This is an audio level meter hobby circuit using LM3915 sound level IC that works great on supply range between 3V to 20V . This can be used in audio amplifiers however nowadays trend is using digital equalizer. This circuit is designed to give input voltage 1V(p-p) and a maximum input voltage of 1.4v.
It uses 10 standard LED's for displaying the level of single channel and if you need two channels, then construct two identical circuits. This can be cofigure to show moving bar or dot display by connecting or disconnecting the pin no.9 from +V. The circuit diagram and component list is given below.
Component list
Parts Description
- R1, R3 1K 1/4W Resistor
- R2 10K 1/4W Resistor
- R4 100K 1/4W Resistor
- R5 1M 1/4W Resistor
- C1 2.2uF 25V Electrolytic Capacitor
- C2, C3 0.1uF Ceramic Disc Capacitor
- D1 1N914 Silicon Diode
- Q1 2N3906 PNP Transistor
- LED1-10 Standard LED
- U1 LM3915 Audio Level IC
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3 comments:
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Hi
I've seen this circuit used as an audio watt meter. In the watt meter circuit, you have to adjust R1 based on the amplifier impedance.
Is ther a way to modify the circuit so it auto adjusts for 2,4,or 8 ohm amplifier impedances?
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