Messing With Dr Phybes

[Chuck]

Okay, I’ll admit to having a pretty serious phaser addiction that I don’t ending in the foreseeable future.  Got another Dr Phybes on the way and this one will get the 45/90 switch, Depth pot mod and rate indicator LED.  I’ve also been digging around to find other interesting changes and/or useful mods.  Here’s a short list of what I’m pondering:

1. Jumper SW1 and replace R16 with a pot for an adjustable feedback control – for those times you want more swoosh or less.

2. Found some discussion on the web that using a 3M3 in place of the 3M9 (R23 in Dr Phybes) will yield a “wider phase” – what ever that means.  There’s also some discussion that increasing the ratio between R25 (470K) and R26 (150K) – increasing R25 while decreasing R26 – will yield a “wider phase”.  It’s on the web it must be true – socket and see?

3. I’d like to slow down the slowest rate – would increasing the value of C8 from 10N to 22N slow things down, or increasing C9 from 10UF to 22UF, or increasing P1 from 500KC to 1MC?  Found a lot of back and forth on this with very little (if any) agreement.  Maybe I should just be happy with the tap tempo in my Liquid Mercury build.

Any tips, warnings, or good thoughts would be appreciated.

Chuck

 

[Anonymous]

1.  You can also reduce R16 to 10K and install a B20K pot in series with lugs 1 and 2 shorted ( to act as a variable resistor).
2.  Reducing R23 to 3M3 will increase the average voltage produced by the oscillator.  This will change the balance of the signal fed to the gates of the FETs which is offset by the constant voltage provided through TR1.  After readjusting the TR1, you may notice a change in the range of the phase effect.
3.  Increasing the C8 value will slow the oscillator by changing the time constant of the oscillator.

[Chuck]

Thanks Wilkie.  Will use sockets and see what it does.

Chuck

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