MODIFICATION Teaser: I've got a Circulator mod in the works

Chuck D. Bones

Circuit Wizard
Have not. Looks interesting. Easy to breadboard. I'm familiar with the fixed phase stages, used it in an experimental MOSFET-based UniVibe. Still tweaking that one.

I should add that the Phase 100 has four fixed phase stages. That's the first place I saw the fixed phase being used.

I hooked up my Circulator again earlier this evening. It does a pretty good UniVibe imitation.
 
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Chuck D. Bones

Circuit Wizard
I should add that my RANGE switch is ON-ON. I'll try the LFO kill on my breadboard to see what happens.
OK, so I finally got around to trying out the ON-OFF-ON range switch. It kills the LFO and turns the SWEEP control into a manual control, just like on the un-modded Circulator. To me, phasers only sound good when they're moving, so I won't be replacing the ON-ON RANGE switch in my Circulator with an ON-OFF-ON switch.
 

bkn1966

New member
I hate to be a noob, but I have a couple of questions regarding the 14 point mods (and thank you by the way).
Mod #4.) resistors in series? So, if I understand you, it’s going to be 2, 10k resistors connected at one end and the others on pin 1 and 16?
#6.) the diode mod on the sweep pot? My question would be about orientation, a pic would be great.
Thank you for your time
 

Chuck D. Bones

Circuit Wizard
Check the last pic I posted. It shows how I installed the diode. It's a little hard to see, the cathode band is down.
There are a total of four 10K resistors, two on IC1 and two on IC2. From pin 1 to the pad on the board and from pin 16 to the pad.
 

Guybrush

New member
Hey Chuck. Thanks for the mods! Just ordered the parts to make the circuit and will be implement most of your suggestions.

A couple of question though:

1. You mention that after making mod 5 the Sweep control will act more like a Manual control. How does this differ from the 'stock' Sweep control please?

2. After making the mods will an on/off/on range switch still work or should I switch it for on/on like you have?

Thanks again
 
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Chuck D. Bones

Circuit Wizard
A Phaser or Flanger is a comb filter. A comb filter has multiple notches in the frequency response. Normally, the notches move up and down to create the swirling effect. How fast they move is determined by the RATE control. How far they move is determined by the SWEEP control. In Manual mode, the notches are at a fixed set of frequencies. A Manual control lets you set the fixed notch frequencies. In the original version, setting the RANGE switch to the middle position turns the SWEEP control into a Manual control. In my modded version, the SWEEP control has a much broader range and at the bottom end of rotation reverts to a Manual control.

The ON-OFF-ON RANGE switch will still work with the modded version. I put in an ON-ON switch because I don't use Manual mode.
 
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Chuck D. Bones

Circuit Wizard
I'll admit I didn't offer much detail on how I did that. Here's the best pic I have showing the THROB LED wiring. The green wire is soldered to IC3-8. The other end of that wire is soldered to one side of R108 The other side of R108 is soldered to the THROB LED's anode lead. I put heat shrink over R108 and the LED lead after soldering them. The cathode lead of the THROB LED is connect to ground. The black wire in that same pic is the THROB LED's cathode connection. I soldered the black wire to ground at pin 1 of the RES pot. Any other ground point will also work. The THROB LED will have to be mounted in a holder since it's not supported by the leads.

Circulator THROB LED wiring.jpg
 

Guybrush

New member
Hi Chuck, sorry to bother you again.

Mod 7 suggests switching C4 for a 10uF cap. I ordered a 10uF box cap and it's absolutely enormous (about an inch and a quarter in width).

I'm clearly misunderstanding something. Would you be able to clarify what I need please?

Edit: Would this tant cap do the trick and if so, what way should it be orientated please?
 
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Chuck D. Bones

Circuit Wizard
I managed to typo mod 7 pretty badly. It's corrected now. If you want to go slower, change C14 to 10uF tantalum. Follow the board silkscreen for polarity.

Sorry about that.
 

sticky1138

Active member
Great suggestions. Any idea on where to start to improve the DEPTH range? Stock, the first 2/3 of the sweep is way too subtle, then the last 1/3 offers limited room to hone in a good sound.
 

Chuck D. Bones

Circuit Wizard
DEPTH is a blend control. If you want to expand the top end of rotation, try a C-taper pot. I probably should have used that because like you say, the bottom end of a blend is not all that interesting.
 

sticky1138

Active member
Thanks I'll try it out. I actually thought my build was defective because I was barely getting any effect, then I realized the depth needs to be cranked to hear the phasing.
 
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