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Incorporating a PanelPilotACE into the Red Tin Part One: A VU Meter with Envelope Follower Circuit

Dave Ives
3
I currently look after production at AB Open. I have a background in the arts, environmental conservation and IT support. In my spare time I do a bit of DJing and I like making things.

Comments

November 17, 2020 10:38

Hi Dave: I'm going to give the PanelPilot a try. Did you connect the circuit to TBLK1 or PL11? Also, from the photo it does not appear that 0V was connected from the circuit. Correct?
Thanks, Tim

0 Votes

July 23, 2019 08:49

Hi; I understand the motivation for showcasing the particular display utilized in this project but adding a ~270€ programmable touch screen display for this particular application (and implementation) seems a bit of an overkill... also; if using such a powerful display, wouldn't a MCU-based envelope estimator have made more sense?

July 23, 2019 07:16

Hello Dave. I hope you don’t mind a few comments on this circuit, but there are several things wrong with it.
The NE5532 is not designed to work from a single 5V supply. The data sheet shows a minimum of +/-5V (10V overall). It has a typical maximum output of 2V below Vcc – i.e. 3V in this case. Even with no signal, given the 0.5V or so drop across the diode, the output will already be nearly at maximum, which means that it will go into saturation with very little signal applied – i.e. the circuit will not be operating in the linear region as intended/required.
The A:D converter will be operating over a very small range, which is the opposite of what you need because the software needs to perform a logarithmic conversion to scale to VU units (it is not clear whether the VU driver actually does this conversion, but I suspect not).
I have not tried the circuit myself, but if you hook the input up to a signal generator and check the meter reading I would expect a very poor correlation between it and what it should be reading for a given input signal. Essentially, you would have a very nice display, let down by the front end.
There are other issues, but these are the major ones.
Kind Regards, Graham Booth BEng CEng MIET

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