July 28, 2021 at 12:49 pm #19972
Just finished the first couple parts of a combo build. I built a Trotsky/Electra distortion with multiple modifications. I first breadboarded it and then built the circuit on veroboard and it ended up an epic fail. I don’t know if my layout design was to blame, bad soldering (it was difficult not getting solder bridges in some places) or something else. After a couple of hours of trying to diagnose what was wrong, I gave up because I had a spare GBOF laying around and knew that there was a Trotsky layout on the Guides page for the board that I could utilize as a known working build. My concept for the circuit in schematic form.
I then made the few modifications to the standard Trotsky layout to follow the schematic as below.
I had tested all the mods on the breadboard beforehand so I know they worked with the circuit – that is all the switches and pots including the Rototone. Since I had discovered and proven by voltage measurements to the collector side of the circuit that adding resistance along the 9V power supply, I added the Turbo switch for instant additional gain.
The soldered up boards and circuit for placement inside the enclosure – everything had been placed in the enclosure to measure all the wire lengths needed for connecting the board with the 2 pots and 4 switches. This crazy looking mess was attached to the breadboard for power and input/output and functions as it should.
Next I will add other boards to the enclosure and wire them in. I already have the enclosure drilled so it is just a matter of wiring things up and completing the enclosure as I already have my graphics finished and need to transfer them to the box.
While on the subject of Electra type distortions, below are GBOF layouts of Electra type circuits other than the Trotsky distortion. These are easy to build, pretty decent sounding distortions.
Standard Simple Electra:
Badass Electra that can be found on the internet (courtesy of Joe Gore):
The finished project will be posted later on this forum, hopefully in a couple of weeks or less.July 28, 2021 at 1:26 pm #19973
Forgot to add the picture of the bare, drilled enclosure.July 28, 2021 at 4:12 pm #19974
Clever design! I don’t see the ROTOTONE contents in the schematic.July 29, 2021 at 12:35 pm #19979
The Rototone is the “switch” with 4 slections after the 1u (100n) output cap and prior to the the symmetric clipping diode “pairs” in the schematic. The biggest difficulty in this build was soldering all of the switches and pots to the small GBOF board that provides very little room for error between solder pads for all the input and output wires. Very tight fit, but it works. The GBOF is about half the size of the veroboard piece that I initially attempted to build the circuit on. Now I just have to finish connecting another board to a couple of pots and switch, and then wire up the power and input/output jacks.July 29, 2021 at 1:36 pm #19980
What are the four selections of the ROTOTONE? Are they diodes, caps, etc?July 29, 2021 at 2:07 pm #19981
Diode clipping pairs. Another switch located in the path after the Rototone adds a third diode in parallel with any of the 4 selected diode pairs for asymmetric clipping.July 29, 2021 at 2:45 pm #19982
Thanks! I wondered what options you had there.July 29, 2021 at 4:38 pm #19985
Power Supply Resistors: Select Standard Trotsky (3.3K + 50K Pot) or Turbo mode (47K + 50K Pot) which increases overall voltage to collector side of circuit and therefore greater gain/distortion.
Input Caps: Select Trotsky (0.047u) or Electra (0.1u)
Rototone: Select 1 type of 4 paired clipping diodes
On/Off Switch: Deselect or Select extra clipping diode for asymmetric clipping. I was going to Rototone this as well for 16 types of clipping, but there was no room to get the extra Rototone into the enclosure.July 30, 2021 at 12:43 pm #19989BarryKeymaster
Love it. Thanks for the Images and schematic.July 30, 2021 at 4:56 pm #19991ChuckParticipant
And here I was wondering what to do with my last couple of GBOFs! Wow!
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