Free electronic circuit design and schematic diagram
This is a setpoint controller circuit using The AD596/AD597. The thermocouple voltage is amplified, compared to an external setpoint voltage, and cold junction compensated. The device temperature can be monitored if the temperature to be controlled is within the operating range (–55°C to +125°C) of the device. Here is the schematic diagram of the circuit: Setpoint Voltage of AD597 is […]
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This is a stand alone temperature transducer/sensor circuit. This device uses The AD596/AD597, employing its internal junction compensation temperature sensor inside. This device can be used as temperature sensor by omitting the thermocouple and connecting the inputs (Pins 1 and 2) to common. Here is the schematic diagram of the circuit: The output will reflect the compensation voltage and the […]
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This is a hearing aid circuit with 1.5v supply. This circuit is used to detect very faint sounds, then deliver the sounds to an 8 ohm earpiece. This circuit requires 1.5v input voltage, need only a single cell battery. Here is the schematic diagram of the circuit: This circuit can be assembled in a small board, or you can even […]
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This schematic diagram is about touch switch circuit. Separate ON and OFF switch improves the ergonomics for safety, since the touching off button when the state is off doesn’t make the system acts in the opposite way: turning ON the system. This accident usually happens when we make wrong assumption of the current state about ON or OFF of the […]
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This is a light alarm circuit. This circuit uses Light dependent resistor (LDR). When there is no light fall on the LDR, the transistor driving the speaker is not turned on, because its resistance is high. When the LDR receives light, its resistance decreases and the collector of the second transistor falls. The first transistor turn off slightly, via the […]
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This is a signal injector circuit. Signal injector is important tool for troubleshooting your electronic circuits. As an example, this circuit can be used to test amplifier circuit. Here is the schematic diagram of the circuit: This circuit also a lot of harmonics. By connecting the ground clip to the 0v rail and move through each stage, starting at the […]
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This is a microphone pre-amplifier circuit that use discrete components. The gain of this circuit is 100 and should be enough for most microphones. It is set by the ratio of the 10k resistor to the 100R. As common-emitter amplifiers, This circuit uses two directly coupled transistors. Here is the schematic diagram of circuit: Please note that this circuit has […]
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