6 LED voltage indicator circuits
This is four circuits of LED voltage indicator are simple and easy to builds for check voltage battery and others, use as zener,transistor,LM339 and more
Meters & Detectors
Include: Volt meters :: Sound level meter :: Analog vu meter :: Soil moisture meter :: Digital meter circuit diagram :: Temperature measurements :: Electronic measurement tools :: Frequency meters :: Best battery tester :: Transistor tester project
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Battery voltage monitor circuit by LM339
The simple low voltage tester circuit using LM339,can use Battery voltage monitor for voltage sources that problems, by LED display and alarm sound.
6 ranges AC millivoltmeter circuit
Sometimes, we need to measure a too tiny AC voltage level. And high frequency too. Ohh… We cannot use general multimeter. I recommend you try watching the AC millivoltmeter circuit. It includes the 6 ranges. Lowest is 15mV only. Also, it uses an analog meter form. So, you can watch easily a slow changing of … Read more
Simple Signal injector circuits using transistors
This is simple signal injector circuit, used two transistors join together as astable multivibrator, signal output frequency 1,000Hz in square wave form.[…]
Simple Refrigerator/fridge Door Alarm circuit
This is a Simple Refrigerator Door Alarm circuit, it will detect light of lamp in the fridge and alert with buzzer.Small size, easy to make and cheapest. […]