Free Simple Circuit Diagram
This is Single-Supply Current Monitor circuit. Amplifying the voltage drop across a resistor placed in a series with the current to be measured is the essential of current monitoring. However it is difficult because with low precision op amps this greatly limits the overall resolution and only small voltage drops can be tolerated. Here is the schematic diagram of Single-Supply […]
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This is infrared (IR) proximity detector circuit. A matched infrared emitter and detector pair is used in this circuit. The voltage controlled oscillator section of the LM567 tone detector IC is used to set the emitter LED pulses at frequency. In this circuit, the center frequency of the VCO is set to about 909 Hz by combination of capacitor C1 […]
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The output of this circuit will be activated when a mix of two tone/frequency is detected on the input. The frequency f is determined by the values of R1 and C1, where f=1/(1.1 * R1 * C1). For security, using dual tone is more secure compared with using only single frequency. With single frequency, someone can easily find the secret […]
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Using 567 IC tone decoder/detector, we can build a remote control and or intercom. This circuit can be used to control a relay, or to carry an audio signal (intercom) through power-line wiring. Here is the schematic diagram of this remote control/intercom circuit: The relay will be activated if you inject a 100kHz tone. This can be used to control […]
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