Vox Repeat percussion questions

[daydreamdelay]

I recently got ahold of the corrected schematic and want to build one but I've never done anything beyond PCB kits.. I'm thinking about getting some pad per hole perf board from RS and giving it a go or maybe building a small boost or two first to figure out how to work with perf. I know a few of you have built these so beyond looking back at old threads which I've done plenty of I'd like to get some current thoughts on this build.. especially from anyone who was also new to perf and if possible I'd love to see some pics of completed projects to get a better grasp on how to put it together.

also..

are any of the parts difficult to source?

would it be difficult to add a depth knob?


thanks

[doug deeper]

the unijunction transistor may be bit hard to find...but!!!
small bear has them listed in the diode section of the stock list.

[daydreamdelay]

thanks.. I noticed that and the link in one of the threads, I'm placing an order through Mouser right now for some other stuff so I'll have to do some digging and see if it's available from them as well, if not then I'm sure there's some stuff from SBE anyway


anyone have pics to share?

[stobiepole]

I think this is what you wanted:





Nothing special or great about the layout - it's a pretty simple build, so you've got plenty of room. But it's a nice build, and definitely worth giving a go. The only tricky thing is making sure you have the pinout right for the unijunction transistor. You'll probably notice I had to twist the legs around...

Chris

[daydreamdelay]

excellent! that's going to help quite a bit.. thank you!!

I remember reading about the legs on that transistor needing to be twisted.. so basically the middle leg goes in outside socket and the outside leg goes into the middle socket.. correct?


so can anyone tell me how I'd go about adding a depth control to this circuit.. I assume it's possible but being new to all of this I have no idea how to go about it 

[stobiepole]

Yep, the middle leg goes to one of the outer sockets. It works if you kind of turn the whole transistor ninety degrees...

I'd build it and get it working before worrying about a depth control. I don't think it's the pedal to be building if you want to control the depth - you might be better off with the EH Pulsar or the Tremulus Lune. The Vox has a very distinctive sound, which is a strength, but also a weakness. I don't think a depth control would be that usable...the temptation to add more and more knobs is always great, especially when you're starting out. And it depends upon the effect - some become much more usable with more control, like the Bass Balls. Other times, you just get unusable results, or so little difference that it's not worth it.

The nice thing about one knob pedals, like the Vox, is that you don't have to add a label. From the perspective of an interface designer, that's a very good thing.

Chris

[daydreamdelay]

yeah I'm going to build it to specs just to get it up and running but I'm just curious if anyone has added a depth knob and how best to go about it.. I noticed the Ronsound has it and the clips sound fantastic so I figured if it's a simple enough mod I'd try it. I definitely don't mind a one knob pedal though, I tend to like the simplicity of set and forget pedals

I was just going through Smallbear's site and noticed the other two transistors aren't listed.. for BC108A I see BC108, BC108B and BC108C.

so is BC108 in actually BC108A?

and for the BC109B I only see BC109 and BC109C listed

[Gripp]

I'd really like a copy of the corrected schem too.
Could any of you kind souls mail it to Grillbeppe(at)hotmail.com, please?

Best!
Pelle

[daydreamdelay]

sent 

[Gripp]

Thanks a lot!
I might have made a mistake in an effort not to make my mail address so available . Should be no () surrounding the at in my real mail address...
Sorry about the mistake and if you didn't write them and/or hotmail is just slow (as it often is) then just, thanks again!

[daydreamdelay]

probably just slow.. i replaced the (at) with @

if it doesn't show up in the next few minutes let me know and I'll try again

[Gripp]

Unfortunately no schem in the mail yet.

Btw, those A's or B's are there to tell what gain range the trannies are sorted in.
Check out this datasheet: http://www.ortodoxism.ro/datasheets/SGSThomsonMicroelectronics/mXvtryv.pdf
On page 2, the HFE of the different grades are given, so a BC108A is between 110-220 and a B is 200-450 and so on.

I don't know if gains are crucial in the repeat percussion and don't think so, but that would be easier with a correct schem.
In this post, there's some more discussion about the R P.

[stobiepole]

Besides the unijunction transistor, the others aren't critical. But when in doubt, socket them. I used BC548s, which are standard plain European/Australian low power trannies that sub for BC108s. But, you know, keep some 2n5088s handy...

Chris