Muff's Modules & More

Ianh · Posted: Wed Feb 22, 2012 3:14 pm Post subject: Thomas white LPGc questions

Hey guys i got my pcbs and am going to make my parts order soon. Before i do i had a couple questions about some features i wanted to add (or maybe they are already there) and wanted to make sure i got all the parts for it.
The first thing i would like to do is have voltage controle over the resonance (doesn't seem like this is implemented). I also wanted the resonance pot to act as an attenuator when i had incoming cv. I know i would need a switching jack but after that i am not really sure.
I also wanted to install two dual vactorals and have the ability to switch between fast and slow vactorals. In my mind these are both simple things to accomplish but i have found these types of mods are more complex than they appear.
p.s. this will be my first build.
thanks guys

jumunius · Posted: Wed Feb 22, 2012 3:41 pm Post subject: Re: Thomas white LPGc questions

Ianh · Posted: Wed Feb 22, 2012 4:12 pm Post subject:

cool thank you this is very helpful for the vactrol set up. Definetly need to do research. Im sure other people would be interested in a res cv mod so perhaps more searching is in order for this as well.

valis · Posted: Wed Feb 22, 2012 4:24 pm Post subject:

For voltage control over the resonance circuit it'd probably just be easiest to add a vactrol to the circuit. Some tweaking may be required to get the suitable response. Check out bridechamber's voltage controlled resistor.

http://bridechamber.com/VC_Res_PCB.html

fonik · Posted: Wed Feb 22, 2012 4:53 pm Post subject:

maybe it would be even easier by adding two sockets (res out and in, out normalled to in) and to do the voltage control by an external VCA that is part of the modular already.

Ianh · Posted: Wed Feb 22, 2012 5:05 pm Post subject:

negativspace · Posted: Wed Feb 22, 2012 5:49 pm Post subject:

Ianh · Posted: Wed Feb 22, 2012 8:15 pm Post subject:

jumunius · Posted: Wed Feb 22, 2012 11:50 pm Post subject:

Ianh · Posted: Thu Feb 23, 2012 1:00 am Post subject:

If any one would care to offer an explanation of how to set up matthias'/negativespace's suggestion i would be very grateful.

fonik · Posted: Thu Feb 23, 2012 4:39 am Post subject:

i will try, refering to the rev 3.0 schematic:

for the res mod there are two jumpers: JP1 and JP2.

i would insert the out/in sockets right before U1, so that you could still use the res pot for attenuation.

1st solder a wire bridge to connect JP1A and JP2A.

2nd solder a wire from JP1B to your "res out" socket tip AND to the switching contact of your "res in" socket.

3d solder a wire from your "res in" socket tip to JP2B.

how does it work? resonance is a feedback. you just hack into this feedback loop with your out/in sockets. if you don't plug a chord into the in socket, the signal from the out socket is applied. as soon as you plug a cord in, signal from the out socket is disconnected.

i believe this option would enable further experiments with processing the feedback, and/or applying other external signals.
the more i think of it, the more i want it to try myself hihi

edit: spelling

Ianh · Posted: Thu Feb 23, 2012 9:15 am Post subject:

Thanks matthias! That makes perfect sense. Can't wait to get this set up!

Ianh · Posted: Thu Feb 23, 2012 12:18 pm Post subject:

This must be very annoying but just to insure that i understand (and perhaps for benefit of others doing this mod i drew up the mod on the 3.2 pcb.

Just out of curiosity if i pluged a jack into the out only would i be able to use that signal and leave the loop un affected? Or would i need to buffer it some how.
Thanks for bearing with me.

fonik · Posted: Thu Feb 23, 2012 4:04 pm Post subject:

your picture looks good to me, at least does it show what i meant.

Ianh · Posted: Fri Feb 24, 2012 2:04 am Post subject:

Awesome thank you very much!

jumunius · Posted: Fri Feb 24, 2012 2:36 am Post subject:

fonik · Posted: Fri Feb 24, 2012 3:04 pm Post subject:

let's wait for the results hihi

Ianh · Posted: Fri Feb 24, 2012 5:21 pm Post subject:

I am ordering parts after i finish my current project. If any one implements this mod before i do my build i would love to hear the results.

fonik · Posted: Sat Feb 25, 2012 8:28 am Post subject:

i applied the mod today. took me just a few minutes to drill the two additional holes and wire it up.

uploading a sound is no use, since the mod does not change anything in sound. it is just that you control the amount of the resonance feedback with an external VCA. filters with voltage controlled resonance have an internal VCA, that's all. often this VCA is OTA based, stripped down versions of a common OTA based multipurpose VCA.

i am not sure if you wanted to use a linear or an log VCA. i did not have the time to test this in depth...

anyways, the mod does not change anything of your internal circuitry so it is worth it anyways if you only can afford the real estate in front panel.

astroschnautzer · Posted: Sat Feb 25, 2012 11:50 am Post subject:

fonik · Posted: Sat Feb 25, 2012 4:27 pm Post subject:

a while ago i tried feeding back the summed out to the input. the result was a very harsh resonance, very noisy. maybe i should try inverting it? or as you said: just using a single out...

Ianh · Posted: Sat Feb 25, 2012 6:42 pm Post subject:

astroschnautzer · Posted: Mon Feb 27, 2012 10:43 am Post subject:

fonik · Posted: Mon Feb 27, 2012 4:19 pm Post subject:

astroschnautzer · Posted: Mon Feb 27, 2012 4:50 pm Post subject:

fonik · Posted: Mon Feb 27, 2012 5:10 pm Post subject:

astroschnautzer: check PM!

(we are very off topic right now)

nihilist · Posted: Mon Feb 27, 2012 5:14 pm Post subject:

Not sure if anyone else has experienced this.
BUT
I built a dual LPG and it was working fine,
then last week the output level has "sharply" decreased
and is giving off a hum, due to not being grounded.

SO, I am not sure why it was working just fine,
and isn't now...

Anyone?

bsmith · Posted: Wed Mar 07, 2012 6:43 pm Post subject:

Newb diy'er confused trying to order shit alert!
Ordered a couple boards and I'm going to build some other things before I get to these but I'm trying to build a project in mouser for parts - a few things are challenging me..
Going by the list with part #'s specified in DJ Thomas' bundle of docs there are these polystyrene caps that are obsolete, and all similar rated polystyrene film caps are as well. Specifically:
Polyester Film Capacitors 250volts .1uF
and
Polyester Film Capacitors 63V 1.0uf
and then also this resistor:
Carbon Film Resistors - Through Hole 4.7Mohms which is backordered 14 weeks out.
Can anyone recommend parts that would work or a way to approach this?
Sorry if these are dumb/easy questions - just getting going with this stuff.

jumunius · Posted: Wed Mar 07, 2012 7:52 pm Post subject:

negativspace · Posted: Wed Mar 07, 2012 8:19 pm Post subject:

You can also shift-click in the Mouser category lists to select multiple categories for a search - so click 35v, 50v and 63v + 1.0uF with polyester caps for example. From there click on 5mm lead spacing + radial and see what you have left.

bleeps · Posted: Wed Mar 07, 2012 8:33 pm Post subject:

Hitching a ride on bismith's question: Does a specified lead spacing affect anything other than fitting into a particular PCB layout? In other words, is it okay to sub something with a different spacing if that's what you have on hand provided all other specs are compatible?

bsmith · Posted: Wed Mar 07, 2012 8:34 pm Post subject:

Thanks so much guys - this is a project that's quite a ways off, have a bunch of other very cool things closer to the level I should be working on to make my way up to these - wanted to at least get the boards in case they became unobtainable. Thanks for the mouser hunt tips - sometimes it kind of seems to present me with an easy way to get related parts and sometimes not - or something.
I don't know where the hell I pulled 'polystyrene' from!

gwaidan · Posted: Wed Mar 07, 2012 8:54 pm Post subject:

jumunius · Posted: Wed Mar 07, 2012 11:47 pm Post subject:

cleaninglady · Posted: Sat Mar 10, 2012 7:46 am Post subject:

e-grad · Posted: Sat Mar 10, 2012 8:06 am Post subject:

cleaninglady · Posted: Sat Mar 10, 2012 9:15 am Post subject:

e-grad · Posted: Sat Mar 10, 2012 9:42 am Post subject:

jumunius · Posted: Sat Mar 10, 2012 10:38 am Post subject: