small Metronome using 2N3904

http://www.elecfree.com/electronic/small-metronome-using-2n3904/

Infrared Intruder Alarm

This the circuit warns the trespasser infrared system or Infrared Intruder Alarm circuit that interesting. By when there is a person passes or cut the light infrared.


http://www.elecfree.com/electronic/infrared-intruder-alarm/

Two Tone Alarm with IC LM3900

http://www.elecfree.com/electronic/two-tone-alarm-with-ic-lm3900/

Low pass filter circuit 10KHz using uA741

http://www.elecfree.com/electronic/low-pass-filter-circuit-10khz-using-ua741/

Small IC Amplifier 2 watt using LM380 | Circuit Project Electronic

Small IC Amplifier 2 watt using LM380 | Circuit Project Electronic

Compares with sound level tool | Circuit Project Electronic

Compares with sound level tool | Circuit Project Electronic

Low impedance mini amplifier | Circuit Project Electronic

Low impedance mini amplifier Circuit
This circuit can apply to signal sound source that has low impedance , such as from 4-16 ohm size loudspeakers or telephone earphone that use to replace