Free electronic circuit design and schematic diagram
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 […]
Read more
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 […]
Read more
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 […]
Read more
This is a circuit that can produce 6 million gain. As well as detecting general electric noise, this circuit can be used to detect “mains hum,” the presence of your hand without any direct contact, and detect static electricity. Here is the schematic diagram of the circuit: The mains cable can be located by this circuit by moving it across […]
Read more
This is simple logic probe circuit. Logic probe is used to determine if a point in a circuit has high or low state when the circuit is in operation. Here is the schematic diagram of the circuit: When the probe is not touching any circuitry, this circuit consumes no current. It can happen because the voltage across the red LED […]
Read more
This is Discrete Running LEDs circuit. This circuit gives a chasing pattern like the running LEDs display in video shops. Here is the schematic diagram of the circuit: When the power is applied to this circuit, all transistors will try to come on at the same time. However, some will get a different turn-on current because of the exact value […]
Read more
The load inrush current is limited by the TPS2331. The system also protected by TPS2331 from a load fault in its traditional tole as a hot-swap controller. However, the TPS231 must protect the system against a power supply module fault in an OR-ing circuit. The TPS2331 is required by the former role to trip if excessive current flows into the […]
Read more