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MSGEQ7 without micro controller?
MSGEQ7 without micro controller?
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Old 15th October 2012, 08:39 AM   #1
theb0b is offline theb0b
diyAudio Member
Join Date: Jun 2012
Default MSGEQ7 without micro controller?

There seems to be a lot of projects using Arduino and the MSGEQ7 chip, but what about using logic circuits?

As far as I can work out the MSGEQ7 outputs a multiplexed DC signal referencing VCC, (which is 5V) for each of its 7 channels. So...

Can I just sling this signal into a 4017 decade counter, give both the chips a timing signal from a 555, and output directly into 7 LM3915's to drive "daz blinken lights"?

Am I going to need to buffer the output into/out of the 4017?

Is there anything I've missed?

I'm trying to avoid all of the programing malarkey, and doing it old school.

I'm wanting 7x10 or more LED's for each channel.
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Old 15th October 2012, 03:08 PM   #2
Simon B is offline Simon B  United Kingdom
diyAudio Member
Join Date: Dec 2011
Location: North-East England
Feed the 4017 from your clock, using glue logic to have that reset after count 7

Output from the MSGEQ7 is time division multiplexed analogue, so you need to separate the 7 outputs with 7 sample and hold circuits, one for each driver chip, enabled by the count from the 4017.

Signal input to the LM3915 on pin 5 is high impedance, so your sample and hold circuits may need to be just a fet, a diode and a capacitor.

Alternatively, you could ditch the 4017 and do the count in binary, then use a HEF4051B (de)multiplexer, with a small cap to ground on each output, feeding the LM3915s

Don't forget that you need to provide a reset pulse as well as the strobe.
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Old 15th March 2013, 01:01 PM   #3
Wezly is offline Wezly
diyAudio Member
Join Date: Mar 2013
Look at the block diagram from the data sheet; you'd be better just using opamps and skipping the multiplexing at the end.

I bought these and had the same lack of interest using a micro controller, but that's really what they're for. Otherwise, you're just making redundant peak detectors.

Try taking the filter section out of this:

Nixie Music Visualizer | tchips.com
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