Help with 0-5V CV pedal needed

[4nkam]

Hey everyone, I am having some trouble building a CV pedal and hoping some of you might be able to help me out here. Here's my situation:

I currently have a Dunlop 1SR rackmounted wah. This is normally operated via 1-4 control pedals that look like normal wah pedals. They have a 100k audio pot, small circuit board, a normal crybaby stompswitch, and a single TRS cable which goes back to the rack unit. There is a built in feature on the rack which allows for Remote CV. When you press this button, it overrides the normal resistor based control pedal system.

Now, once you press the Remote button and it bypasses the normal control, you have to plug a CV pedal into the rear. This pedal should:

1) Connect via a TRS cable
2) provide 0-5V
3) contain a crybaby stompswitch to turn the effect on/off
4) contain a 9v battery
5) use a 6 pin female TRS jack

I spoke with one of the main engineers at dunlop yesterday and he gave me a lot of good starting information, but I need to figure the rest out and he isnt working today. Here's how I currently have it set up:

-9v battery (outputting a little over 6v) connected to the outer terminals of my 100k pot.
-battery negative/pot connected to TRS jack Sleeve
-battery positive/pot connected to one terminal of my switch,other switch terminal connected to a 2k resistor in series to the TRS jack Ring
-pot wiper/(0-5V output) to TRS jack Tip

With that setup, I can get the effect to turn on/off but it will not WAH, will not respond to the change in voltage.

Any ideas?

[Gurner]

I see no mention of a regulator?

If you want a sold, dependable 0-5V, you're gonna have to put a regulator in situ. At least when the battery fades, you'll still have a solid 5V provided to the pot (else you'll have a diminishing max CV value as the battery fades)

Re why it's not wahing ....well if you *do* have 0-5v varying on the pot's wiper outpiut lug in sympathy with the wah pedal position, then there can be only one of two possibilities...

You are feeding the actual CV into the worng connector at the head end.

There's a fault with the remote cct. on the head unit.

In your position, I'd go back to basics.....get 5V (or near enough eg 3 x 1.5V= 4.5V) across a pot (It doesn't have to be 100k...all you seek is a varying control voltage between 0 & 5V ...also I'm suprised that it's an audio taper for a control voltage? You sure that's right - try a linear pot too)  take the wiper to the connector lug that it should go onto at the head end & the battery ground to your head unit's jack socket ground...try varying the pot, if it doesn't change the wah, then you can really hone in (try other connector lugs, etc)

[aron]

Use a meter as well to measure the voltage between the tip and sleeve. See if it does vary when you move the pot.

[4nkam]

He didn't mention any specific pot, just that it needed 5v and to use a battery for it. Using a TRS jack and the tip controls the wah, the ring enables it when theres enough voltage.

There is a 12v regulator on the rack circuit board.

Here's a portion of the schem where the CV pedal would connect to the rack unit:

[4nkam]

The pot wiper is definitely going from 0-6.42v. When I connect it to the switch and TRS jack, all I can do is turn the effect on/off. I set the pot to 3.8V then measured the jack. Tip/Sleeve shows 3.79v. Tip/Ring is 2.64v. Ring/Sleeve shows 6.41v.

[Gurner]

The pot wiper is definitely going from 0-6.42v

But you're after after 0-5V?

If I were a betting man I'd say 6.4v is not a show stopper & you've proved the pot aspect is ok, so I come back to the points I mentioned my earlier post, either there's a problem with the head (rack unit), or you are presenting the varying CV on the wrong head jack connection.