Amplificadores
Audible Alarms Circuits
Audio Circuits
Buffer Circuits
Burglar Circuits
Capacitance Circuits
Clock Circuits
Coil Q Tester
Converters
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Current Source
Driver Circuits
Filter Circuits
Fluid Level Monitor
Fluorescent Lamp Circuits
Freespace Communications
Frequency Divider Circuits
Frequency to Voltage Circuits
Hour Meters
Instruments
Lamp-Control Circuits
Latch Circuits
Laser Circuits
LED Circuits
Light-Beam Communications
Light Flashers
Lighting Circuits
Microphone Circuits
Motion Sensor
Multivibrator Circuits
Noise Generator Circuits
One Shot Circuits
Optical Circuits
Optical Filters
Opto-Couplers
Oscillators
Over-Temperature Circuits
Peak Detectors
Period to Voltage Converter
Photo-Flash Circuits
Piezoelectric Circuits
Pink Noise Generator Circuits
Power Control Circuits
Power Failure Alarms
Power Supplies
Pulse Generator
Push-Pull Circuits
Rectifier Circuits
Relay Circuits
Remote Control Circuits
RF Transmitters
RFID CircuitsSensors
Signal Generators
Solid State Relays
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Switch Circuits
Telephone Circuits
Television Circuits
Television/VCR Remotes
Temperature Alarms
Testers
Timers and Counters
Touch Switch Circuits
Transistor Circuits
Under Voltage Monitor
VCO Circuits
Video Circuits
Voltage Controlled Oscillators
Voltage Converters
Voltage Monitors
Voltage to Frequency Converters
Waveform Generators
White Noise Generator
Xenon Lamp Circuits
Zero Cross Dectectors
Alarme
de Temperatura de Baixíssimo Consumo - 11 KBUma simples bateria de litium de 3 volt fornece alimentação do circuito por vários anos. Ele gera um alerta sonoro quando a temperatura excede um certo ponto. Com algumas poucas mudanças o circuito pode ser configurado para monitorar temperaturas negativas. O circuito usa um termistor de baixo custo, porém, de alta precisão.
Sinalizador
de Sistema Ligado (POWER ON) - 20 KB
Este circuito produz um beep curto uma vez a cada minuto. Ele é alimentado diretamente da rede elétrica (110V) para lembrar que um dispositivo conectado à rede elétrica está ligado. Ele é simples o bastante para ser colocado em uma pequena caixa de plástico e pode ser aplicado ao uso com computadoes, impressoras, e equipamentos de teste que não devem ficar alimentados o tempo todo.
Sinalizador
de Perda de Alimentação - 40 KB
Em
muitos equipamentos médicos é importante para o operador
ser alertado de uma falta na rede elétrica que alimenta o equipamento.
O sinalizador é alimentado por uma bateria de 9V.
DOORKNOB
ALARM - 45 KBMany companies offer simple alarm devices for personal use in bedrooms or hotel rooms. A metal chain attached to a box holding the electronics is placed around the inside doorknob of a wood door. Anyone grabbing the knob from the outside is detected by the electrical capacitance change that occurs from the human hand contact between the knob and the box. Almost all of the commercial devices sold use a more expensive and power consuming radio frequency circuit approach to detect the capacitance change. But, a very inexpensive and micro power technique can also work. This circuit schematic should dramatically reduce the cost of the device and allows it to operate for many years from one set of batteries.
ANOTHER VERY
LOUD PIEZO ALARM BEEPER - 67 KBThis is yet another beeper circuit that really draws attention. It sweeps the drive frequency slightly to produce a very annoying sound. It uses a transformer to increase the drive voltage across the piezoelectric device to more than 200 volts peak to peak. It cranks out an ear splitting 120db when measured at 12 inches.
WATER SEEPAGE
ALARM - 57 KBThis simple circuit sounds a beeper when its electrodes detect water. It is powered by a single 1.5v N cell. A small 1.5v button battery will also work.
BROAD BAND
5MHz OPTICAL FIBER RECEIVER - 30 KBThis circuit is a simple broad band light detector that uses a very inexpensive IC and a PIN photodiode that is packaged for use with plastic optical fibers. It has a bandwidth from 1KHz to over 5MHz. It is great for experimenting with various modulated light sources.
FET INPUT
HIGH SPEED LIGHT DETECTOR - 69 KBThis circuit is yet another design that converts current from a PIN photo diode to a voltage. It has a bandwidth that extends beyond 50MHz.
BROAD BAND
2MHz OPTICAL FIBER RECEIVER - 31 KBIf you need more sensitivity than the above circuit this circuit provides about ten times more gain. It too is designed around an inexpensive plastic optical fiber detector.
BROAD BAND
50MHz OPTICAL FIBER RECEIVER VERSION A - 32 KBIf the above circuit it still too slow, you can try this circuit. What it lacks in sensitivity it makes up for in speed. The circuit attaches a plastic fiber optic PIN photodiode assembly to a small box containing a small 3v battery and a standard standard BNC plug. When the box is plugged into to the input of an oscilloscope with a 50 ohm termination resistor, it can detect light pulse frequencies beyond 100MHz.
C-MOS INVERTER
MAKES LOW POWER AMP - 95 KBWith the addition of one resistor and a capacitor, some common logic ICs can be transformed from digital to analog duties. This circuit outlines some the features to expect from different inverter ICs.
This circuit uses NPN darlington transistor to amplify the signal produced from short light flashes, as detected by a PIN photo diode. The circuit draws only about 330uA from a 6v battery.
This circuit is similar to number 121 but provides more gain and operates up to 40KHz. However it draws more power supply current.