Mutron Phaser II: Schemo or builds?

[dano12]

I searched high and low, came up dry.

Any schemos available for the Mutron Phaser II?

[Sir H C]

Thought someone posted it here pretty recently.  Like a month back or so.

[dano12]

Thought someone posted it here pretty recently.  Like a month back or so.

There was a link to this: http://www.sonicurbs.com/mutron2/schem.jpg

Pretty much unreadable...

[Dragonfly]

I believe this was the final revision..


page 1 ..  http://img.villagephotos.com/p/2008-4/1304854/mutronphasoriipg2kt1.gif

page 2 ..  http://img.villagephotos.com/p/2008-4/1304854/mutronphasoriipg1yf6.gif

[dano12]

I believe this was the final revision..


page 1 ..  http://img.villagephotos.com/p/2008-4/1304854/mutronphasoriipg2kt1.gif

page 2 ..  http://img.villagephotos.com/p/2008-4/1304854/mutronphasoriipg1yf6.gif

Awesome! Thanks much.

[Dragonfly]

I believe this was the final revision..


page 1 ..  http://img.villagephotos.com/p/2008-4/1304854/mutronphasoriipg2kt1.gif

page 2 ..  http://img.villagephotos.com/p/2008-4/1304854/mutronphasoriipg1yf6.gif

Awesome! Thanks much.

I hope it helps. I forget who did the actual "work" on it...If I remember, I'll send him a "thank you" note ! 

[Derringer]

I have a Phasor II that I've been periodically debugging.
It'll work fine for a while and then go intermittent.

I replaced all of the electrolytics and that seemed to really help, but it still gets glitchy every now and again.


Anyway, what exactly is this thing here in the picture?
Am I correct in assuming that it's an LDR?

[dano12]

I have a Phasor II that I've been periodically debugging.
It'll work fine for a while and then go intermittent.

I replaced all of the electrolytics and that seemed to really help, but it still gets glitchy every now and again.


Anyway, what exactly is this thing here in the picture?
Am I correct in assuming that it's an LDR?

Yeah, it is the funky Mutron LDR.

It is actually a single light source surrounded by six LDRs, hence the six-stage phaser.

Small Bear sells the Hammatsu LDR part for repairing Mutrons, but I'm not sure it is the same one as on the Phasor II.

I'm breadboarding the Phasor II as a project this week--the tough part will be making a home-made six-stage vactrol

[soggybag]

An interesting note on the First scheme post above. There is a diode going to the Vcc (I think that's the term for the positive power connection) of the LFO op-amp. My guess is this is a trick to help eliminate clock noise.

[Mark Hammer]

There are some decent quality factory schems around.  I know I have the jpegs at home.

Note that while there are certainly requirements for the LDRs to respond in a relatively homogenous way, there is NO requirement to match LDRs in a phaser the way there is a requirement to match FETs.  As long as they respond to the same light, and cover roughly the same (and appropriate) resistance range, you're in good shape.  Happily, the response time is not as critical for a phaser as it would be for a noise gate or compressor.

[mdh]

Yeah, it is the funky Mutron LDR.

It is actually a single light source surrounded by six LDRs, hence the six-stage phaser.

Small Bear sells the Hammatsu LDR part for repairing Mutrons, but I'm not sure it is the same one as on the Phasor II.

I'm breadboarding the Phasor II as a project this week--the tough part will be making a home-made six-stage vactrol

The Hamamatsu P873-13 sold by Small Bear is the dual-LDR, single-LED photocoupler for the Mutron III Envelope Filter (aka R.G.'s Neutron).  They also carry Hamamatsu P722-7R, which appears to be just an LDR.  Also, I just noticed this part, which they seem to have binned into a bunch of ranges for $0.95 each.  Looks like a bargain to me, if the  ranges really are reliable enough.

It's about time the Beavis philosophy was brought to bear on 6-stage optical phasing!  I look forward to hearing the results!