Analog Dial AVO Amps-Volts-Ohms meter - del00023
This is a Amps Volts and Ohm Meter without a
Display. It has a Potentiometer that has to be
turned to make a measurement by watching the Bridge
Balance LEDs switch ON state.
The real reason of doing this is to help students
understand the various sections of parametric
measurements. By building this you will learn more
about analog design and instrumentation.
This was designed, keeping in mind, that sometimes
we have few components available and we could be
flat broke. Even that you could not carry your DMM
somewhere, but you have to make some instrument for
a quick need with what is available. If you are out
of cash or feel like Robinson Crusoe, then this is a
low cost measurement system. I am not sure how this
circuit may work, it is not tested . But i have
built, repaired and designed many DMMs. So there is
a fair chance, parts of it may work :~)
AVO Amps-Volts-Ohms meter - del00023
view circuit. Click the Link of PNG or PDF and view
the Circuit, PNG can be Scrolled with Mouse.
IC3 LM555 is to generate -5V from 9V. In those
days small firms used to make DPM's digital panel
meters with 7107. In 1987 when i got a
oppurtunity to design a DPM for a firm, I put the
555 clock in place CD4009 clock shown in intersil,
to derive the -5 (-3V).
This circuit is battery operated and has easily
available LM324 quad Opamp and Timer LM555. Some
Small signal Transistors and Diodes. Resistors and
Caps. Yet it is difficult to build and make it work.
You can even integrate a Digital or Analog meter
after you learn and gain expertize.
In those days other databooks i referred were from,
TI, SGS and Fairchild. So most of these
ideas with which i design opmaps were learning
that came from their application notes and
datasheets. So read them and then you can understand
The Source File in Cadsoft Eagle - del00023.zip.
Potentiometer Dial GIF for above circuit to be used
to make a hand-held avo-meter.