Free Circuit Diagram

LED flasher circuit here will flash a LED using only 1.5 volts  supply voltage. Normally, to make any LED lamp works, you need more than 2 volts power supply. This because LED will work only when the supply voltage is higher than its forward bias voltage, around 2 volts  for red LED, and slightly lower [...]

Classic LED Flasher Circuit This LED flasher circuit is a classic two transistor flip flop. This flasher circuit is very popular and it’s usually the first circuit to build when starting electronic circuit building hobby. Here is the schematic diagram of the famous LED flasher circuit: How LED Flasher Circuit Works [...]

For anyone who love transistor circuits, here you can find small wattage discrete amplifier. Building discrete amplifier is much more fun and some people say it’s involve more artworks than building the ones with integrated circuit. Look at the figure below for the circuit’s schematic diagram. A variable resistor 470 Ohm is provided [...]

This LED flasher give similar circuit with the previous transistor LED flasher, but this circuit use a 555  integrated circuit chip as the active component. Here is the schematic diagram of the LED flasher circuit: This circuit gives alternating LED flashing, but with different flashing period between LED 1 and LED 2. The [...]

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 [...]

Notch filter is known as band-cut filter or band-reject filter. The fuction of this filter is to remove some frequency portion of a signal. The schematic diagram of this filter circuit, a second order notch filter is depicted in the figure below. The formula is actually complicated, but by taking the R3=R4 and [...]