EH Microsynth - further idea

[StephenGiles]

It occurred to me yesterday morning when throwing a ball for Bonzo, our 3 legged dog, that if the Microsynth start/stop frequency CV buffer output could be clamped (correct word?) by a CV extracted from the peak voltage equivalent to the strength of notes played, it could achieve a peak following option for the leading edge of notes played. Bonzo is actually laying on the floor next to my left leg as I type!

So how can this be achieved? Don't forget there is a plethora of control circuitry in the Microsynth which could be tapped and adapted for an "Adaptive Peak Clamp" - I like that

Could be some mileage in this
http://www.freepatentsonline.com/5502746.pdf

I'm taking some Aphex Patents for poolside reading in Spain this week - might throw up something - unless I eat something dodgy first

[Earthscum]

try looking up "Peak detect and Hold" circuits. I kinda remember seeing an EDN article on it, but apparently I didn't copy that one to my data stash.

I think you could use something similar to what controls a noise gate, but I'm imagining the 'reset' triggering to be a pain.

[StephenGiles]

No, looking at the Stop/Start envelope generator again, together with the CA3094 voltage follower which feeds the VCF, perhaps it looks similar in principle to the Space Drum wizardry, where the initial frequency of the sound is determined by how hard the drum pad is struck - which in circuit terms, determines the amount of current fed into the CA3094.

So I think it might be worth trying this (looking at the 12/12/78 circuits):

The trigger signal (point 7) which is fed to both the 2N5087 (switch?) and to pin 5 of IC A13 - the CA3094, via the 6v8 zener and 2k2/22m network should be disconnected from the 6v8 zener and replaced by a voltage source which varies between -8v  (when the unit is at rest) and +8v (when energised), being proportional to the strength of notes played.

The voltage at the output of pin 7 of peak follower IC 5b looks promising, as it varies from 0v at rest down to -7v when energised. This could be level shifted to provide the correct voltage range using a spare half of an opamp. If there are none spare, perhaps it can be done passively?

Food for thought, I don't have a Microsynth so perhaps somebody would like to experiment.

[StephenGiles]

Having read this again, I've changed it slightly:

The trigger signal (point 7) which is fed to both the 2N5087 (used as a switch?) and to pin 5 of IC A13 - the CA3094, via the 6v8 zener and 2k2/22m network should be disconnected from the 6v8 zener and replaced by a voltage source which varies between -8v  (when the unit is at rest) and up to +8v (when energised), being proportional to the strength of notes played.

The voltage at the output of pin 7 of peak follower IC 5b looks promising, as it varies from 0v at rest down to -7v when energised. This could be level shifted to provide the correct voltage range using a spare half of an opamp if there is one, otherwise  - perhaps it can be done passively?

It really is a nusiance not having my old Microsoft board, which was scrapped long ago. Maybe I'll breadboard this when we get back from Spain next week.

[StephenGiles]

Only one half of IC A9 seems to be used as the Stop Frequency buffer - so there you go

[StephenGiles]

How about putting an MN 3005 in there to delay the filter trigger.

[StephenGiles]

Too difficult??

[StephenGiles]

No offers of a solution? I don't believe it