# Change ac volt meter to a dc volt meter

M

#### [email protected]

Jan 1, 1970
0
I have few ac volt meter 0 to 30 volt, and i would like to buld
a car battery charger, can i just use one diode series on the
conection to convert the ac volt meter? Can any person help. thanks!

R

#### redbelly

Jan 1, 1970
0
I have few ac volt meter 0 to 30 volt, and i would like to buld
a car battery charger, can i just use one diode series on the
conection to convert the ac volt meter?

No.

You will need to get a DC volt meter.

Mark

P

#### petrus bitbyter

Jan 1, 1970
0
I have few ac volt meter 0 to 30 volt, and i would like to buld
a car battery charger, can i just use one diode series on the
conection to convert the ac volt meter? Can any person help. thanks!

You can try to measure AC voltages using a DC meter this way. However, some
types of AC meters act on DC voltages as well. You can try out using a DV
voltage source and a series resistor - of let's say 10k - to stay on the
safe side.

petrus bitbyter

R

#### Roger Johansson

Jan 1, 1970
0
I have few ac volt meter 0 to 30 volt, and i would like to buld
a car battery charger, can i just use one diode series on the
conection to convert the ac volt meter? Can any person help. thanks!

The first you should do is open one of the AC voltmeters, find out what
components there are inside. Chances are great that you can use part of
the circuit for DC, with some simple change.
There may be a capacitor to isolate for DC, and in that case you can
simply bypass with a short piece of wire to get a DC voltmeter.

As somebody said, try using the meter for DC, it may work directly.
Check the calibration of the scale in this case.

A more complicated alternative is to build a chopper which transforms a
DC voltage into AC so it can be amplified with AC amplifiers and
measured by an AC voltmeter.

A chopper has a measuring input prope which is quickly switched between
ground and the point to be measured.

This creates an AC signal with an amplitude equal to the voltage
difference between ground and the point of measurement.

The switches can be electronic switches or relays.

After the chopper stage, and optional AC amplifiers, we put the

Chopping is a way to measure very small DC voltages. The created AC
voltage has exactly the same amplitude as the DC voltage. It is then
easy to amplify the AC voltage. We have decided the frequency ourselves
and it doesn't change, so we can use tuned amplifiers to amplify the
signal by a certain number of decibels, or by a certain amplification
factor.