This is First stereo tone control board for a electronic students, so small,easy to build all in one PCB ,cheap. use transistors, few parts so low noise
The peak hold vu meter circuit on 12 LEDs stereo system and use L1424 as main so easy to build with PCB layout to peak voltage detector
High performance LM3914/LM3915 VU meter circuit projects that widely popular can display with 20 LEDs on stereo or mono with 10 LEDs for all audio system.
The digital clock circuit board using LM8365,alarm and relay control, alert 2 times in 24 hour,backup battery power outage. Show dates, months or seconds
This is daylight sensor switch circuit, for control load turn on when have sunlight. use simple circuit LDR,transistor,relay and can use with 12V supply