Free Circuit Diagram

Metronome is very important tool if you studying music playing. There are mechanical metronome device in the past, but today, electronic metronome is much more popular since it can be very simple, compact/small, reliable, and also has the most interesting feature: cheap. Here is one example of the electronic metronome schematic: Parts: [...]

This transistor tester is very helpful if you need to sort bulk transistors. In  some market, if you know where to find it, sometimes you can get transistors sold in kg unit, not in single peaces unit. You can buy 1 kg of transistors with really cheap prices. Don’t be too happy right now because [...]

It would be cool and elegant to a have mechanical sound character for our electronic metronome. This electronic metronome circuit will produce such sound, making your life more fun. Here is schematic diagram of the circuit: The metronome circuit consists of two 555 oscillators. The first oscillator is used to make high frequency [...]

Although this circuit use more resistor components than in basic standard three op-amps instrumentation amplifier circuit, this circuit has the benefit of easy gain adjustment with only one control resistor. Because the easy gain adjustment feature, this circuit topology has been used inside a single chip instrumentation amplifier ic. The figure below shows the schematic [...]

In designing small signal amplifier circuits, to achieve a specified amplifier gain we usually use opamp amplifier design to ease the setting of the gain. When the gain accuracy is not critical, we can use transistor feedback amplifier as the base of our amplifier design. Here is the schematic diagram of the transistor amplifier: [...]

The function of this circuit is similar with the hum filter in our previous circuit, but it use transistors instead of op-amps. It uses BC109 transistors, but any low noise high gain type will be suitable. This hum filter is adjustable via trimmer pots to fine tune it’s notch depth.   The figure below shows [...]