vu meter circuit


Posted on Feb 5, 2014

This is by far the simplest VUmeter you can build. It is based on a single chip. A volume unit (VU) meter or standard volume indicator is a device for displaying the level of any voltage signal source (which is usually a sound signal). Connect the module to the output of any amplifier (or preamplifier) and set the trimmer where all LEDs are lighti


vu meter circuit
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ng, when the volume of the amp is at maximum (or at least at that point, where you want all LEDs to light). LM3915 is a very powerful and easy to find chip. It`s a monolithic integrated circuit that senses analog voltage levels providing a logarithmic 3 dB/step analog display. With it, you can drive LEDs, LCDs or even VFDs (Vacuum Fluorescent Displays). In this circuit we use it as a VUmeter, driving 10 LEDs. Each time a new LED is lighting when the input voltage is 1. 41 times the voltage, where the previous LED started to light. This is exactly the point where the voltage is 3dB higher than the previous one. Also you will need a stabilized 12V external power supply. You can power the VUmeter directly from the power source of the amplifier (or preamp) providing the input signal (meaning if the amp is also using a 12V supply). Attention: Make sure you solder the 100nF capacitor as close to LM3915 power supply pins as possible. The optional electrolytic capacitor is required only if leads to the LED supply are 15cm (about 6 inches) or longer. All 220 © resistors are used to limit LM3915 power dissipation and aren`t optional.




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