Need help with Aphex Aural Exciter type B Schematic

[ljudsystem]

Found this at Experimentalists anonymous and I really wan't to breadboard it but there's a page missing. Anybody seen this before? It doesn't say anything about the power supply so I guess that's on page two?

So I need a +- supply voltage , right? How big would it have to be? I guess I need more than +- 4.5V...

[Rob Strand]

It's something like this:


The filter pot is a reverse log taper.

From what I can work out, the input stage on the original is set-up for line input.

It doesn't say anything about the power supply so I guess that's on page two?

I'm not sure.  The second sheet is marked "Display" .  The part of the schematic missing is only a clip detector with two LEDs. One for + and one for - clipping.  The power supply isn't marked.  The other models seem to use +/-15V.

[Mark Hammer]

This should help.

[Rob Strand]

This should help.

On the right hand side you can see a dot near the 1k which is probably where the "page 2" part of the circuit connected.  [Actually that's a test point.  The other side of the 1k is the part that goes to "page 2" you can see a cut-off wire at the output of the opamp.]

That one shows the original input scheme.

[ljudsystem]

  Thanks guys, this is awesome.

So... for +-15 v I need 30v and a voltage divider network, right?

[StephenGiles]

Page 2 possibly had the power supply. I have an original service manual somewhere from the days of writing letters for circuits and I actually visited the UK agents for Aphex back in the 1980s. After spinning them a yarn, they gave me the service manual!!

I'll have a search over the Easter break.

[Rob Strand]

So... for +-15 v I need 30v and a voltage divider network, right?

It is pretty normal for things that aren't pedals to run from separate -15V / 0V / +15V supply.  Like a preamp power supply from guitar amplifier.

For example, something like this,  (I can't vouch for the actual circuit.)
https://i0.wp.com/powersupply33.com/wp-content/uploads/2017/03/15V-1A-Symmetrical-Power-Supply-Circuit-Schematic.jpg

You should be able to convert it to 30V and a Vref (+15V) but you might need to be careful about what goes to 0V and what goes to Vref.

[StephenGiles]

But it will work using 2 9v batteries, but not as long as a fuzz box.

[ljudsystem]

http://tagboardeffects.blogspot.se/2014/01/bipolar-voltage-converter.html

how about this instead?

[rankot]

Depends on load required by this circuit.

[StephenGiles]

I found various old scans that might be useful - first of all a clean circuit with no part values:

[StephenGiles]

Next is the circuit + part values:



Parts list:

[StephenGiles]

Circuit description 1:



Circuit description 2:

[StephenGiles]

Aphex B PCB:

[Rob Strand]

But it will work using 2 9v batteries, but not as long as a fuzz box.

Should work.  Maybe tweak R128.

http://tagboardeffects.blogspot.se/2014/01/bipolar-voltage-converter.html
how about this instead?

There's many options  but they aren't all *exactly* the same.

Another option is to target a +9V/0V/-9V set-up:
+9V battery --->  +V supply
0V battery    ---> 0V  supply
+9V battery ---> LT1054 negative rail --->  -9V

If you use good caps and large values on the input and output it should operate OK.

[Rob Strand]

This should help.

Mark, FYI, R123 should be 51k on your schematic.

[StephenGiles]

You don't want to overload this unit, because it will sound awful!

[ljudsystem]

Thanks for all the info guys.

Think I'm gonna try the two 9V battery trick first and see if I can get it to work.