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audioguru
Nobel Prize Winner
Canada
4218 Posts |
 Posted - Oct 05 2010 : 12:39:35 PM
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The input is the input and of course the input also needs to have a ground wire.
The peak detector transistor does not work properly. The datasheet for the LM3915 shows the same peak detector circuit but has its reference voltage set so that an input of 10V peak lights the 10th LED.
The reference voltage in this project is set at only 1.25V which causes a few lower LEDs to light all the time.
I made a sound level meter with an opamp as the peak detector. It works perfectly. The opamp is similar to the opamp circuit shown on the datasheet for the LM3915. |
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Input on Sound Level Meter ?
