VU Meter with Peak Detection

benny_profane

Well-known member
I really enjoy building utility circuits: signal routers, mixers, patch boxes, etc.—anything that can open up different options without changing fundamental elements or introducing anything new.

Even though their real utility is debatable and there are many other (better) line monitors, analogue needle VU meters have always been interesting to me. The addition of the peak detection circuit makes this more versatile and helps give a quick visual indication of transient spikes to avoid nasty clipping with my headphone amp.

I found a cheap DC meter on ebay and worked from the schematic in Figure 9 here. The SENSITIVITY control is a panel control; CALIBRATION is a trimmer. The meter didn't have a backlight, so I made a small LED daughterboard, filed out some notches, and secured it to the meter housing. It's set it so that the backlight is on when the circuit is active.

VU Meter (Circuit).jpg

VU Meter (Top).jpg

VU Meter (Angle).jpg

VU Meter (Backlight).jpg
 
Last edited:

benny_profane

Well-known member
The vero layout is attached. The 1k2 resistor is the CLR for the peak indicator LED and can be adjusted to taste. The 470nF cap determines how long the peak LED stays lit after the peak is detected and can be adjusted (I used a 1uF cap). See the notes for Figure 9 for more information.

For the standing 1n4148 diode, the anode is connected to TL072 pin 1 and the cathode is connected to TL072 pin 2.
 

Attachments

  • VU Meter with Peak Detection (Vero).pdf
    541.4 KB · Views: 9
Top