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 [...]

For you who has failed to build  radio transmitters, this circuit worth a try. This circuit uses 74HC14 hex Schmidt trigger as the oscillator, and you can choose to use capacitor for low cost goal or quartz  crystal for better stability. For quartz crystal, you can choose any frequency between 00.7-1.6MHz, but around 1.6MHz is [...]

The frequency formula of 555 oscillator is popularly known. For a known resistors and capacitor, the frequency can be determined by a formula. From the math logic, if the frequency and the resistors are known, then an unknown capacitor could be determined by the inverse of the formula. Anyone who has a frequency counter are [...]

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 simple Batteries charger circuit is designed for NiMH/NiCd batteries. It need no micro-controller nor any programming. Linear Technology Corporation produce the LTC4060, an autonomous 1- to 4-cell, 0.4A to 2A linear NiMH and NiCd battery charger complete controller. Here are the main features: No Sense Resistor or Blocking Diode [...]

It seems that center tapped transformer with a bridge diode is common solution to provide symmetric supply, but we can actually do it with simpler solution, using a voltage doubler – rectifier diodes. You can see this simple circuit in the figure. The capacitor need to be large because the rectifying is half [...]