LED as a Light Detector Circuit Circuit Diagram These are 8 Low Battery Voltage Alarm indicator circuits, as ideas to make small projects, they use LED display easy, cheap with normal parts look below
I want to design a circuit that has 3 LEDs connected to it. When the voltage of the power source connected to the circuit is 3.6 volts I want only the first LED to light. 7.2 volts I want the
Contact AC Voltage Detector using 2N3819 MOSFET Circuit Diagram
Description This circuit, designed on request, has proven to be useful to indicate when the voltage in a power supply line is changing from 120V to 240Vac. It can be used in different circumstances and circuits, mainly when an increase in ac or dc supply voltage needs to be detected. We have many ways to indicates an AC line. A good way, the AC mains voltage indicator circuit with a LED. It may be the best choice. It save and to be easy.
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
How to Build Voltage Level Indicator Circuit with a Zener Diode Circuit Diagram
The beeper circuit is built around this IC so when the IC activates it will blink the LED and the buzzer will start producing a beep beep sound, giving an indication of the detection. The time period of LED and buzzer activation is set by the values of the resistor and capacitor used at the input of 555 IC.
