Mutron Micro V (+?) build guide

[Mustachio]

Awesome nice work Leo! Happy to hear its working for others!


I hope ya get it working Rob, I know when I was working on this I was getting mixed up with the arrows pointing up that are to show v ref of 4.5v or 9v they almost look like ground symbols and it threw me off a few times, had to do a double take 

I have been pretty busy and haven't sat down and messed with this circuit any more but I have a few ideas and tweaks in mind. I think this can be improved on a bit more even though it sounds pretty dang good how it is. I'll let you guys know when I got something. In the mean time I hope some of you guys do a build of this so I can hear it and hear your thoughts. I can probably etch a few pcb's if anyone is wanting one.

Cheers! And happy new year,

Jimmy

[J0K3RX]

FYI - Check this out, super simple online schematic drawing app for future reference.
http://www.digikey.com/schemeit

[Mustachio]

Nice Joker! Perfect, I'll try to redraw this in the next few days using that. I was going to just start drawing in photoshop but this will be easier in the long run thanks man!

[deadastronaut]

@leo,  nice one, must be just me then..

i'll give it another go today,


@jim/jokerx: cool link, bookmarked.

[nocentelli]

@leo,  nice one, must be just me then..

i'll give it another go today,

I didn't have all of the suggested parts, so I used BC549c for Q1+2, 2N3906 for Q3, and a 1458 for the dual. It was a pain to breadboard, with loads of flying leads all over the place, so I was pretty surprised it worked first time for me.

I have been pretty busy and haven't sat down and messed with this circuit any more but I have a few ideas and tweaks in mind.

First thing that crossed my mind was a switch to lift the "doubled" pins for less intensity. Also I'm using just half of a DPDT on-off-on switch for the Hi/Lo, so I'm going to put a different R11/C10 pair on the other half for a "medium" position.

The other thing that would probably be worth trying is a simple fuzz inserted in a loop somewhere (maybe after C2?) for a filtered fuzz sound.

I can probably etch a few pcb's if anyone is wanting one.

Cheers! And happy new year,

Jimmy

I'd be very pleased to purchase one or two if you get around to etching some - I'm doing a vero now, but it's going to be larger than is ideal for a single knob pedal.

Happy New Year! Great first circuit of 2013.

[deadastronaut]

@leo: cool at least i know the 3906 will be ok,   

my breadboard is a mess too...

[deadastronaut]

right breaded again..

only getting filter when manually changing R16/470K  up n down in value (with resistor sub box) , but no autofilter though, hmmm....

and pot doesn't do anything (500k trim) not 1M...i'll swap that n see...anyway here we go...

4558

1 4.96
2 4.97
3  4.97
4  0.00
5  4.97
6  5.21
7  5.50
8  9.11

13700n

1  1.14
2  0.00
3  4.96
4  4.97
5  4.97
6  0.00
7  0.00
8  0.00
9  0.00
10  0.00
11  9.11
12  4.97
13  4.97
14  4.97
15  0.00
16  1.14

c1 2n5088  (power)

C  9.11
B  5.51
E  4.97

C2 5088 (input)

C  9.11
B  4.79
E  4.23

2N3906

C  1.14
B  4.98
E  4.96

[nocentelli]

Ok, I'll check mine in a minute: Just to note, I've got a 470k R16, and I used a 1MC pot, as the useful stuff seems to be up at the higher end of the scale, so there's a better resolution over the upper range with a reverse log pot: You could maybe try a 470k in series with your trimmer for control pot. I'll post voltages ASAP

[deadastronaut]

cheers man, i'll try that on the trim,  got to nip out for a bit so no rush ok.  thanks.

[Mustachio]

Man If I would have seen this post an hour ago I would have taken some voltage readings for ya. I was downstairs messing with the superfly.

I would be careful swinging R16 around to much. this controls the current to the OTA bias and if it goes over 2ma I think it will fry the chip. I would work on getting just one side of the lm13700 working first since its on bread board, this is what I did originally. Once you have one side working alone then you can jumper to the other side and change r16 to 500K or near it. I actually used two 1m in parallel to get 500K but 470K should be close enough.

Just from memory the IC's look ok but q1 and q2 look a little off . Ill get some readings as well and post em with nocentelli so we can get more info on this circuit posted for future reference.

[nocentelli]

So I had a bit more of a play, and noticed some unpleasant clipping when playing chords a little harder: Swapped the 1458 for a 5532 but clipping still there - I'm using humbuckers, but not super hot ones..... Hmmm. Anyway, here are my voltages:

Power = 8.27v
Vref = 4.44v

Rob's || Leo's

4558 || 5532

1 4.96 || 4.44
2 4.97 || 4.44
3  4.97 || 4.44
4  0.00 || 0
5  4.97 || 4.44
6  5.21 || 6.8
7  5.50 || 6.8
8  9.11 || 8.27

13700n

1  1.14 || 1.13
2  0.00 || 0
3  4.96 || 4.43
4  4.97 || 4.43
5  4.97 || 4.60
6  0.00 || 8.27
7  0.00 || 0
8  0.00 || 0
9  0.00 || 0
10  0.00 || 0
11  9.11 || 8.27
12  4.97 || 4.6
13  4.97 || 4.43
14  4.97 || 4..43
15  0.00 || 0
16  1.14 || 1.13

"c1" 2n5088|| 549c  (power)

C  9.11 || 8.27
B  5.51 || 4.92
E  4.97 || 4.44

C2 5088 || 549c (input)

C  9.11 || 8.27
B  4.79 || 3.97
E  4.23 || 3.77

2N3906 || 2N3906
C  1.14 || 1.13
B  4.98 || 4.25
E  4.96 || 4.40

Seem compartable - I've got the power hooked up exactly as per scheme, my "onespot" puts out 8.97v so I assume the drop is due to the 1N4148

[Ronan]

Rob, it looks like something is wrong around pins 6 and 7 of the 4558.
(But the more I look at the figures, the more confused I become...)

[nocentelli]

Rob, it looks like something is wrong around pins 6 and 7 of the 4558.
(But the more I look at the figures, the more confused I become...)

Thanks for having a look, but I just re-checked those voltages (along with the whole of the dual), and the readings I initially gave for those two pins were wrong   It should be:


Rob's || Leo's

4558 || 5532

1 4.96 || 4.44
2 4.97 || 4.44
3  4.97 || 4.44
4  0.00 || 0
5  4.97 || 4.44
6  5.21 || 4.44
7  5.50 || 4.64
8  9.11 || 8.27

Which looks like we have the same situation, just scaled for the different voltage supplied.... hmmmm

[armdnrdy]

Power = 8.27v
Vref = 4.44v

Rob's || Leo's


13700n

1  1.14 || 1.13
2  0.00 || 0
3  4.96 || 4.43
4  4.97 || 4.43
5  4.97 || 4.60
6  0.00 || 8.27
7  0.00 || 0
8  0.00 || 0
9  0.00 || 0
10  0.00 || 0
11  9.11 || 8.27
12  4.97 || 4.6
13  4.97 || 4.43
14  4.97 || 4..43
15  0.00 || 0
16  1.14 || 1.13

Voltage on pin 6 of the 13700? That doesn't seem right. Pin 6 should go to ground.

[Ronan]

Yeah, just a typo I think, since Leo's circuit works.

Heres the schem again:
http://i198.photobucket.com/albums/aa160/birdy81260/MustachioMutronMicroVvariant.jpg

I still think there's a prob with Robs circuit, because pin 7 of that IC should be trying to pull pin 6 a bit lower to match pin 5. i.e. whatever pin 5 sits at, with no guitar signal, pin 6 should be the same, and if it isn't, pin 7 should increase or decrease its voltage to make pin 6 = pin 5. In Rob's circuit, pin 6 does not equal pin 5, and pin 7 is swinging in the wrong direction (higher still).

[nocentelli]

Yep, my typo: Pin 6 of the OTA is 0v

[deadastronaut]

cheers guys,  i'll see if i can get some time on this  tonight, i have my 4 year old grand daughter today...lots of fun and noise...sort of..

i'll wait till its her bedtime...

i'll check around that opamp...

[Perrow]

i have my 4 year old grand daughter today...lots of fun and noise...sort of..

Four year old kids are excellent noise generators

[garcho]

White noise, or pink noise? I think my nephew makes brown noise.

Just got Thomas Henry's book on the 3080, just breadboarded Merlin's compressor (Engineer's Thumb), been putzing with MS-20 series filters, gonna build the Mutron V soon, man, I love these OTAs! Has anyone messed with CV-in for the Mu5?

[nocentelli]

Not yet, but I like the idea of trying the Micro V envelope section to trigger an MS-20 LPF