EQ / VU circuit for errors??

pic of only part of 10 band stereo EQ with 2 10x10 matrix vu displays
any errors etc?? before we finalize the pcb

I think the filter must feed its precision full wave peak detector then have the outputs of the peak detectors switched to the display driver.

You won't have a good signal to the peak detector nor to the output amplifier with the diode messing up the signal.

The 10k pot and 100k resistor at the output of the filter are a problem because the peak detector must be fed from a low impedance.

You are trying to use the filters for EQ and for the frequency display but I don't think it is possible. Usually one set of filters are for the EQ and another set of filters is for the display.

circuit misinturpeting?

the filter output (oups the 10K pot has one of its legs grounded) feeds the 4016 which then feeds the peak dector.Diode is before the peak detector feed?
perhaps insert 1/2 wave peak detors per filter? using transistor per data sheet?
low impedence to peak detector ? maybe I need to research this or insert an op amp for each filter??
This is the basic filter circuit I am using https://www.uashem.com/index.html?pa=printpage&pid=431
the display is based on the vellman circuit.
thanks for looking and I will make changes?
hope I don't need seperate circuits for display and stereo audio output

I think I found solution??

found a webpage dealing with peak detectors
https://ethanwiner.com/meters.html
pic of circuit attached.
maybe just insert the A1 circuit before the peak detector?

I wish you posted a block diagram of your project.
1) Do you have a filter, peak detector and LM3916 for each frequency band?
If you do then you don't need the CD4016 switch.
2) If you want to use a single LM3916 and multiplex all the frequencies through it then the LEDs will be very dim and many CD4016 switches must switch all the peak detectors one at a time to the input of the single LM3916.

The filter and the peak detector must be fed from the low output impedance of an opamp, not from a resistor and not from a pot.

block diagram of circuit +

the url has a block diagram of basic circuit
the attached thumbnail has 2 urls pasted into it for the buffer/peak dector and the display from the vellman circuit.
this circuit planning is kinda fun. learning all kinds of things.
Thanks for the excellent input advice

https://www.electro-tech-online.com/attachments/audio-spectrum-analyzer-en-pdf.15065/

I think the opamp feeding "audio out" is a mixer of all the filters, isn't it?
Then it has no signal where you have a diode feeding the CD4016 switch because the mixing input is a "virtual ground".
The signal is at the slider of the filter's level control.

Why is there a diode feeding nothing to the CD4016? A diode can't pass a signal without being biased "on".

You need to re-arrange the circuit so that each filter feeds its peak detector circuit. The output of each peak detector should have its own filter capacitor then the CD4016 switches can feed the level across each filter capacitor to the input of the LM3916.

But using a single LM3916 will make the LEDs extremely dim because each LED column is turned on only 1/10th of the total time by the multiplexing.
If each filter had its own peak detector and had its own LM3916 then the LEDs will be normal brightness.

Giving TINA a try-software

Trying out TINA a circuit simulator.
found that adding a cap and diode as pic I can get the led to light.
will add a peak detector circuit to each filter etc.
maybe we need more lm3916s? or??
the pic is one filter. Just need to figure out how to use the different meters etc.
young scout still wants to build a "pocket" vu/eq unit w/ 6 bands.
going to try using smd- are monthlic caps good or should we be looking at ceramic smd?

Now your circuit is just a bunch of random parts and lines.
Important parts are missing.

oups drew circuitwrong

here is a revised circuit but using TINA I havn't figured out how to get a frequency graph using the function generator and the siginal analizer.
I changed the circuit to correct connections etc. thanks for finding the errors.
I got the led to light but not sure if circuit will still EQ audio output
oups pic is jpeg hope you can still decipher.
this HOVERSNAP prg is great.

I still don't know what you are doing:
1) The input opamp doesn't have an input resistor.
2) The input opamp has a resistor to ground at its output that is not needed.
3) The input resistor to ground of the filter seems to have a value too high.
4) The filter has very high value capacitors for an extremely low frequency.
5) The filter has a 1m resistor (0.001 ohms) instead of 1M (1 million ohms).
6) The PNP transistor has nothing to turn it on. The diode and capacitor can drive the NPN emitter-follower LED driver directly instead.

audioguru said:

I still don't know what you are doing:
1) The input opamp doesn't have an input resistor.
2) The input opamp has a resistor to ground at its output that is not needed.
3) The input resistor to ground of the filter seems to have a value too high.
4) The filter has very high value capacitors for an extremely low frequency.
5) The filter has a 1m resistor (0.001 ohms) instead of 1M (1 million ohms).
6) The PNP transistor has nothing to turn it on. The diode and capacitor can drive the NPN emitter-follower LED driver directly instead.

Click to expand...

It just looks to be a random collection of components, with no idea of how they should be connected, or what values should be used?.

will recheck schematic

it is a combo of 2 seperate circuits.

MrDEB said:

it is a combo of 2 seperate circuits.

Click to expand...

No, it's a random collection of parts which can't possibly work, you can't just add two separate circuits together and throw half the parts away for some random reason. There's hardly anything correct on the entire diagram.