voltage display


New Member
Guys what will i need to make a digital voltage display measuring from 0-15v??

Any ideas on a circuit??


Two resistors for potential divider (15v to 5v), 08M, readadc command.
Power 08M via 7805 voltage regulator (plus associated input/output/decoupling caps).
Display, depends on what you want to show.
AXE033 driven with serout is easiest. 1 pin.
3 X 7 segment display driven by 4026 counters very easy.

Wasn't this exact question asked a few days ago?
GCSE coursework by any chance?


Technical Support
Staff member
A potential divider which converts 15V to 5V fed into a PICAXE ADC input, an accurate 5V supply rail, a means of display, and a few line sof PICAXE code. So that's two resistors, a PICAXE and an AXE033 serial LCD module for the most basic PICAXE solution.

For more accurate readings you'll need an accurate or adjustable potential divider and/or an accurate power supply or a reference voltage to allow PICAXE software to compensate for any inaccuracies and fluctuations.

Depending upon the voltage source you may need to buffer the input volatge through an op-amp and that can add complexity if you need to go down to 0V or up to 15V.

You could of course just buy a digital panel meter which would probably only need a power supply plus single resistor to configure and calibrate.


New Member
it isnt for GCSE no, it is for measuring the voltage of my second car battery in the boot!! Can anyone explain in laymans terms what the above means?


Senior Member
Just buy a cheapie DMM- these sell here in NZ for just ~US$3-5! However the open circuit voltage of a lead acid battery is additionally not a valid measure of the energy within! Older ones develop high internal resistance & no longer supply decent currents. You have to test under load normally.