Free electronic circuit design and schematic diagram
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 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 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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Below is a 2-station intercom using common 8R mini speakers. The “press-to-talk” switches should have a spring-return so the intercom can never be left ON. Power the speaker from a separate power supply is the secret to preventing instability (motor-boating) with a high gain circuit like this. An extra station (or two extra stations ) can be connected to this […]
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When audio is detected, the output is push-pull and consumes less than 3mA (with no signal) but drives the earpiece to a very loud level. It’s extremely difficult to set up because the whole circuit is DC coupled. Basically you don’t know where to start with the biasing. 8k2 between the emitter of the first transistor and 0v rail and […]
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It’s good to use CS3310 because CS330 is a complete stereo digital volume control designed specifically for audio systems. This device has features like 16 but serial interface that controls two independent, low distortion audio channels. An array of well-matched resistors and a low noise active output stage that is capable of driving a 600 Ohm load is included in […]
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This is simple circuit for Guitar Pre-Amplifier. This circuit has some advantages such as it will work under tough conditions, very simple and has high input impedance. This circuit will not load down electric guitars because of the high input impedance. This circuit can be used to amplify microphones. Here is the circuit:A 9-volt battery is typically used as power […]
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