CYGN-A

[Greg]

Yes, I will need that. Thank you Brian. I agree Steve, that is a beautiful thing... but where's the rest of it? The KQO I remember had a flyback that looked similar to the one seen in the spiral circuit I built in the early 1990s from 2N2222 BJTs and the >1 Henry ferrite cup core from Bell Labs, first mentioned here:

https://www.photonlexicon.com/forums...3-CYGN-B/page8

The FXCY KQO in the photo looks like something perhaps is being over driven, and the flyback curve is hiding in a dot, waiting to unfold from somewhere. Investigation continues.

[laserist]

The retrace you remember was a product of the G-124s scan-set and PDM scan amps. A signal that comes to a screeching halt on an oscilloscope behaves much differently on the dome. Wait until you see the signals after they get past the clippers...

[Greg]

That's good to know, as it means that this circuit is performing to spec and further investigation is unnecessary. The previously posted photo has the signal passed through the clippers, though nothing is being clipped due to pads attenuating the gain from the 0 and 90 degree outputs. The clippers appear to be amplifiers that simply clip at a level close to the supply rails.

[laserist]

I have a memory of it not really showing up on an oscilloscope, but when the KQO signals are run through the dual pot the out of balance signals into the clippers produced a very cool symmetry effect within the body of the KQO image without effecting the outer edge. As the gain of one signal increased and the other decreased as the dial was turned off of 5 - one axis became elliptical within the body of the image. Perhaps it was a tiny phase shift writ large by the G-124/PDM scan amps...

[Greg]

I have a memory of it not really showing up on an oscilloscope, but when the KQO signals are run through the dual pot the out of balance signals into the clippers produced a very cool symmetry effect within the body of the KQO image without effecting the outer edge. As the gain of one signal increased and the other decreased as the dial was turned off of 5 - one axis became elliptical within the body of the image. Perhaps it was a tiny phase shift writ large by the G-124/PDM scan amps...

A fortunate gem of a recollection, that. The signal does not look like the image. THAT is the secret of the KQO. I wouldn't have guessed it, but there it is, and a beautiful thing too.

I think this was used in Mars in Starship.

It seems to me that Keyed Resonance Oscillator (since Q is resonance) is more descriptive than Keyed Quadrature Oscillator, as the 6b is full of quadrature oscillators. It even looks like a big letter Q.

This creates a problem in capturing a KQO. Perhaps someone who knows more about GS devices than I do would comment on the feasibility of obtaining a position signal from the unused wires, since these are running in open loop.

[Greg]

I meant GS100PD, not GS120PD.

[mixedgas]

See attached for a very sniped CX-660 position input schematic and one from a Tropel.

I prefer the one with inductors.

Care and Feeding part one page 10 has how to wire galvos without AGC feedback circuit, tie pin 4 to pin 12 in that case.

Steve

[laserist]

There are two ways to approach this. One is to record the feedback signals from your 100PDs. The other is to build a circuit that makes modern scanners behave like non feedback scanners when you want. You could even play the amount of "ringing" on your dogloids and whatnot.

[Greg]

There are two ways to approach this. One is to record the feedback signals from your 100PDs. The other is to build a circuit that makes modern scanners behave like non feedback scanners when you want. You could even play the amount of "ringing" on your dogloids and whatnot.

I hadn't thought of that. Following that idea, a circuit that imposes the desired overshoot, ringing, phase shift, distortion, etc. under user set depth control (like effects pedals), and without moving parts, and passes the signal through as +-10V which can go to existing summing amps. Either of these approaches however, is outside my range of ability to design.

[laserist]

Two op-amps hooked up as differentiators would be a good start, but I'd likely just do it with a micro-controller sampling the inputs and modifying to output. It wouldn't be KQO but you could get 98% there by ramp shaping spirals non symmetrically.