Hi
can someone tell me how to use an analog umeter to read dB - I am sure it can be done , maybe w/ some opamps or some passive components...!?
Any schematic(s) would be nice
THANKS
- Pierino
An analog VU meter is simply an AC voltmeter with a dB scale painted on it.
Do you need something fancier than that?
Example: h**p://www.sifam.com/vuppm.lasso
Thank you for your reply
What I want to make is to be able to read dB on a microvolt (or mV) meter . I will then make a new scale for the meter, but the point is to interface somehow the voltmeter to read dB. Maybe I need a log opamp amplifier .. or something similar !?
Thanks
You can convert your AC signal to DC and then feed it into a logarithmic converter circuit. Try searching National Semiconductor web site for application notes containing keywords such as log, logarithmic, converter, generator, amplifier.
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Here are a few examples:
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Here are some suggestions if your intention is to construct a true "VU" meter:
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The meter must repond to average, not peak.
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Ballistics are important. The meter must have a response time of about 300 milliseconds.
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VU meters are not necessarily linear in db, but if this is what you want, you must use some kind of Log converter, as Echo47 suggests.
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Regards,
Kral