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Log voltmeter


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Many years ago I've seen an application of a converter IC (ICL7106 style) displaying a dB output without any explicit log converter.
The circuit was based on a special connection of the input, reference and integrating pins, but I do'nt quite remember how it worked or where it was published.
Does anybody have details about such a circuit?

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  • 2 weeks later...

A simple op-amp with a NPN transistor and small switching diode in the feedback loop makes a logarithmic amplifier. You also need a small cap there to keep the circuit from going into oscillation.

It is called a transdiode logarithmic amplifier. Try this in your word search and you should find the information you are looking for.


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