Circuit Diagram

FM_LIGHT_BEAM_TRANSMITTER

Published:2009/6/16 23:52:00 Author:May

This transmitter uses two-stage amplifier Q1/Q2 to frequency modulate an NE555 (configured as a VCO) operating at about 50 kHz. The resultant FM-modulated pulse train is converted to light pulses via LED1 through LED4, driven by Q3 and Q4.   (View)

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FM_LIGHT_BEAM_RECEIVER

Published:2009/6/16 23:51:00 Author:May

This receiver will pick up IR or light beams that are frequency modulated on a 50-kHz carrier Q2/Q1/Q3/Q4 from an active filter and amplifier and differential amp Q5/Q6 provide more gain.   (View)

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MODULATED_LIGHT_RECEIVER

Published:2009/6/16 23:48:00 Author:May

Using a phototransistor, this receiver will detect and demodulate a modulated light beam. R6 af-fects sensitivity.   (View)

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36_LED_Flasher_Driver

Published:2009/6/16 23:48:00 Author:May

Originally intended as a 3-bell animation circuit for Christmas decorations, the circuit can be used for many other purposes that require a flasher of this kind. By re-connerting U2(see the data manual), more than three outputs can be be obtained.   (View)

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MODULATED_LIGHT_TRANSMITTER

Published:2009/6/16 23:48:00 Author:May

A light-bulb filament can be modulated with audio as a method of optical transmission. Ampli-fier Q1/Q2/Q3 drives emitter-follower TR4. Adjust R10 for the Q point (light bulb) giving best results.It should have a filament with low thermal inertia for best audio responses.   (View)

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SIMPLE_LIE_DETECTOR

Published:2009/6/16 23:46:00 Author:May

The circuit uses a two-transistor direct-coupled oscillator that has a frequency determined by C1, R2, and the (skin) resistance across the touch pads. Since C1 and R2 are fixed values, only the skin resistance across the touch pads can vary the sound of the oscillator. To sustain oscillations, C1 feeds a portion of the output from Q2 back to the input of Q1 through resistor R1.Transistor Ql is an npn type and transistor Q2 is a pnp type. The output of Q2 is fed into a small speaker. The circuit relies on the fact that the human skin conducts electricity. C1 0.01-μF CapacitorQ1 2N3904 TransistorQ2 2N3906 TransistorR1 4.7kΩ ResistorR2 85kΩ Resistor   (View)

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LASER_POWER_SUPPLY

Published:2009/6/16 23:39:00 Author:May

This supply generates an initial high voltage for ignition purposes. After ignition, the supply gen-erates about 1300 to 1500 V. If a higher ignition voltage (than the 6000 V supplied) is necessary, more multiplier stages can be added to D5 and D8.   (View)

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FANTASTIC_SIMULATED_LASER

Published:2009/6/16 23:37:00 Author:May

The circuit uses a 555 timer IC to power an ultrabright LED. The output is a pulsing red light that can be projected using lenses. An ultrabright Stanley LED, capable of 300-millicandle output, is tied to pin 3 of the 555 timer IC. That IC has been configured as an astable multivibrator. The fre-quency of this multivibrator is controlled by R1, R2, C1, and P1. You can vary the frequency by ad-justing P1, which changes the output from a slow blinking to a fast pulsating light. Resistor R3 is used to limit the current flowing into the circuit to a safe value, to prevent the LED and the IC from bum-ing out. Switch S1 applies power to the circuit when its button is pressed.   (View)

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HIGH_VOLTAGE_POWER_SUPPLY

Published:2009/6/16 23:37:00 Author:May

The high-voltage power supply is a CMOS-based oscillator that pulses a high-voltage ignition transformer. The transformer output is around 20 kV.   (View)

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Sequential_Flasher

Published:2009/6/16 23:36:00 Author:May

A 555 timer, IC1, drives a 4017 CMOS decade counter. Each of the 4017's first four outputs drives a CA3079 zero-voltage switch. Pin 9 of the CA3079 is used to inhibit output from pin 4, thereby disabling the string of pulses that the IC normally delivers. Those pulses occur every 8.3 ms, i.e., at a rate of 120 Hz. Each pulse has a width of 120 μs. Because of the action of the CA3079, the lamps connected to the triacs turn on and off near the zero crossing of the ac waveform. Switching at that point increases lamp life by reducing an inrush of current that would happen if the lamp were turned on near the high point of the ac waveform. In ad-dition, switching at the zero crossing reduces radio frequency interference (RFI) considerably. Cau-tion: The CA3079s are driven directly from the 117-Vac power line, so use care.   (View)

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HANDHELD_LASER

Published:2009/6/16 23:35:00 Author:May

A laser diode TOLD9200 (Toshiba) is used as a source of laser light. Q3, Q2, and S1 form a touch switch to control the laser. L1 is an RF pickup coil to pick up energy from an RF-type battery charger.It is 10 tums of #18 wire on a 1/2 diameter.   (View)

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LASER_POWER_SUPPLY_AND_STARTING_CIRCUIT

Published:2009/6/16 23:34:00 Author:May

This circuit delivers 10 kV peak, then limits current to 7.5 mA @ 2 kV. The resistors shown provide ballasting. The starting circuit cannot maintain the 10 kV under load and appears as a seriespass circuit with little drop in voltage.   (View)

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EFFICIENT_LASER_SUPPLY

Published:2009/6/16 23:32:00 Author:May

Driving Helium-Neon Lasers can be simplified considerably using this power-supply configura-tion. When power is applied, the laser doesn't conduct and the voltage across the 190-Ω resistor is zero. However, a resonant circuit and a voltage tripler then produces over 10 kV to turn on the laser.   (View)

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NEGATIVE_ION_GENERATOR

Published:2009/6/16 23:31:00 Author:May

This oscillator-driver induces a high voltage in the windings of T2.   (View)

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POWER_MOSFET_INVERTER

Published:2009/6/16 23:29:00 Author:May

T1 is a suitable transformer for the voltage desired, with a 12.6-V CT winding.   (View)

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dc_to_ac_INVERTER

Published:2009/6/16 23:28:00 Author:May

A multivibrator circuit drives a pair of 2N3055 power transistors transformer with a 120-V primary.   (View)

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DIGITAL_INVERTER

Published:2009/6/16 23:27:00 Author:May

A CMOS digital inverter is formed by con-necting two MOSFETS, as shown.   (View)

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250_W_INVERTER

Published:2009/6/16 23:27:00 Author:May

A 555 timer (IC1) generates a 120-Hz signal that is fed to a CD4013BE flip-flop (IC1-a), which divides the input frequency by two to generate a 60-Hz clocking frequency for the FET array (Q1 through Q6). Transformer T1 is a 12-/24-V center-tapped 60-Hz transformer of suitable size.   (View)

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MICROCOMPUTER_TO_TRIAC_INTERFACE

Published:2009/6/16 23:16:00 Author:May

A microcomputer-to-triac interface uses a phototriac optoisolator to let safety-isolated logic sig-nals directly control high-power loads. Depending on the input waveforms and the load, this circuit can be used in either an on/off switch or a proportional phase control. A low input powers the lamp.   (View)

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RECEIVER_INTERFACE_CIRCUIT_FOR_PREAMPS

Published:2009/6/16 23:05:00 Author:May

The purpose of the receiver/interface circuit is to pass RF to the receiver through capacitor C9, while adding dc power to the feedline through R2 and RF choke L7.   (View)

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