These are basic measuring circuits you can build for your home lab.
I have documented a lab DMM i had built for my use many years ago. the circuits may have errors, build it only if you understand.
- DMM or digital multi meter
- LM3914 analog display
- 3-1/2 digital display
- Power supply with battery
- DMM range and AC-DC mode
- AC conversion continuity
- Voltage attenuator amp
- Current Shunt Amplifier
- Resistance Current Source
- Analog Buffer and Inverter
Analog Dial AVO Amps-Volts-Ohms meter
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 designed it to practice on eagle, 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 :~) - Low cost Dial AVO meter
Auto ranging 4-1/2 digit digital voltmeter using ICL7135 of Intersil.