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Serge Phaser CGS90 Current Draw
MUFF WIGGLER Forum Index -> Music Tech DIY  
Author Serge Phaser CGS90 Current Draw
Hello All.
Anyone with the Ken Stone CGS90 Phaser have an idea what the current draw is? I'm seeing 50mA +15vdc and 50mA -15vdc.
Problem is, the CA3046 gets hot as heck. Iv'e breadboarded this portion of the circuit using BC550s and the 123 transistor in the diff pair gets very hot. The 220R resistors get pretty hot too. Can anyone describe how the "Cascaded Diff Pair" works as a vactrol/ LED driver? I looked around and have found nothing similar.

You have a build problem
Is the 220R hot in the CGS90 board, or just the breadboarded version? Do you have the CA3046 socketed, so you can test the circuit without it?
50mA on the postive rail could be normal. I've build this once but only on stripboard with my own Vactrols (LDR+LED rolled at home) I made several modifications to the LED Driver circuit that reduced the current consumption more than a half...

Maybe if you don't have a etched PCB already, perhaps try out the LED Driver from Scott Stites Multiphase Project or Mutant Vactrol Filter... Really low parts count a few resistors, 2 trannies and a trimmer... Got my Vactrol BPF working great with only 2-3mA max. current...
Also in his documentation there is a fruther Option with an OP amp for bipolar CV Signals...

P.S. as you have this on breadboard... make sure you use the same Pins as in the schematic or at least take care that the Substrate (pin13 or 14, don't know exactly, just look at the datasheet) of the Array is at the most negative voltage...

P.P.S. Just had a look at my printed schematics if i made some notes... Looks like i had abandoned the original LED Driver and replaced it with one the above mentioned, but i'm too lazy right now to pull it out of it'S case and see if i really did or this was just an idea i had in mind...
Thanks for the replies.
Yes, the 220Rs get hot in both the CGS pcb and the breadboard version. The 3046 is socketed. I swapped discrete transistors into the socket and same results. If 50mA +- is what its supposed to be, then so be it. Racked and done. Onto the VCS next! Curious about the cascaded differential pair, as the Jurgen Haible Tau Phaser converts the modulation waveform to a hypertriangle which is preferred by some for phaser and flanger sweeps.
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