See LED VU meter using transistor is analog circuit to show the level of power audio signal. You can build 5 LED to 20 LED display with PCB.
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
SEE a simple salinometer or salinity tester in food and water. Good for health. Using LM324 and few parts and LED display easily use, with 9V batts
his is Digital multimeter circuit using ICL7107. dc digital meter circuit to smart full function, measure DCV, ACV, DC Amp meter, AC Amp meter, Ohms [...]
These are four light sensor alarm circuits, when be become dark, or Light sensitive switch.Use part is important light sensor LDR light dependent resistor [...]
Here is simple ICL7017 digital voltmeter circuit easy to build and cheap because it is high technology, by single IC,small number, along by LED 3 digit.