....
When zero voltage switching is not required, methods of providing this function are illustrated. The lowest parts count version of a solid-state relay is an optoisolator, the triac driver HlU. Unfortunately, the ability of the Hll} to drive a load on a....
The circuit in Figure 1 can drive high-resistance, low-capacitance piezoelectric loads at a 3-dB bandwidth of 6 kHz. It offers a low-cost alternative to commercial drivers...
The CDI ignition circuit produces a spark from an ignition coil by discharging a capacitor across the primary of the coil. A 2uF capacitor is charged to about 340 volts and the discharge is controlled by an SCR. A Schmitt trigger oscillator (74C14) and....
The project described here is one that you can just build and have working straight away (although it is entirely possible that you will want to experiment a bit), and requires only a small handful of parts. In its simplest form, there are no active....
The transistors form a differential pair with an active current-source tail. This configuration, known technically as a variable-transconductance multiplier, has an output proportional to the product of the two input signals. Multiplication occurs due to the....
The electromagnetic ring launcher is comprised of.four subcircuits: a clock circuit (built around U5, a 555 oscillator/timer configured for astable operation), a count-down/display circuit (built around U3), a 74190 synchronous up/down counter with BCD....
The circuit consists of the launch timer itself and an automatic-off timer. When power is applied to that IC, the countdown LED's sequence is on until they are all lit. When the last one LED1, is fully lit, transistor Ql saturates, energizing RY2. When that....
A generalized circuit diagram of the two-pole state-variable active filter is shown. The state-variable filter can be inverting or noninverting and can simultaneously provide three outputs: low-pass, bandpass, and high-pass. A notch filter can be realized....
This circuit offers the best of both worlds. It can be combined with a low input offset voltage and drift without degrading the overall system`s dynamic performance. Compared to a standalone FET input operational amplifier, the composite amplifier circuit....
This figure shows a one-of-two switch with a sunnning amplifier. The video source"s line can be terminated either externally or internally to switch RO. With this termination resistor, a load change of less than 1 0 will be seen by the source when the....
This circuit monitors car battery voltage. It provides an indication of nominal supply voltage as well as low or high voltage. RV1 and RV2 adjust the point at which the red/yellow and yellow/green LEDs are on or off. For example the red LED comes on at 11V,....
A Universal Power supply based on the L200 regulator, which includes an outboard pass transistor to boost output currents up to 4 amps...
his circuit is just an implementation of the 7805 integrated voltage regulator. What this little component does is to lower a voltage and stabilize it by reducing noise and ripple, in order for circuits to have the constant voltage needed to work correctly...
This nonisolated, unregulated, minimum component converter fills the void between low-power zener regulation and the higher power use of a 60-Hz input transformer. It is intended for use where)"er a nonisolated supply can be used safely. The circuit....
On board the AVRs that can be programmed are those in the schematic. For other members of AVR family or the rest programmable ICs that Ponyprog can program, there is the J1 connector (CON10) which allows expanding the programmer's hardware. See Ponyprog's....
The relay which applies power to the wiper motor is actuated at periodic intervals by the timer circuit, closing the wiper motor contacts. Potentiometer R1 serves as the pulse rate control and potentiometer R5 as the pulse width control. ..
The circuit keeps the courtesy light on for 30 seconds after you close the door. The lead from the door switch is removed and connected to the 555 circuit. The 555 is arranged in a monostable mode, and is triggered by the door switches. The output drives....
This crystal oscillator is designed to operate with fundamental crystals with less than 1 mW dissipated in the crystal. The signal current is filtered by the crystal and develops a voltage across a capacitor with about 500 ohm of reactance. The resulting....
This circuit gives a 3 phase square-wave output for a variable speed motor drive. Operation is straightforward, the 4017 counter is synchronously reset after six clock inputs. The she outputs are combined to give the required waveforms. It is interesting to....
The control of both direction and of proportional motor speed is achieved by rotation of a single potentiometer. The motor driver is an SGS integrated circuit L293 which will drive up to 1 amp in either direction, depending on the logic state of input 1 and....
This circuit is intended as a revolution control for small dc motors as fitted, for instance, in small electric drills (..
EZRoute2000, from Bill Jenkins, is the completely re-written 32-bit version of EZRoute Pro, for all Windows platforms. Includes schematic capture, interactive symbol editor, libraries, pc board editor, 1000 shape pad table, gerber output and viewer. Free....
This variable-frequency, audio bandpass filter is built around two 741 op amps that are connected in cascade. Two 741 op amps are configured as identical RC active filters and are connected in cascade for better selectivity. The filter`s tuning range is....
This circuit is a RF modulator which can be used for modulating of video signals. The P1 controls the Light and the P2 controls the contrast of video signal. The RF modulated output signal can be received on the VHF band ( about 189 MHz ). Note that the....
This simple and inexpensive circuit built around a popular CMOS hex inverter IC CD4069UB offers four sequential switching outputs that may be used to control 200 LEDs (50 LEDs per channel), driven directly from mains supply. Input supply of 230V AC is....
You will need to go to extremes with the heatsink (fan cooling is highly recommended). It was originally intended for "light" intermittent duty, suitable for an equalised subwoofer system (for example using the ELF principle - see the Project Page for the....
The schematic shown, is a 2 transistor signal amplifier between 10 MHz to 30 MHz. The BF256C and the BF494 are very popular transistors and are easy to find. The transformer works as insulator and amplifier. http://www.next.gr/rf/antennas/active-antennas/..
In recent years, following CD`s introduction, vinyl recordings are almost disappeared. Nevertheless, a phono preamplifier is still useful for listening old vinyl discs from a well preserved collection. This simple but efficient circuit devised for cheap....
This circuit will charge a 12v battery (10 NiMH cells) @ approx 220mA. It is a very simple circuit but requires correct setting up. The circuit is designed around a 12vDC, 500mA plug pack. This type of plug pack delivers about 17.5v to 18.5v DC on....
The power supply, with electronic stabilisation - mainly those of laboratories - it should they are protected from ??over current?? that emanates from short-circuits, erroneous association or damage of repaired appliance. The circuit offers effective....
The MC1596/MC1496 makes an excellent SSB product detector. This product detector has a sensitivity of 3 microvolts and a dynamic range of 90 dB when operating at an intermediate frequency of S MHz. The detector is broadband for the entire high frequency....
The phone company provides 3 levels of power. With no devices 'off hook' the line rests at 48 volts DC. If you draw any more than a fraction of a milliamp or so, you get the phone company's attention and a dial tone. When the line rings, you get about 100....
This is basically a flasher circuit modified to turn on and off a bulb instead of a LED. It uses a 555 timer IC working as an astable multivibrator. The flashing rate can be varied from very fast to a maximum of once in 1.5 sec by varying the preset VR1...
After the recent demise of our multifunction signal generator, we decided to make one of our own. The circuit uses a PIC16F870 (about $3), an R/2R resistor ladder network (for a real fast and cheap D/A), and a few other parts. You can check out the....
At the heart of the cable tester are two op amps, which are used as a window- comparator to indicate a short- or open-circuit condition. A third op-amp comparator is used to indicate a good circuit (i.e., neither open nor shorted). Colored LEDs are used to....
This programmer was designed in view of to be flexible, economical and easy to built, the programmer hardware utilizes the standard TTL series parts and no special components are used. The programmer is interfaced with the PC parallel port and there is no....
The Electronic Dazer is a modern, portable, personal-protection appliance. It generates hight potential energy to ward off vicious animals or other attackers. It is an aid to help exape from a potentially dangerous situation. the device develops about 2,000....
A unified thermometric controller that can be programmed with simple scripts, integrating the "classic" thermometer/controller pair. You can build a variety of simple machines with the same hardware and a different script : a charting thermometer, a vending....
The 555 timer IC is connected for Astable Operation, the clock pulses are fed to the 4017 IC via the 10K resistor. The 4017 is a 10 stage counter, each of the outputs is connected to the appropriate LED, as some LEDs need to be on for more than one count, we....
This circuit features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can....
A PAL color encoder and video summer which requires just composite sync and composite blanking inputs, and a 6-bit binary coded input giving the color information. The inputs are organized as 2 bits per primary color with gamma correction automatically....
This circuit uses two comparator pairs from an LM339N quad comparator; one pair drives the yellow positive (+)and negative (-)indicators, the other jointly drives the red warn LED3. The circuit draws its power from the unregulated portion of the power....
The circuit provides illumination when darkness comes. By using the gain available in darlington transistors, this circuit is simplified to use just a photodarlington sensor, a darlington amplifier, and three resistors. ..
In the early `80s, I read some articles on LED arrays. They described using arrays of 64 or more LEDs as crude oscilloscopes and other interesting things. I decided I`d make one myself - a really big array, 256 LEDs arranged as 16 columns by 16 rows. In....
This circuit is a traditional summing amplifier configuration with the addition of the de clamping circuit. The operation is quite simple; each component-synchronization, color burst, picture information, etc.of the composite video signal is applied to its....
The input signal is applied through R3 to the inverting input of the summing amplifier and the output is taken from the first integrator. The summing amplifier will maintain equal voltage at the inverting and non-inverting inputs. Defining 1/R1C1 as 1 and....
This circuit changes the average value of the dc supply voltage because of the high switching frequency. The tungsten lamp will have an almost continuous adjustable light output between 0 and 100%..
C1 = 3 750 pF 500 V silver-mica capacitor. C2= 100 pF preset capacitor (Jackson C803). C3 = 75 pF variable capacit..
Sometimes called the JFET µ-amp, this circuit provides a very low power, high gain amplifying function. Since µ of a JFET increases as drain current decreases, the lower drain current is, the more gain you get..
The regen is basically an oscillator circuit with a gain control that allows the user to adjust the feedback to a point just below oscillation or, quite often, just above the critical level such that a small oscillation is present. The typical regen uses a....
The limitation of car supply voltage (12V) forces to convert the voltages to higher in order to power audio amplifiers. This supply is intended for two channels with 50W max each (of course it depends on the amplifier used). Though it can be easily scaled up....
Lamp LI will glow brightly and the LED will be out when the battery is low and being charged, but the LED will be bright and the light bulb dim when the battery is almost ready. Ll should be a light bulb rated for the current you want (usually the battery....
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....
Many times we needed a variety of voltages, from a battery 12V. With the circuit, we can take voltages smaller or bigger, positive or negative, from a battery 12V. The idea is based in oscillator roughly 7KHZ, round the R1, C28, that lead the remainder gates....
The 2N5457 JFET and PN2222 bipolar have inherently high output impedance. Using Rl as a current sensing resistor to provide feedback to the LM101 op amp provides a large amount of loop gain for negative feedback to enhance the true current sink nature of....
This ten-step adjustable analog level detector is capable Of sinking up to 40 milliam-peres at each output. The voltage range at the input pin should range from 0 to 2 volts. Circuits of this type are useful as liquid-level indicators, pressure indicators,....
This circuit symmetrically divides an input by virtually any odd number. The circuit contains n + 1h clocks tw..
Although many circuits use the varying-capacitance method for checking liquid levels, this simple resistive circuit is much easier to construct. Even a tank of a liquid, such as water, has sufficient conductive salts in solution for this method to work.....
This device is a simple timer, allowing to keep on the headlights of your vehicle for about 1min. and 30sec., e.g. when accessing some dark place, without the necessity of coming back to switch-off the lights...
The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a....
In this circuit, an LM741 op amp drives a Wien-bridge network using two zener diodes as..
The vacuum tube is still alive and useful in some applications, as in this CW transmitter, The circuit was built in old-fashioned breadboard style on a wooden base. Old table radios are a good source of parts for this circuit. V3 is used as a ballast....
A device designed for measuring time and temperature used in chemistry laboratory. The circuit employs a 89C4051, 20-pin CMOS Microcontroller with built-in 4kB code memory. Temperature was measured by LM35D, National Semiconductor Temperature sensor....
The DVM-to-temperature adapter is built around a single IC, National"s LMlO. That micropower IC contains a stable 0.2 V reference, a reference amplifier and a general-purpose op amp. The circuit is designed for a linear temperature range of 0 to 100°C (32....
This circuit uses a timer to generate pulses at a 5-ms clock rate. The pulses are shifted into the shift register, one at a ..
This limiter improves signal-to-noise ratio. It is connected between the detector output and the audio input (if high impedance) or at some relatively high-impedance section between two audio stages—preferably the low level stages.D1 and D2 can be any....
HA-5190 is rated for ±5 V output swing, and saturates at ±7 V. As with most op amps, recovery from output saturation is slow compared to the amplifier"s normal response time. Some form of limiting, either of the input signal or in the feedback path,....
If you're not familiar with the Arduino, it is "an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software". It has a small microcontroller, a USB port to connect to your computer for programming, a power socket for....
A opamp. medium power, here its used as amplifier of headphones with possibility drive low loads. It contains in a nutshell two amplifiers. The voltage gain, has been determined in 40dB, from the R3-4 and R11-12, for each channel, respectively. The....
Can be directly connected to CD players, tuners and tape recorders. Simply add a 10K Log potentiometer (dual gang for stereo) and a switch to cope with the various sources you need. Output power: well in excess of 25Watt RMS @ 8 Ohm (1KHz sinewave)....
Another one unit of graphic EQ. five bands. The basic difference with the other circuits is, that I use instead of IC, transistor and the power supply, go up in +/- 24V DC, ensuring low distortion and bigger margins of overloading. With switch S1, we can....
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....
The circuit behaves like a zener diode over a large range of voltages. The current passing through the voltage divider R1-R2 is substantially larger than the transistor base current and is in the region of 8 mA. The stabilizing voltage is adjustable over the....
This two-chip receiver with minimum external component count has been designed for low-cost fiber optic applications to 100-M baud (50 MHz). The receiver is divided into pre-and postamplifier !Cs for increased stability. The preamplifier IC features low....
The output of the amplifier is to be measured on a digital voltmeter. Besides being able to accept 20 na to 200 micro amps and output voltages that range form 100 mv to 2 or 3 volts, the amplifier needed to have a low input resistance so the diode could be....
Apply a signal to each differential amplifier input pair. When the gate voltage is changed from one extreme to the ot..
This converter allows reception of six metre signals on a two metre receiver. It should therefore be useful for those with single or dual band sets that do not cover 50 MHz...
Described timer to participate in the current circuit switch - bulb without any modification of existing pipelines. Connect the timer is in Figure 1 The time switch has only two outlets, which is connected in parallel to the button (Fig. 1a) or switch (Fig.....
The IR diode"s flash rate is determined by the value of CI, a 220-Â¥ capacitor that sets the rate of oscillation at 1 ..
This is one of my stroboscope designs. Usually many stoboscope circuit work directly from mains voltage, but this circuit uses 12V DC intead od mains AC. This is very good idea if you don't want to mess with direct mains voltage connected circuit or you want....
This circuit is useful in amateur radio VHF and UHF work where a mast-mounted antenna preamp is used for receiving. The kit controls T-R switching and change-over relay sequencing so that high RF levels are prevented ..
This multivibrator uses a CA3420 BiMOS op amp to provide improved frequency stability. The output frequency remains essentially independent of supply voltage. Because of the inherent buffering action of pin 6, ..
Using only one IC and six passive components, this pulse generator has a frequency range of 400 to 4000 Hz and an adjustable duty cycle of 1 to 99%. A threshold detector (ICA) and an integrator (ICB) generate a triangular waveform. A positive voltage at the....
This is an simple Vox AC amplifier. The circuit is not very clear but is readable...
The input stage is comprised of a both halves of a 6SL7 octal dual hi-mu triode in a differential amp configuration with a 1ma constant current cathode load. I'm using field-effect (constant-current) diodes for simplicity. the diff amp approach was chosen....
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 programmer requires only a basic terminal program capable of uploading an ascii PIC HEX file. It does not matter what operating system or computer (MAC, Win98, XP, Vista, DOS, Linux, etc.) is used to talk to it. All of the software necessary for....
This is a portable oscilloscope adapter that it can be held in breast pocket. Its operation is only sampling and sending to host PC. The most of functions of the oscilloscope are processed by host PC. Therefore, oscilloscope adapter can be simplified. This....
The device serves to quickly establish the status of an indicative power cells. I built it for his children, so they can determine the degree of self-discharge batteries in a variety of toys. WAS tester designed to test the fast primary (zinc, alcaline)....
If we have a lot of parallel telephones on a telephone line, we needed a unit that will have the possibility of showing if somebody of the telephone has raised the earphone. Our this possibility give the circuit. The circuit is connected at parallel with the....
The circuit can be tuned to respond to signals between 50 MHz and 500 GHz. The economy model is shown in Fig. 1, and the deluxe model is shown in Fig. 2.The first op amp in each circuit functions as a current-to-voltage converter. In the economy model IClb....
Provides remote control for ac-powered devices by using the beam of a flashlight as a magic wand. The important aspect of this gadget is that it remembers. Activate it once to apply power to a device and it stays on. Activate it a second time and power goes....
