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© 2016 Burr Settles (LICENSE)


GAIUS is based on the dan armstrong green ringer with an added NULL control to vary the intensity of the effect.

When playing a single note, it doubles the tone one octave up; but if playing two notes, it will produce sum and different tones like a ring modulator. Depending on the interval between the two notes, the additional tones will be harmonically related to the original notes (such as sub octaves) or dissonant. The added NULL pot varies the intensity of the effect: fully clockwise is the stock circuit; dialing it back will make the circuit less symmetrical and dampen the effect.


  • The NULL pot is layed out as a trimmer for flexibility: you can also to wire up an off-board pot, or just use a trimmer to "set it and forget it." You could also use a 500kC pot for a wider intensity range, but personally I think the 100kB is enough.
  • If you want to omit the NULL control altogether, simply jumper pins 2 and 3.
  • For the clearest octave effect, match diodes D2-D3 as closely as possible for forward voltage. You should also try to match resistors R6-R7 (10k) and R10-R11 (22k), although if you use 1% metal film they're probably close enough anyway.

bill of materials

Qty Parts Value
3 C1, C3, C4 47n film
1 C2 100u electrolytic
1 C5 100n film
1 D1 1N5817
2 D2, D3 1N914
2 Q1, Q3 2N5088 (or 2N5089)
1 Q2 2N3906 (or other PNP)
1 R1 1M
1 R2 470k
1 R3 160k
1 R4 18k
1 R5 6k2
3 R6, R7, R12 10k
2 R8, R9 68k
2 R10, R11 22k
1 R13 47k
1 NULL pot 100kB (or 500kC)




1.3" x 1.28" (1590a)


build pic


18 June 2016