Maestro PS1-A Phase shifter

[johnk]

I've owned several vintage Maestro PS1-A  phase shifters way back in the early 70's and always really dug them, so I wanted to build one that used a standard 9V supply, had 3 foot switches for the speeds (instead of the three large colored rockers) and build it in a smaller enclosure for use as a pedal.
I found a pcb layout for one on diystompboxes so I though that i'd try and build one.

 this was to be my very first attempt at using the laser printer/glossy photo paper/copper etching method so I had no idea of how it would turn out. the layout posted was a little too large to fit in a 1590B so I photo-shopped it and 'bent' some of the traces to make it just a bit narrower.

well, i'm very happy to say that it fired up on the first try. my only issue with it was that it has a very low input impedance (around 33K) so you lose some level, as well as a lot of highs and some lows too. i'm going to solve that on mine with a simple Jfet buffer in front of the circuit ( I already tried it and it works great now).

anyway, here's some pics of the build so far:

[IvIark]

Excellent.  I was looking at that board before on DIYSB and thought it looked great.  Is it a copy of the original board or something?  I do love the look of that older style tracks etc.

[johnk]

yeah. it looks like a copy of the original's traces and layout. I just thought that with 10 transistors, 4 chips, and three trimmers it was a bit much to try and make a vero version of it.
it sounds frickin' great too.

[IvIark]

Yep with you on that one, sometimes vero is just too much of a pain in the arse for some circuits.  And when boards like this are available we can pick and choose the best time to use it.

[Heath]

You plan on etching any more?  You got a brutha feeling anxious over here.

[johnk]

not really. one of them is enough for me.
and drilling all of the holes was a beeocth.

[johnk]

She's done! and it sounds frickin' awesome.
the three small boards consist of a jfet input buffer, a negative voltage converter and a a jfet output booster with a level trimpot so I can adjust the output to match true bypass.

[IvIark]

Very nice

[rocket88]

just gorgeous.

[Heath]

johnk wrote

not really. one of them is enough for me.

Ha!  I get that.  Had to ask, though. :D

Damn fine job.

[johnk]

link to quick (and sloppy) soundclip:

https://soundcloud.com/johnk_10/ps1-a