Muff's Modules & More

E.A.S. · Posted: Fri Jul 20, 2012 6:34 pm Post subject: BUILD THREAD: MISS 10 VCO 2.0

The VCO pcbs are in and will be shipping very soon!
This VCO is different enough to justify starting a separate build thread for this version.

MISS 10 vco 2.0 w/panel by itsfatmike, on Flickr

MISS 10 VCO 2.0 by itsfatmike, on Flickr

E.A.S. · Posted: Fri Jul 20, 2012 6:35 pm Post subject: schematic.

Schematic.

MISS TEN VCO rev 2.0 by itsfatmike, on Flickr

PW MIXER by itsfatmike, on Flickr

Wiring diagram.

IMG_7239 by itsfatmike, on Flickr

Notes:

An Error in my silkscreen! ALL transistors need to be installed "backwards" with regard to the silkscreen.

Vref output is a buffered voltage reference I included for connection to the Hz/v input. you can jumper it directly (as seen in the photograph and schematic) if you don't plan on using the Hz/v input. Or you can "normalize" the Vref to the "switching lug" on the Hz/v input. The Hz/v is not labeled on the wiring diagram, but it is on the pcb. Its between the octave switch and the wave outputs.

The PWM jack would probably be best served with attenuator pot, wired like the pitch cv inputs.

The square output resistors mounted to the jack are 22k (from the pcb to the tip) and 2.7k (from the tip to ground)

E.A.S. · Posted: Fri Jul 20, 2012 6:35 pm Post subject: Bill of Materials.

Bill of Materials.

Mouser part #'s included.

pre55ure · Posted: Fri Jul 20, 2012 9:56 pm Post subject:

I want one!
Is it too late to order?

ringstone · Posted: Sat Jul 21, 2012 1:56 am Post subject:

Hmmm... interesting! Good to see some extra room for the precision resistors. Are the two holes underneath Q6 to enable the use of a 2SC1583 if desired, or am I mistaken?

Also, I assume that the extra opamp on the ramp waveform is to invert it so that it ends up a saw? I still don't understand how it ends up a saw on the MS-20... does one of the filters have an inverted output and the other not?

Tossing up whether to get some of these as well...

Cheers
Blair

steffensen · Posted: Sat Jul 28, 2012 1:19 pm Post subject:

There's just one thing from the BOM that im not sure on what to get. Perhaps someone could help me locate the right part? Its the SW1 - SCALE - SP4T

Not sure what to look for, never used a switch like this before. Is it a switch trimmer, controlled by VR11?

Edit: Nevermind, found the answer in another thread. meh

Are the shipping closing in btw? smile

E.A.S. · Posted: Sat Jul 28, 2012 4:09 pm Post subject:

steffensen · Posted: Sat Jul 28, 2012 4:28 pm Post subject:

E.A.S. · Posted: Tue Aug 07, 2012 7:57 pm Post subject:

wiring diagram added!

steffensen · Posted: Wed Aug 08, 2012 4:33 am Post subject:

Looking good. grin

simfonik · Posted: Wed Aug 08, 2012 10:47 am Post subject:

Are there still v2.0 PCBs available?

E.A.S. · Posted: Wed Aug 08, 2012 4:22 pm Post subject:

Rod Serling Fan Club · Posted: Sun Aug 12, 2012 10:39 pm Post subject:

Aside from checking the leg placement can I just swap the transistors shown on this schematic/bom on the first PCB?

I'm utterly frustrated with my vco build. It's such a simple PCB but I can't get it to make sound. I think all but 1 of my transistors were alternates as it is and I had to swap them around due to wrong leg placement and now I question datasheets as I'm not 100% certain who the manufacturer was on some I have.

I think I'm ready to replace all the transistors at this point.

E.A.S. · Posted: Sun Aug 12, 2012 11:10 pm Post subject:

Rod Serling Fan Club · Posted: Mon Aug 13, 2012 11:02 am Post subject:

ringstone · Posted: Wed Aug 15, 2012 1:05 am Post subject:

asterisk · Posted: Fri Aug 24, 2012 7:48 pm Post subject:

where the hell is R1? i cant find it on the PCB.
is it where the unmarked SMT / through hole spot is? is that R1?
and is that an either / or situation? you can choose to have TH or SMT, not BOTH?

please let me know, im working on populating my 2.0 board.
thanks.

E.A.S. · Posted: Fri Aug 24, 2012 8:00 pm Post subject:

Rod Serling Fan Club · Posted: Fri Aug 24, 2012 8:05 pm Post subject:

E.A.S. · Posted: Fri Aug 24, 2012 8:07 pm Post subject:

Oh, regarding the Tempco, its either/or. The tempco is R8 (unmarked on the pcb) but is the only spot for SMT. in the same area is pads for TH as well.

-M

asterisk · Posted: Fri Aug 24, 2012 8:11 pm Post subject:

ok duh, i was getting R and R1 confused.
thanks.

do you have a mouser part # for the TH version of R8?
i think the part # you have on the BOM is just for the SMT version.

never mind, SP4T switch mouser # is = 105-SR10010F-24NS

thanks!

E.A.S. · Posted: Fri Aug 24, 2012 8:30 pm Post subject:

E.A.S. · Posted: Fri Aug 24, 2012 8:35 pm Post subject:

RSFC, To keep the V1.0 and V2.0 note separate, I replied to you question Here.

-Mike

Lockheed · Posted: Sun Sep 23, 2012 3:48 pm Post subject:

I've built the Miss10 v2.0 and it mostly works. Two problems though: first, the triangle wave output is very low amplitude, and it looks like the other end of R76 is not connected to +V on the PCB like the schematic shows or do I read it wrong?
Second, the pulse width pot (1M lin) has a very short working range. The pulse width changes at first, but turning the pot a little more or so, the pulse output suddenly goes dead silent and stays silent for the rest of the range. Sound returns after turning back to low setting. Same happens with external voltage. Looks like the threshold is at 0.7 volts or so, going over that the pulse output goes silent.

I'll get back to testing in a couple of days when I got the time, but if anyone has some thoughts in the meantime, I'd appreciate it.

ikkini · Posted: Fri Oct 05, 2012 2:04 pm Post subject:

I've started, but can't find R4 on the PCB !!!...

steffensen · Posted: Tue Oct 23, 2012 11:45 am Post subject:

ikkini · Posted: Sun Dec 02, 2012 1:43 pm Post subject:

Argh ! I soldered the transistors the wrong way !!!! very frustrating

steffensen · Posted: Sun Dec 02, 2012 1:46 pm Post subject:

E.A.S. · Posted: Sun Dec 02, 2012 2:06 pm Post subject:

steffensen · Posted: Sun Dec 02, 2012 2:17 pm Post subject:

ikkini · Posted: Sat Dec 22, 2012 9:30 am Post subject:

I've tried to remove my transistors, impossible. I've cut them all, but the PCB seem to be damaged now... I fear I will never finish this... cry

Why didn't you mention on the BOM that the transistors went the wrong way ??? cry

negativspace · Posted: Sun Apr 21, 2013 6:43 am Post subject:

Lockheed · Posted: Sun Apr 21, 2013 5:36 pm Post subject:

negativspace · Posted: Wed Apr 24, 2013 11:23 am Post subject:

Ok, so I finally had time this morning to poke at this. Looking at the two schematics side-by-side, I think what's happened is that the PWM opamp was switched to an inverting configuration to sum the panel pot + PWM CV but there is no second inverting stage to get the original polarity back. To confirm this I disconnected the WIDTH pot from the +12v rail and hooked it to the -12v. Bingo, PWM just as it should be.

To fix the range so that you get ~95% of the pot's rotation before sound cuts out, connect -12v to the CW lug of the WIDTH pot in series with a 680k resistor.

That'll fix the panel pot, but what about the CV input? Using 0->-5v to modulate it rather than 0->+5v should do the trick. (Mine seems to cut out at about -4v, but you get the idea.) Got enough CVPs? hihi

I can "fix" this on the daughterboard I have almost ready by adding an inverting stage to the PWM CV input with an SMT opamp. That plus the 680k resistor to -12v on the width pot will make it work as intended. I'm just not sure there's still interest in the daughterboard? Maybe I should re-open that thread.

steffensen · Posted: Wed Apr 24, 2013 11:54 am Post subject:

lombrose · Posted: Sat Apr 27, 2013 1:04 am Post subject:

there is still the v2 vco board to buy?
Mr. Green

E.A.S. · Posted: Sat Apr 27, 2013 12:53 pm Post subject:

E.A.S. · Posted: Sat Apr 27, 2013 2:21 pm Post subject:

Hey Jason, (and others)

I just poked around as well and found an even simpler fix. w00t

The feedback resistor in the mixer section just needs to be reduced to 30k to reduce the gain on the mixer. You'll also want to raise the initial PW pot input resistor to 240k. By changing the feedback resistor it also takes care of the other inputs at the same time, so no other changes need there. If you want to wire the initial PW pot between +12v and -12v it'll give you full sweep through the pulse width ratio. otherwise it'll only do pulse to square.

heres a quick drawing...

PW MIXER by itsfatmike, on Flickr

thumbs up

-Mike