3
\$\begingroup\$

I have found this circuit of a millivoltmeter, and it seems like something which as a hobbyist I can do it, and the range of the measurement is very suiting one of my projects, but I would like to attach it to an Arduino interfaced precise 24 bit ADC, so my question is:

  • How to replace the ammeter with a voltmeter in order to interface an ADC?
  • Is there some better replacement of the IC LF351 in the same circuit?
  • What diodes I shall use as the best option?

enter image description here

\$\endgroup\$
6
  • 5
    \$\begingroup\$ Um, that circuit is so old that the diodes used aren't even produced anymore; and the opamp used is also positively ancient. Modern self-compensating opamps can do this with far less error and less complex circuitry. This circuit is a non-start. It wasn't even a good way to start a measurement device when it was designed: diodes are among the least consistent and most temperature-dependent devices that exist, and you'd very much avoid using them without a closed loop in a measurement circuit. This, again, shows the age of the circuit: today, opamps are cheaper, so precision rectifiers exist. \$\endgroup\$ Commented Jan 5, 2020 at 13:25
  • 1
    \$\begingroup\$ So, maybe you want to edit your question and explain what you want to measure for what purpose – I think you'll get some helpful recommendations out of that; aside from "don't do what's depicted there". \$\endgroup\$ Commented Jan 5, 2020 at 13:28
  • 1
    \$\begingroup\$ The circuit is also not suitable because neither end of the meter movement is connected to ground. This would be a requirement for feeding into a microcontroller's analog input. \$\endgroup\$ Commented Jan 5, 2020 at 13:35
  • 3
    \$\begingroup\$ Also, assuming your last "question" (you forgot to ask anything in there!) is related to this: Why did you suddenly go from measuring nanovolts (which is hard) to millivolts (which is quite literally a million times easier)? I think it's impossible to help you until you tell us what you want to do, in the bigger picture – this is the classical XY Problem, so I'm voting to close your question as unclear until you define what you want to achieve, overall \$\endgroup\$ Commented Jan 5, 2020 at 13:36
  • \$\begingroup\$ Hey Marcus ! Thank You for the great points ! I am a bit disappointing to be honest that these things went not as I believed it will, but that's the life I presume. Well.. generally I have a few things in mind, but mostly experiments as a hobbyist and learner. I would really love to do something really working from the part of measuring at last in the millivolt range AC voltage with Arduino alikes. \$\endgroup\$ Commented Jan 8, 2020 at 22:26

0

Reset to default

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.