Audio Level Meter
Circuit : Andy Collinson
Email: anc@mitedu.freeserve.co.uk
Description:
Audio levels can be monitored using a
small panel meter with this circuit built from discrete components.
Notes:
The circuit has a flat frequency response
from about 20Hz to well over 50Khz. Input sensitivity is 100mV for a full scale
deflection on a 100uA meter. Built on two common emitter amplifiers, the first
stage has a preset resistor which may be adjusted for a FSD. The last stage is
biased to operate at roughly half the supply voltage for maximum ac voltage
swing. Audio frequencies are passed through the 10u dc blocking capacitor and
the full wave bridge rectifier converts the signal to a varying dc voltage. Note
that the meter reading is instantaneous and will not provide a "peak" reading. A
peak reading audio level meter is also available on this site click this
link.
