Free Circuit Diagram

In some PLL application, sometimes we need to provide lock indication when the PLL is in locked state. The simplest one is binary indication, 0 or 1 to correspond with lock/unlock condition. This  condition should be easy to be presented with a LED lamp. The schematic diagram  shows a lock-detection scheme [...]

The circuit below is a schematic diagram of a fast pulse detector. At 100 ns  or wider pulse width, the detection should be error free. At 60 ns pulse width,  the detection error should be under 10%. This circuit should be used to detect at least 100 ns wide pulse to ensure an [...]

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: [...]

Pulse position modulator can be easily built using 555 IC. Here is the schematic diagram of the circuit: Pulse position modulator modulate the on-period while keeping the fixed off-period. Pulse position modulation might substitute pulse-width modulation in some application. The main difference between pulse position modulation (PPM)  and pulse width modulation (PWM)  is [...]

Electrolysis process has been the primary cause of your water level detector probes, and you can avoid this by sensing the current by this probe using alternating current. In alternating current, the electrolysis process will be reversed for every alternating cycles, making the probe will last longer to survive from corrosion. The electronic circuit for [...]

Tired replacing your power supply fuses, or it cost too much because too often to blow? Use this electronic fuse and your life would be easier. It is good for your new power supply design, or you can just add it to your old power supply unit. This fuse has real fast response because it [...]