A portable and compact voltmeter is often nedeed but the usual multimeters are bulky, impractical and heavy (for portable use).
Therefore, I made a little voltmeter, which shows the SLA battery voltage via a blinking LED.
I made it around a PIC 16F876A microcontroller using the embedded ADC.
All can be made on a perfoboard as a Do It Yourself (DiY) Project for a raini afternoon.
Here is the schematic diagram (CLICK to enlarge):
The LED shows the following voltages;
|LED 1||< 11 V||Bright RED|
|LED 2||11 V - 12 V||RED|
|LED 3||12 V - 12,4 V||YELLOW|
|LED 4||12,4 V - 12,6 V||GREEN|
|LED 5||12,6 V - 13 V||GREEN|
|LED 6||13 V - 13,3 V||GREEN|
|LED 7||13,3 V - 13,8 V||YELLOW|
|LED 8||>13,8 V||Bright RED|
Al the nedeed files are .rar archived and available for download HERE.
Here is a little movie with the voltmeter:
If you found this usefull, please drop a line!
73 de YO3HJV
A explanatory article was published into the QRP Quarterly (Spring 2012)
Here is another link to download QRP Quarterly with SLA PIC Voltmeter.