This Retro-Style Analog Audio VU Meter Was Made From Scratch
The homemade device features gauges from an old Akai cassette player.
A few years ago, JT Makes It created a pretty cool-looking stereo analog VU meter, capable of plugging into a standard 3.5mm headphone jack or a line output. It also contains a pass-through jack that lets anyone connect an MP3 player or a phone in the back-end. Headphones can be plugged in the front of the analog VU meter. Regardless of the volume level, the sensitivity can be set via the adjustable gain. The adjustable backlight brightness makes it visible regardless of the ambient light intensity.
A dual gang logarithmic potentiometer is connected for audio gain. JT Makes It used the expensive P9A2R100FISX1103ML. Ideally, a reverse log audio potentiometer would be implemented since the normal version works backward. When it’s turned clockwise, it reduces the sensitivity. Small PCB multi-turn trimmers calibrate the channels, enabling both meters to display the same gain level at a set volume. The D11 PESD5V0L4UG protection diode is responsible for preventing static electricity from damaging the circuit when the connectors are inserted.
The whole device is powered by a 5V mini USB plug. JT Makes It used VU dials from a broken Akai cassette player, giving it a retro appearance. This is 500uA of current type, which supports the electronics in this gadget. The circuit detects the amplitude of peaks in the audio signal and converts it into a current that moves the analog VU dials.
The main gain knobs work backward. If they’re rotated clockwise, the sensitivity decreases. This is a neat feature because the knob is always turned as much as the volume knob on the VU meter. The gain is controlled via the front knob, allowing a user to set the maximum needle movement at any volume. Lastly, the potentiometer, which is located in the rear, handles the LED backlight brightness.