Pro Audio Design Forum

I'm reintroducing, after a long absence, a 20 segment LED gain reduction meter for the Waveulator and compressor projects.





The actual board size is 3.1" by 1.0". The mounting holes are spaced 2.3".

The new version of the GR20 has bar/dot capability and more powering options.

In a recent Waveulator build I used the 5V output of the TDK CUT-35 5FF switcher to power the GR20 and it worked out very well relieving the bipolar supply - and it's ground - from meter currents which, at 10 mA/segment, is about 200 mA FS.

The full scale input voltage is 2.4V.

I should have a small run of boards this afternoon to test.

The boards run great and I have just a few at the moment.

Now that I know they run I'll order more...




GR20 Gain Reduction Bargraph. Actual size is 1.0" x 3.1"

The dot mode draws only about 20 mA; bargraph full scale about 220 mA.

The dot mode with the LTA-1000E displays has a slight minute glow at segment 1 (at the right-hand) and segment 11 (just past the middle) when those values are exceeded. This is a common LM3914 effect and although it can be resolved with two added resistors I chose to leave it because it provides a marker at 0 scale and mid scale. In a dark room, where you can't see the panel cutout, it provides a scale. One could actually ad resistors to brighten it as well.

Bargraph, which I prefer, doesn't exhibit this effect.

I put the bar/dot jumpers on the underside in this one so I could easily change it.

I'll need to fine-tune the spacer height to accommodate panel thickness but the 3/8" are pretty close. Front Panel Express can also do blind fasteners to eliminate exposed front panel mounting screws.

Cool.