- on Test & Measurement
- Published in issue 7/2008 on page 46
Solar Cell Voltage Indicator
This device is designed to be a simple, inexpensive 'comparator', intended for use in a solar cell power supply setup where a quick ‘too low’ or ‘just right’ voltage indicator is needed. The circuit consists only of one 5-V regulator, two transistors, two LEDs, five resistors, two capacitors, and one small battery.