New Circuits Page 238
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This circuit is usable as a Night Lamp when a wall mains socket is not available to plug-in an ever running small neon lamp device. In order to ensure minimum battery consumption, one 1.5V cell is used, and a simple voltage doubler drives a pulsating....
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An input rectangular signal is differentiated and short impulses are formed from its edges. These impulses write the content of counter A to a latch that clears the counter after a very short time. Counter A counts impulses of the frequency fo that are much....
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To keep the gain constant, the circuit used an incandescent pilot light to provide AGC (automatic gain control). As is true for all incandescent bulbs, the pilot light has nonlinear resistance. When you turn on the circuit, the cold lamp`s resistance is low,....
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Dual Channel Relay Board is a simple and convenient way to interface 2 relays for switching application in your project. Input - 12 VDC @ 84 mA. Output - two SPDT relay. Relay specification - 5 A @ 230 VAC. Trigger level - 2 ~ 5 VDC. Berg pins for connecting....
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This new FM transmitter is very easy to make and doesn't need any RF tuning. First of all ,we have used an integrated VCO: The POS150 from Mini-circuits. This excellent RF circuit covers all the FM Band in a voltage range of 4V to 8V. The Kvco factor is very....
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This is a minimum component complete Universal Counter. It can use input frequencies up to 10 MHz at INPUT A and 2 MHz at INPUT B..
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In the typical dynamo charging circuit, B+ and B- are the battery connections. D+ and D- go to the dynamo brushes, while DF is the field connection, with its other end returned to D+ inside the dynamo. Please note that not all dynamos return the field....
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In essence, it uses the same principle as a graphic equaliser, but the simulated inductors are made variable, so the frequency can be swept back and forth. The four 10K pots provide cut (when on the left or anti-clockwise side of centre) or boost, and in the....
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The Linkwitz transform circuit (or EAS principle) will allow any driver to extend to 20 Hz or even lower. A good quick test is to stick the speaker in a box, and drive it to 50 or 100W or so at 20 Hz - you should see a lot of cone movement, a few things will....
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The ATV exciter described here uses a pair of Hamtronics model TA451 2-watt narrow-band FM voice transmitters to develop video and audio carriers on 439.250 MHz and 443.750 MHz. The TA451 is a single board, phase modulated exciter designed for amateur radio....
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This circuit uses inexpensive, common components to generate a precise dial tone for phone applications (see the figure). Ul (an Intel 82C54 timer-counter) generates 350 and 440Hz square waves that are filtered by Rl/Cl and R,JC2, and mixed together by....
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The MAX712 and MAX713 are nickel cadmium (Ni-Cd) battery fast charge controllers which will fast charge batteries from a DC source at least 1V higher than the maximum battery voltage. 1 to 16 series cells can be charged at rates up to 4C. A voltage-slope....
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This circuit enables transistorized items such as radio, cassettes, and other electrical devices to be operated from a car"s electrical supply. The table gives values for resistors and specified diode types fordifferent voltage. Should more than one voltage....
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This circuit, can deliver 3 A or more and a maximum dc voltage ol` a little over 20 V. It is designed around the readily available LM317T adjustable 3-terminal regulator and has a pnp power transistor to boost the current output. The transformer has an 18-V....
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The servo driver is just simply two 4017 decade counters and lots of 0.1" headers. Only populate the A side headers; the B servo bank is optional and will require a few more header pieces. If you received 20 headers, you'll be short two of them. If you....
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Here's a metal detector circuit that frequencies of the two oscillators are then mixed in similar fashion to BFO, to produce an audible heterodyne. On the surface of it, this design would seem to represent little more than a twinned BFO metal detector...
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Following a hunch, the author discovered (or re-discovered?) that all plants carry an electric charge relative to the ground. This charge is more or less constant regardless of the size of the plant - a kind of "background voltage" in nature. This electric....
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The main (and only) job of this circuit is to activate a buzzer or a relay, each time the level of humidity takes a specific value. Main stage is a memory based on a flip-flop consisting of gates and IC1a IC1 b. The output of this step activates an....
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This Alarm can be used to protect your property, Inside or Outside.
And it can protect a Very Large area such as the complete perimeter of your yard.
Be Aware: There are some Possible Drawbacks: Snow or Fog could Block the Beam,
Giving a False Alarm...
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High power LEDs are quickly expanding their reach as the
lightsource of choice for flat panel computer and TV
monitors, TV projection, signage, portable lights and
automotive interior, trim and brake lighting. The input
voltage and LED voltage....
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The following are current regulator circuits that can be used to drive light emitting diodes. As always, take time to do some testing before attempting to use these circuits in actual applications...
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The VLF Converter can be used to pick up signals for the general coverage of shortwave receivers. A number of unusual signals..
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Only one channel is shown, both channels are identical. The input and output RF filter coils and capacitors should be build on the RCA jacks, keep the leads short and use coax to run the signals to the circuitry. The circuit should be build inside of a metal....
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This preamplifier is requirement result of many friends to give a high quality preamplifier, capable to drive high quality power amplifiers with good sound, it`s not however difficult to making, it combines simplicity and handiness. It does not allocate a....
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Not much can be said about how the LM382 works as most of the circuitry is contained within the IC. Most of the frequency-determining components are on the chip—only the capacitors are mounted externally..
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This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light. If the input voltage falls....
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This simple mobile voltage regulator circuit may save your two meter or CB transceiver if the voltage regulator fails. The 2N3055 should be heat sinked if current drawn by the rig is in excess of 2 A on transmit..
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Ul is a dual voltage comparator with open collector outputs. The A side is an oscillator operating at 100kHz, and the B side is part of the regulation circuit that compares a fraction of the output voltage to a reference generated by zener diode D2. The....
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This Project can be used with the three phase Induction motors. The circuit will take the full control of the motor and it will protect the motor from several faults such us over voltage and under voltage and the circuit will switch on the motor under safety....
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Here`s an effective for a temperature sensor to receive power from a 4-to-20 mA loop without actually affecting the loop current (see the figure). This particular temperature sensor IC (AD590F) conducts 1 / when powered by a supply in the range of 4 V to 40....
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The design shown is a simple unit for QRP operation on all authorized frequencies up to 30 MHz. based on a toroidal transformer Tl. The secondary winding of Tl samples a small amount o1 rf power. both forward and reflected, which is divided by the bridge....
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Analog peak detection is accomplished hy repeatedly measuring the input signal with an a/d converter and comparing the current reading with the previous reading. If the current reading is larger than the previous, the current reading is stored in the latch....
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The IBM PC debugger plugs into the PC"s math-coprocessor socket.The 8288 bus controller, IC1, regenerates control signals from the processor"s status signals, SO, Sl, and S2. Reset LED Dllights if reset is active and holding the processor. Clock status LED....
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The 8052.com SBC is a single-board computer designed to be both useful and instructive in illustrating certain concepts commonly encountered in 8052-based development...
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TCA965 window discriminator IC allows the potentiometers RVl and RV2 to set up a window height and window width respectively. Rl and thermistor THl for a potential divider connected across the supply lines. Rl is chosen such that at ambient temperature the....
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Ql and Q2 form a constant current drive defined by R2. (I approximates to the reciprocal of R2 in the circuit shown for values of I greater than 1 amp). The pulse current is drawn from Cl which is recharged during the time between pulses via Rl.
..
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This circuit is a general-purpose 10-W audio amplifier for moderate-power PA or modulator use in an AM transmitter. With higher voltages and a change in bias resistors, up to 30 W can be obtained...
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The amplifier is based on an integrated circuit TDA2822M. With this circuit can be built amplifier with up to 2 1 W. This much power circuit is able to supply only at peak times, the continuous excitation would not be able uchladit. Involvement of the....
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The modern mechanic switches are improved concerning of old technology. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. For he....
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A 9-V wall adapter supplies Vm. IC2 contains a low-battery detector circuit that senses l7IN by means of R6 and R7. The detector output Cpin 7) drives an inverter (Ql), which in turn drives the shut-down inputs Ic of 1C1 and SHDN of IC2. These inputs have....
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This Project is used to control our household electrical devices from any where through the cell phone. The circuit consists of a DTMF tone detector and a powerful 8 bit Microcontroller AT89S52. The microcontroller controls all the system. In this project we....
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Because power for the circuit is obtained from the car"s side lights, the circuit can"t oscillate unless the lights are o..
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The project is "Motorized Curtain" with Remote control. It is made up of MCU ATMEGA328 with Arduino BootLoader, motor driver L293D ( i used L293B with external diodes, because i couldn't find L293D ), IR Receiver TSOP 1738, DC Motor from an old printer and....
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Capacitor C1 is charged through timing resistor R1 when the clock output is high. When C1 reaches the upper threshold voltage, the output signal decreases, and then C1 discharges through R1 until its voltage reaches the lower threshold point. When this....
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The ear protector is actually a peak audio-detector/shutdown circuit that disables the amplifier through its chip-disable input when the output volume of an amplifier reaches the set level. The circuit, although intended for the MC34119 amplifier,..
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The circuit is not particularly susceptible to motor transients and supports FULL STEPS FORWARD, FULL STEPS REVERSE, ACTIVE HOLD, and POWER OFF aka RELEASED. If the motor does not turn then swap around the leads of ONE of the two coils. To reverse the sense....
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The 555 is wired as an astable and the capacitor is charged only through the 4,7Kohm trimmer (notice the diode) and discharged only through the 2.2 Kohm trimmer, making the duty cycle full adjustable. The square wave is then feed in a totem pole made up of a....
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This is an image Schematic. No Description available...
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The CPU is an AMD K5 running 75 MHz. Theres 16 meg ram, and the operating system is Linux (Red Hat 5.2). MPG123 handles the MP3 decoding, and I wrote a control program in Perl.
I built the remote control in an old Blaupunkt CD-changer remote case which I....
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This low-voltage high-current output, sWitching de power supply is running off the 220-Vac input. In this circuit, an ST2 diac relaxation oscillator, Q3, Cl, and the diac, initiates conduction of the output switching transistor Ql, the on-time of which is....
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The control voltage Vc easily sets the cutoff frequency w0 of this state-variable filter to any desired value, from about 1.7 MHz up to 5 MHz, with a BB 204 varicap and R = 100 KO. Vc can range from 0 to 28 V. This range changes the capacitance of the....
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When used as a stand-alone device, ZN1034E from Ferranti can provide timed intervals ranging from 1 second to 19 days, although the rc time constant is only 220 seconds. The ZN1034E includes an internal voltage regulator, an oscillator, and a 12-stage....
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A two-tone generator that is alternately switched ON provides a high/low output as might be heard from a traffic vehicle like a police car or ambulance. IC1, CD4011, quad 2-input NAND gate is a two-tone oscillator in which each side, pins 1 through 7 and 8....
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The uA2240 timer/counter, combined with aprecision resistor ladder network and an op amp, form the staircase generator. In the astable mode, once a trigger pulse is applied, the uA2240 operates continuously until it receives a reset pulse. The trigger....
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The turn-on and turn-off characteristics of two complementary transistors can be combined to attain nonselective frequency tripling. The resulting circuit handles any periodic waveform with nonvertical sides. Each input signal peak produces three output....
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These are modulator circuits for modulation of video signals on a VHF/UHF carrier. The circuits require a 5 V power supply and few external components for the negative modulation mode. For positive modulation an external clamp circuit is required...
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Circuit of a digital volume control using six discrete ICs, including a 5V regulator, is presented. IC1 (555) is configured to function as astable flip-flop. Its frequency or period may be adjusted by proper choice of resistors R44, R45 and capacitor C6....
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GSM based Automatic meter reading, or AMR, is the technology of automatically collecting data from energy meter and transferring that data to a central database for billing and/or analyzing. The Transmitter is connected to the meter and it counts the pulses....
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The circuit will work without the extra components, but for reverse polarity protection a 1N5400 diode is provided at the input, extra smoothing being provided by C1. The output stage includes C2 for extra filtering, if powering a logic circuit than a 100nF....
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Intended as a replacement for generally poorly regulated "wall-type" ac/dc adapters, this circuit offers superior p..
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This little circuit will help you to scan the line of a 220V live wire in the wall. The FET gate is connected to a capacitive metal sensor (which is usually a simple metal plate). When you hold the sensor close to the wall, the LED will indicate the current....
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With this circuit mounted in or near every phone in the house, it will allow users to know if the phone is being used and not to pick up the phone. When a phone is taken off hook, the voltage across the tip and ring terminals drops to 10 volts or less. This....
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This RS-232 type line receiver to drive CMOS logic uses a Schmitt-trigger feedback network to ~give about 1-V input hysteresis for added noise immunity. A possible problem in an interface which connects two pieces of equipment, each plugged into a different....
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The LED is the CSL310L which contains a red LED and a green LED connected back to back and mounted close together in a single moulding. The LED can emit red or^green light by controlling the polarity of the applied voltage and if the polarity is switched at....
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A tapped-coil Colpitis oscillator is used at Ql to provide four tuning ranges from 1.7 to 3.131Hz, 3.0 to 5.6 MHz, 5.0 to 12 MHz and 11.5 to 31 MHz. A Zener diode (D2) is used at Ql to lower the operating voltage of the oscillator. A small value capacitor is....
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CI in series with the crystal may be used to adjust the oscillator output frequency· Value may range between 20 pF and 0.01 µ¥, or may be a trimmer capacitor and will approximately equal the crystal load capacitance. X values are approximate and can vary....
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This is a Full wave omni directional vertical ground plane antenna for 2-meters plan with 250 watts max power...
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Transistors Ql and Q2 and their associated components provide: a low-impedance output with the necessary power to drive the output stages, give increased gain tohigh frequencies, and peaking the video for enhanced transient response. Emitter followers Q3,....
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This is a basic Buzzer driver circuit with resonance frequncy approximatly 5 Khz, 85 dBA. It operates on 3 to 28 v DC at 6mA...
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Controller for brushless
and sensorless motors, with active rpm control # Active rpm control
# Car mode
# Proportional brake
# Active freeweehling
# Updates via Internet available..
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This circuit can control a small DC motor, like the one in a tape recorder. When both the points A & B are "HIGH" Q1 and Q2 are in saturation. Hence the bases of Q3 to Q6 are grounded. Hence Q3,Q5 are OFF and Q4,Q6 are ON . The voltages at both the motor....
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The circuit in Figure 1 can intelligently control ac or dc current when connected in series with a load. The circuit "steals" its power by turning off the load at a low duty cycle. The switch uses the MOSFETs` parasitic body diode to its advantage. While the....
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A high impedance input is provided by Ql, a general purpose field effect transistor..
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The circuit is a simple rf-actuated switch which will respond to any strong field in the region of the pickup wire. The length of the wire will depend on how much coupling is needed, but a 250-mm length wrapped around the outside of the coaxial cable....
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The pulse repetition rate is relatively insensitive to temperature, and power supply voltage and is a linear function of V1N, the modulating voltage. Useful information transfer was obtained in free air ranges of 12 feet (~ 4m). Greater range can also be....
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The circuit in Figure 2 shows a 16-channel, AMI-encoded RF transmitter for data rates as high as 28.8 kbps. The circuit operates in the unlicensed (FCC Part 15) 902- to 928-MHz industrial, scientific, and medical (ISM) band and is reliable for open-field....
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This circuit is used to convert a mono audio signal into a stereo signal that can be panned between the left and right channel by a 0-10V control signal, it is intended for analog synthesizer systems...
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When digital data is transmitted over long lines (longer than 1 meter), proper transfer is often disturbed by the parasitic effects of ground level shifts and ground loops, as well as by extraneous noise picked up along the way. An optocoupler, such as the....
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The Astable Multivibrator, which is generally used as a signal generator, is once again used here to generate the desired frequencies. It is an excellent example of the fact, how versatile simple basic electronic circuit can be. It seems quite obvious then,....
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Uses CA3130 BiMOS op amp that operates at a frequency of 1 kHz. With rail-to-rail output swing, frequency is independent of supply voltage, device, and temperature. ..
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This project was begun as a means to charge and cycle NiCad batteries but has become a versatile tool for experiments requiring either a controlled voltage up to +30V and/or a current of +/- 2.5 Amps. If all you want to do is charge and recycle NiCad....
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The metal locator uses a one-transistor oscillator and an AM radio to detect metal. Transistor Ql is a pnp transistor that is connected to an oscillator. Resistor Rl provides the correct base bias and capacitors C3 and 04 and the search coil determine the....
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a more complex detector circuit which turns the relay on for an adjustable period of time. When the beam is broken, the LED goes on, your effect is powered, and capacitor C1 begins charging. As C1 is charging, the transistor will be kept on. Once C1 is....
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The LTC3205 is a highly integrated multidisplay LED controller. The part contains a high efficiency, low noise fractional step-up/step-down charge pump to provide power for both main and sub white LED displays plus an RGB color LED display. The LTC3205....
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1 kHz is a commonly used test frequency, and I resolved to see if I could make an inductance meter that uses a 1 kHz test signal at a low level. I also wanted to use a low level test signal so that the test current would have a minimal effect on the....
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The circuit presented here uses linear shunt regulation. Simply spoken, it burns off all excess energy from the panel, keeping output voltage constant. At times when the solar panel output is equal or greater than the load, and the battery is fully charged,....
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This .circuit for starting arc jets and controlling them in steady operation is capable of high power efficiency and can be constructed in a lightweight form. The design comprises a pulse-width-modulated power converter, which is configured in a closed....
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A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes. This timer circuit is similar to the 5 to 30 minute timer except that when switch S1 is closed, the on/off action of the circuit will continue....
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This is my electronic combination lock to use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. This relay can operate a power-to-open type....
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The baby-alert receiver is comprised of three transistors: Q2, which is configured as a high-gain linear amplifier; Q3, which serves as both an amplifier and detector; and Q4. which is essentially used as a switch; and a few additional components...
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This is an image Schematic. No Description available...
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With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum....
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The linear dual tracking power supply, shown in the schematic, provides 0-15 volts, at 1/4 amp, maximum, using a discrete transistor regulator with op-amp feedback to control the output voltage. The supply was constructed in 1975; the negative ouput voltage....
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This circuit allows a remote microprocessor to be reset by a controlling host over a remote RS-232 or similar protocol serial line. With the use of a program loader on the remote host, a program may be downloaded and run. This allows a target processor to....
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This Field Strength Meter has been specially designed for our FM bugs. It is capable of detecting very low power transmitters and will assist enormously in peaking many of our FM transmitters that have a coil in the output stage that can be adjusted for....
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A 741 op amp is used with 100% ac and dc feedback to provide a typical input impedance of 1011 ohm and unity gain. To avoid hum and rf pickup the input leads should be kept as short as possible and the circuit should be mounted in a small grounded case.....
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This is a very basic circuit for fading video signal shown in Eletor Electronics magazine. You can use this between two video equipments. The circuit is so simple that the impedance matching and some other things are not exactly correct, so might not always....
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Voltage reference integrated circuits are widely used to
establish accurate and stable voltages in analog circuits.
While calibration-grade references are based on buried
Zener diode technology (or even more exotic methods),
the ubiquitous band-gap....
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This circuit is a simple ultraviolate light that can be powered by a 6 volt battery or power supply (such as the power supply on the "Circuits" page) that is capable of supplying 1 or more amps...
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When the digital logic level at the control input is low, the PIN diode is forward-biased by the CMOS gates. The two 1-KO bias resistors limit this current to the PIN diode"s safe forward current limit. In this state, the switch is on. When the control....
This circuit is usable as a Night Lamp when a wall mains socket is not available to plug-in an ever running small neon lamp device. In order to ensure minimum battery consumption, one 1.5V cell is used, and a simple voltage doubler drives a pulsating....
An input rectangular signal is differentiated and short impulses are formed from its edges. These impulses write the content of counter A to a latch that clears the counter after a very short time. Counter A counts impulses of the frequency fo that are much....
To keep the gain constant, the circuit used an incandescent pilot light to provide AGC (automatic gain control). As is true for all incandescent bulbs, the pilot light has nonlinear resistance. When you turn on the circuit, the cold lamp`s resistance is low,....
Dual Channel Relay Board is a simple and convenient way to interface 2 relays for switching application in your project. Input - 12 VDC @ 84 mA. Output - two SPDT relay. Relay specification - 5 A @ 230 VAC. Trigger level - 2 ~ 5 VDC. Berg pins for connecting....
This new FM transmitter is very easy to make and doesn't need any RF tuning. First of all ,we have used an integrated VCO: The POS150 from Mini-circuits. This excellent RF circuit covers all the FM Band in a voltage range of 4V to 8V. The Kvco factor is very....
This is a minimum component complete Universal Counter. It can use input frequencies up to 10 MHz at INPUT A and 2 MHz at INPUT B..
In the typical dynamo charging circuit, B+ and B- are the battery connections. D+ and D- go to the dynamo brushes, while DF is the field connection, with its other end returned to D+ inside the dynamo. Please note that not all dynamos return the field....
In essence, it uses the same principle as a graphic equaliser, but the simulated inductors are made variable, so the frequency can be swept back and forth. The four 10K pots provide cut (when on the left or anti-clockwise side of centre) or boost, and in the....
The Linkwitz transform circuit (or EAS principle) will allow any driver to extend to 20 Hz or even lower. A good quick test is to stick the speaker in a box, and drive it to 50 or 100W or so at 20 Hz - you should see a lot of cone movement, a few things will....
The ATV exciter described here uses a pair of Hamtronics model TA451 2-watt narrow-band FM voice transmitters to develop video and audio carriers on 439.250 MHz and 443.750 MHz. The TA451 is a single board, phase modulated exciter designed for amateur radio....
This circuit uses inexpensive, common components to generate a precise dial tone for phone applications (see the figure). Ul (an Intel 82C54 timer-counter) generates 350 and 440Hz square waves that are filtered by Rl/Cl and R,JC2, and mixed together by....
The MAX712 and MAX713 are nickel cadmium (Ni-Cd) battery fast charge controllers which will fast charge batteries from a DC source at least 1V higher than the maximum battery voltage. 1 to 16 series cells can be charged at rates up to 4C. A voltage-slope....
This circuit enables transistorized items such as radio, cassettes, and other electrical devices to be operated from a car"s electrical supply. The table gives values for resistors and specified diode types fordifferent voltage. Should more than one voltage....
This circuit, can deliver 3 A or more and a maximum dc voltage ol` a little over 20 V. It is designed around the readily available LM317T adjustable 3-terminal regulator and has a pnp power transistor to boost the current output. The transformer has an 18-V....
The servo driver is just simply two 4017 decade counters and lots of 0.1" headers. Only populate the A side headers; the B servo bank is optional and will require a few more header pieces. If you received 20 headers, you'll be short two of them. If you....
Here's a metal detector circuit that frequencies of the two oscillators are then mixed in similar fashion to BFO, to produce an audible heterodyne. On the surface of it, this design would seem to represent little more than a twinned BFO metal detector...
Following a hunch, the author discovered (or re-discovered?) that all plants carry an electric charge relative to the ground. This charge is more or less constant regardless of the size of the plant - a kind of "background voltage" in nature. This electric....
The main (and only) job of this circuit is to activate a buzzer or a relay, each time the level of humidity takes a specific value. Main stage is a memory based on a flip-flop consisting of gates and IC1a IC1 b. The output of this step activates an....
This Alarm can be used to protect your property, Inside or Outside. And it can protect a Very Large area such as the complete perimeter of your yard. Be Aware: There are some Possible Drawbacks: Snow or Fog could Block the Beam, Giving a False Alarm...
The following are current regulator circuits that can be used to drive light emitting diodes. As always, take time to do some testing before attempting to use these circuits in actual applications...
The VLF Converter can be used to pick up signals for the general coverage of shortwave receivers. A number of unusual signals..
This preamplifier is requirement result of many friends to give a high quality preamplifier, capable to drive high quality power amplifiers with good sound, it`s not however difficult to making, it combines simplicity and handiness. It does not allocate a....
Not much can be said about how the LM382 works as most of the circuitry is contained within the IC. Most of the frequency-determining components are on the chip—only the capacitors are mounted externally..
This simple and slightly odd circuit can clearly show the level of the supply voltage (in a larger device): as long as the indicator has good 12 volts at its input, LED1 gives steady, uninterrupted (for the naked eye) yellow light. If the input voltage falls....
This simple mobile voltage regulator circuit may save your two meter or CB transceiver if the voltage regulator fails. The 2N3055 should be heat sinked if current drawn by the rig is in excess of 2 A on transmit..
Ul is a dual voltage comparator with open collector outputs. The A side is an oscillator operating at 100kHz, and the B side is part of the regulation circuit that compares a fraction of the output voltage to a reference generated by zener diode D2. The....
This Project can be used with the three phase Induction motors. The circuit will take the full control of the motor and it will protect the motor from several faults such us over voltage and under voltage and the circuit will switch on the motor under safety....
Here`s an effective for a temperature sensor to receive power from a 4-to-20 mA loop without actually affecting the loop current (see the figure). This particular temperature sensor IC (AD590F) conducts 1 / when powered by a supply in the range of 4 V to 40....
The design shown is a simple unit for QRP operation on all authorized frequencies up to 30 MHz. based on a toroidal transformer Tl. The secondary winding of Tl samples a small amount o1 rf power. both forward and reflected, which is divided by the bridge....
Analog peak detection is accomplished hy repeatedly measuring the input signal with an a/d converter and comparing the current reading with the previous reading. If the current reading is larger than the previous, the current reading is stored in the latch....
The IBM PC debugger plugs into the PC"s math-coprocessor socket.The 8288 bus controller, IC1, regenerates control signals from the processor"s status signals, SO, Sl, and S2. Reset LED Dllights if reset is active and holding the processor. Clock status LED....
TCA965 window discriminator IC allows the potentiometers RVl and RV2 to set up a window height and window width respectively. Rl and thermistor THl for a potential divider connected across the supply lines. Rl is chosen such that at ambient temperature the....
Ql and Q2 form a constant current drive defined by R2. (I approximates to the reciprocal of R2 in the circuit shown for values of I greater than 1 amp). The pulse current is drawn from Cl which is recharged during the time between pulses via Rl. ..
This circuit is a general-purpose 10-W audio amplifier for moderate-power PA or modulator use in an AM transmitter. With higher voltages and a change in bias resistors, up to 30 W can be obtained...
The amplifier is based on an integrated circuit TDA2822M. With this circuit can be built amplifier with up to 2 1 W. This much power circuit is able to supply only at peak times, the continuous excitation would not be able uchladit. Involvement of the....
The modern mechanic switches are improved concerning of old technology. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. For he....
A 9-V wall adapter supplies Vm. IC2 contains a low-battery detector circuit that senses l7IN by means of R6 and R7. The detector output Cpin 7) drives an inverter (Ql), which in turn drives the shut-down inputs Ic of 1C1 and SHDN of IC2. These inputs have....
This Project is used to control our household electrical devices from any where through the cell phone. The circuit consists of a DTMF tone detector and a powerful 8 bit Microcontroller AT89S52. The microcontroller controls all the system. In this project we....
Because power for the circuit is obtained from the car"s side lights, the circuit can"t oscillate unless the lights are o..
The project is "Motorized Curtain" with Remote control. It is made up of MCU ATMEGA328 with Arduino BootLoader, motor driver L293D ( i used L293B with external diodes, because i couldn't find L293D ), IR Receiver TSOP 1738, DC Motor from an old printer and....
Capacitor C1 is charged through timing resistor R1 when the clock output is high. When C1 reaches the upper threshold voltage, the output signal decreases, and then C1 discharges through R1 until its voltage reaches the lower threshold point. When this....
The ear protector is actually a peak audio-detector/shutdown circuit that disables the amplifier through its chip-disable input when the output volume of an amplifier reaches the set level. The circuit, although intended for the MC34119 amplifier,..
The circuit is not particularly susceptible to motor transients and supports FULL STEPS FORWARD, FULL STEPS REVERSE, ACTIVE HOLD, and POWER OFF aka RELEASED. If the motor does not turn then swap around the leads of ONE of the two coils. To reverse the sense....
The 555 is wired as an astable and the capacitor is charged only through the 4,7Kohm trimmer (notice the diode) and discharged only through the 2.2 Kohm trimmer, making the duty cycle full adjustable. The square wave is then feed in a totem pole made up of a....
The CPU is an AMD K5 running 75 MHz. Theres 16 meg ram, and the operating system is Linux (Red Hat 5.2). MPG123 handles the MP3 decoding, and I wrote a control program in Perl. I built the remote control in an old Blaupunkt CD-changer remote case which I....
This low-voltage high-current output, sWitching de power supply is running off the 220-Vac input. In this circuit, an ST2 diac relaxation oscillator, Q3, Cl, and the diac, initiates conduction of the output switching transistor Ql, the on-time of which is....
The control voltage Vc easily sets the cutoff frequency w0 of this state-variable filter to any desired value, from about 1.7 MHz up to 5 MHz, with a BB 204 varicap and R = 100 KO. Vc can range from 0 to 28 V. This range changes the capacitance of the....
When used as a stand-alone device, ZN1034E from Ferranti can provide timed intervals ranging from 1 second to 19 days, although the rc time constant is only 220 seconds. The ZN1034E includes an internal voltage regulator, an oscillator, and a 12-stage....
A two-tone generator that is alternately switched ON provides a high/low output as might be heard from a traffic vehicle like a police car or ambulance. IC1, CD4011, quad 2-input NAND gate is a two-tone oscillator in which each side, pins 1 through 7 and 8....
The uA2240 timer/counter, combined with aprecision resistor ladder network and an op amp, form the staircase generator. In the astable mode, once a trigger pulse is applied, the uA2240 operates continuously until it receives a reset pulse. The trigger....
The turn-on and turn-off characteristics of two complementary transistors can be combined to attain nonselective frequency tripling. The resulting circuit handles any periodic waveform with nonvertical sides. Each input signal peak produces three output....
These are modulator circuits for modulation of video signals on a VHF/UHF carrier. The circuits require a 5 V power supply and few external components for the negative modulation mode. For positive modulation an external clamp circuit is required...
Circuit of a digital volume control using six discrete ICs, including a 5V regulator, is presented. IC1 (555) is configured to function as astable flip-flop. Its frequency or period may be adjusted by proper choice of resistors R44, R45 and capacitor C6....
GSM based Automatic meter reading, or AMR, is the technology of automatically collecting data from energy meter and transferring that data to a central database for billing and/or analyzing. The Transmitter is connected to the meter and it counts the pulses....
The circuit will work without the extra components, but for reverse polarity protection a 1N5400 diode is provided at the input, extra smoothing being provided by C1. The output stage includes C2 for extra filtering, if powering a logic circuit than a 100nF....
Intended as a replacement for generally poorly regulated "wall-type" ac/dc adapters, this circuit offers superior p..
This little circuit will help you to scan the line of a 220V live wire in the wall. The FET gate is connected to a capacitive metal sensor (which is usually a simple metal plate). When you hold the sensor close to the wall, the LED will indicate the current....
With this circuit mounted in or near every phone in the house, it will allow users to know if the phone is being used and not to pick up the phone. When a phone is taken off hook, the voltage across the tip and ring terminals drops to 10 volts or less. This....
This RS-232 type line receiver to drive CMOS logic uses a Schmitt-trigger feedback network to ~give about 1-V input hysteresis for added noise immunity. A possible problem in an interface which connects two pieces of equipment, each plugged into a different....
The LED is the CSL310L which contains a red LED and a green LED connected back to back and mounted close together in a single moulding. The LED can emit red or^green light by controlling the polarity of the applied voltage and if the polarity is switched at....
A tapped-coil Colpitis oscillator is used at Ql to provide four tuning ranges from 1.7 to 3.131Hz, 3.0 to 5.6 MHz, 5.0 to 12 MHz and 11.5 to 31 MHz. A Zener diode (D2) is used at Ql to lower the operating voltage of the oscillator. A small value capacitor is....
CI in series with the crystal may be used to adjust the oscillator output frequency· Value may range between 20 pF and 0.01 µ¥, or may be a trimmer capacitor and will approximately equal the crystal load capacitance. X values are approximate and can vary....
Transistors Ql and Q2 and their associated components provide: a low-impedance output with the necessary power to drive the output stages, give increased gain tohigh frequencies, and peaking the video for enhanced transient response. Emitter followers Q3,....
This is a basic Buzzer driver circuit with resonance frequncy approximatly 5 Khz, 85 dBA. It operates on 3 to 28 v DC at 6mA...
This circuit can control a small DC motor, like the one in a tape recorder. When both the points A & B are "HIGH" Q1 and Q2 are in saturation. Hence the bases of Q3 to Q6 are grounded. Hence Q3,Q5 are OFF and Q4,Q6 are ON . The voltages at both the motor....
A high impedance input is provided by Ql, a general purpose field effect transistor..
The circuit is a simple rf-actuated switch which will respond to any strong field in the region of the pickup wire. The length of the wire will depend on how much coupling is needed, but a 250-mm length wrapped around the outside of the coaxial cable....
The pulse repetition rate is relatively insensitive to temperature, and power supply voltage and is a linear function of V1N, the modulating voltage. Useful information transfer was obtained in free air ranges of 12 feet (~ 4m). Greater range can also be....
The circuit in Figure 2 shows a 16-channel, AMI-encoded RF transmitter for data rates as high as 28.8 kbps. The circuit operates in the unlicensed (FCC Part 15) 902- to 928-MHz industrial, scientific, and medical (ISM) band and is reliable for open-field....
This circuit is used to convert a mono audio signal into a stereo signal that can be panned between the left and right channel by a 0-10V control signal, it is intended for analog synthesizer systems...
When digital data is transmitted over long lines (longer than 1 meter), proper transfer is often disturbed by the parasitic effects of ground level shifts and ground loops, as well as by extraneous noise picked up along the way. An optocoupler, such as the....
The Astable Multivibrator, which is generally used as a signal generator, is once again used here to generate the desired frequencies. It is an excellent example of the fact, how versatile simple basic electronic circuit can be. It seems quite obvious then,....
Uses CA3130 BiMOS op amp that operates at a frequency of 1 kHz. With rail-to-rail output swing, frequency is independent of supply voltage, device, and temperature. ..
This project was begun as a means to charge and cycle NiCad batteries but has become a versatile tool for experiments requiring either a controlled voltage up to +30V and/or a current of +/- 2.5 Amps. If all you want to do is charge and recycle NiCad....
The metal locator uses a one-transistor oscillator and an AM radio to detect metal. Transistor Ql is a pnp transistor that is connected to an oscillator. Resistor Rl provides the correct base bias and capacitors C3 and 04 and the search coil determine the....
a more complex detector circuit which turns the relay on for an adjustable period of time. When the beam is broken, the LED goes on, your effect is powered, and capacitor C1 begins charging. As C1 is charging, the transistor will be kept on. Once C1 is....
The LTC3205 is a highly integrated multidisplay LED controller. The part contains a high efficiency, low noise fractional step-up/step-down charge pump to provide power for both main and sub white LED displays plus an RGB color LED display. The LTC3205....
1 kHz is a commonly used test frequency, and I resolved to see if I could make an inductance meter that uses a 1 kHz test signal at a low level. I also wanted to use a low level test signal so that the test current would have a minimal effect on the....
The circuit presented here uses linear shunt regulation. Simply spoken, it burns off all excess energy from the panel, keeping output voltage constant. At times when the solar panel output is equal or greater than the load, and the battery is fully charged,....
This .circuit for starting arc jets and controlling them in steady operation is capable of high power efficiency and can be constructed in a lightweight form. The design comprises a pulse-width-modulated power converter, which is configured in a closed....
A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes. This timer circuit is similar to the 5 to 30 minute timer except that when switch S1 is closed, the on/off action of the circuit will continue....
This is my electronic combination lock to use with an outdoor gate. The functionality is implemented in software. It turns on a relay (usually to open a door) for a few seconds if someone enters the valid code. This relay can operate a power-to-open type....
The baby-alert receiver is comprised of three transistors: Q2, which is configured as a high-gain linear amplifier; Q3, which serves as both an amplifier and detector; and Q4. which is essentially used as a switch; and a few additional components...
With reference to the schematic, lamp, LP2, is a power-on indicator. The other lamp (lower) lights when the unit reaches its preset current limit. R5, C2, and Q10 (TO-3 case) operate as a capacitor multiplier. The 36 volt zener across C2 limits the maximum....
The linear dual tracking power supply, shown in the schematic, provides 0-15 volts, at 1/4 amp, maximum, using a discrete transistor regulator with op-amp feedback to control the output voltage. The supply was constructed in 1975; the negative ouput voltage....
This circuit allows a remote microprocessor to be reset by a controlling host over a remote RS-232 or similar protocol serial line. With the use of a program loader on the remote host, a program may be downloaded and run. This allows a target processor to....
This Field Strength Meter has been specially designed for our FM bugs. It is capable of detecting very low power transmitters and will assist enormously in peaking many of our FM transmitters that have a coil in the output stage that can be adjusted for....
A 741 op amp is used with 100% ac and dc feedback to provide a typical input impedance of 1011 ohm and unity gain. To avoid hum and rf pickup the input leads should be kept as short as possible and the circuit should be mounted in a small grounded case.....
This circuit is a simple ultraviolate light that can be powered by a 6 volt battery or power supply (such as the power supply on the "Circuits" page) that is capable of supplying 1 or more amps...
When the digital logic level at the control input is low, the PIN diode is forward-biased by the CMOS gates. The two 1-KO bias resistors limit this current to the PIN diode"s safe forward current limit. In this state, the switch is on. When the control....
