Expression pedal input on the Harbinger One

[Cortexturizer]

How hard would it be to add one? And I am not thinking about the remote pot thing, but to make it usable with almost every type of exp pedals out there with the standard exp pedal pot values and all. This is one of those effects that I really feel the need for having an exp control over.
I have a couple of exp pedal enabled effects on my board, and am thinking of purchasing the Mission Expressionator, so I've been thinking about a univibe that will benefit from this as well. There is that Black Cat Pedals Vibe that fits the bill and that I've caught on classifieds recently, but from the looks of it inside it looks almost exactly harbinger-esque and I think I can build that no problem.

[RobA]

Which control do you want to put under CV? Do you want to control the rate or maybe be able to directly sweep the lamp?

Which other pedals do you want to control? I have the Stage Fright and the Flintlock that I've got setup for CV input and I'm interested in working on a CV system to control things with. I'd like it to be capable of working with some synth stuff too. Something like a combination of the Mission box and the Moog CV box would be really slick.

[Cortexturizer]

Hey Rob, always first to address my problems ))
Well, I'd like to adjust the Rate of the vibe. Also, when you say CV, it is my understanding that there are two kinds of exp controllable stuff, one is a passive way of doing it, so, it's through TRS jack and that way the pedal is generating a 0 to 5V voltage in itself and the exp pedal is there just to alter that voltage and control the parameter?? And the other way is through CV which is generated outside of the controlled pedal - in the exp pedal itself. Right? I am a bit confused there.

I was considering this thing as well - http://www.thomann.de/gb/amt_ex_50_mini_expression_pedald.htm because it can fit onto my pedalboard, I have just enough space. And I have a need for 2 or 3 exp outs. BUT, one out on the AMT is TRS and the other is TS. I already know as a fact that one guy that I've corresponded with on the interwebz couldn't control a way huge ringworm via the TS out. So what is this other out for, given that the AMT is a passive pedal?? I am confused Rob. Pretty confused.

[RobA]

... I am confused Rob. Pretty confused.

Me too. The CV situation on the A/DA flanger had me totally confused and I had to go back and forth between my Moog expression pedal schematic and the flanger schematic multiple time to get to the point where I think I've got it right. (I haven't really been able to test if I do have it right yet because the frequency counter on my DMM is totally non-functional.)

That little expression pedal is way cute . I think I want one. Their manual sucks though! 50k pot seems weird. Most look to be 10k or 25k. It looks like there's a toggle at the front of the treadle. Is that a bypass switch? Is that what's connected to the TS? If that's not it, maybe the TS is wired as a variable resistance?

I don't think the standards on expression pedals are very standard. I've seen at least two ways to wire the TRS jack. The Moog EP2 thing has an extra range pot that screws with the total impedance seen on the input and seems to serve very little purpose.

Overall, my take on the CV thing is what you wrote. The CV generator can be passive and get its input voltage from the device under control, or it can be active and generate the output CV itself. But, I don't think it really matters to the effect being controlled as long as the output and input impedances and the return voltage are within the specs it can handle. The manuals for the Moog synths and effects indicate that both are OK.

But, I'd guess that there are also some effects that don't really work with a CV and instead use the actual resistance of the pot. I can't think of any off the top of my head, but there has to be some. That's part of why I asked which pedals you wanted to use with it.

For the Harbinger itself, controlling the speed directly might get complicated because of the dual pot. Still, there's probably a way to think up doing it. You could do it with a dual digital pot and an MCU for sure, but all of them I've seen are limited to 1024 steps and that might cause zippering. 

[Cortexturizer]

Oh, so it might get really hard doing it. Bummer.
I intend to use the expressionator, once and if I've bought it (frankly I would, but the difference in price between USA and EU is off putting), with the DL4, Randy's Revenge and the Pigtronix EP-2. But I could live with two, so I've been lookin at the AMT due to that.
The switch on it's side is for the direction inversion. It would have been better if it would invert just one of the outputs, so that one could have em going in separate direction, but hey.
The expressionator is the way to go. It is SO nicely thought through. It has everything I need. It is expensive. But it is worth it.

[brejna]

Hi, I did son of  UVICS recently. So, if you want to control univibes rate with single 100k pot you can do it with vactrol VTL5C3/2 and few parts. Here is link
http://www.geofex.com/FX_images/UVICS-3%20Project%20File-3.pdf

[RobA]

It took me a bit to follow the schematic and the small boards on the UVICS doc, but I think I understand it now. The pot pretty much acts like a CV pot and the vactrol is wired so that the two sections replace the dual variable resistors of the SPD pot. So, you could make a little utility board that could drop in at the SPD pot connections on the Harbinger. To go out to a passive expression pedal, you'd just need to wire a switchable jack (or put it on a toggle) that selected for the wiper connection to the base of the transistor (Q15 on the UVICS) between the internal pot or the expression pedal return.

I just tried the vactrol control part on breadboard and it looks to work pretty well. I only have a VTL5C4/2 though and the taper with it was a bit weird. But, you could probably even do it with an LED and a couple of LDR's and make it work OK.

[Cortexturizer]

While their manuals do suck, their customer support is stellar I must say. Not only did I get a nice explanation very fast, but some of those guys actually went ahead and checked my pedal building blog out (that I've sadly neglected long ago) and made some nice comments. Hah! I was really surprised by that. Here's what Alexander from AMT wrote:

"If you want to control two TRS units, you don't need to have two TRS sockets,
moreover it's forbidden. TRS of unit usually have: sleeve-GROUND, ring-voltage, tip- center of POT(POT=25kOm in our case).
So if we'd have two TRS on EX50 we would simply cross circuit one unit's voltage to another unit's voltage.
In your case you should use two stereo cables (one to trs another to ts ). EX50 will get voltage only from the unit which is connected to EX50 TRS.
But you have to be sure that your units use equal(or close to equal) input parameters."

Weird that he wrote that the pedal is 25K when the manual and the site both say it's 50. Crazy Russians

[RobA]

Ahh, that makes perfect sense. So, you have to use the TRS jack and then the TS jack will also work, but only if the two effects use the about same input voltage on the ring. That seems to also indicate that they are setup using the Moog standard for the jacks. That's good to know too.

Is that a stomp switch under the treadle in the photos? Do you know what it does?

[Cortexturizer]

Hm, looked like it on a couple of pictures to me too, but then I found this picture - http://image.rakuten.co.jp/auc-ksound/cabinet/efc/img62601444.jpg
So no switch