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Circuitbenders Forum => Drum machines => Circuitbending discussion => Korg => Topic started by: selfpreservation on May 31, 2011, 08:29:44 PM

Title: korg rhythm 55 trigger ins
Post by: selfpreservation on May 31, 2011, 08:29:44 PM: ive got one of these anyone done trig ins ? i take it it needs neg trigger so needs inverted with a tranny or something not sure how to go about it myself any ideas ?
Title: Re: korg rhythm trigger ins
Post by: Circuitbenders on May 31, 2011, 09:34:18 PM: korg rhythm what?
Title: Re: korg rhythm 55 trigger ins
Post by: selfpreservation on May 31, 2011, 09:46:33 PM: soz kr55 8)
Title: Re: korg rhythm 55 trigger ins
Post by: Circuitbenders on June 01, 2011, 12:05:53 PM: i guess it'll be negative going trigger pulses as most Korgs are. Remember that a negative going pulse doesn't mean its an actual negative voltage. Instead it means that the trigger input will be held at +5v and it'll trigger on the downward slope of a short to ground.

You need a circuit like this http://www.kpsec.freeuk.com/trancirc.htm#inverter (http://www.kpsec.freeuk.com/trancirc.htm#inverter) where the transistor is triggered by the normal +5v pulse, or assuming you need multiple triggers you can probably use a 40106 hex inverter or similar.
Title: Re: korg rhythm 55 trigger ins
Post by: selfpreservation on June 01, 2011, 07:37:47 PM: if i use the shmitt triggers do i still need resistors?
heres a section from the manual the sounds are on there db sd hh1 hh2 ect , they all seem to share a common 5v rail is this an indicacation of it being -ve trigger ? and is this a good point to interrupt with my trig ins? if so where ie at what point ?
(http://i1139.photobucket.com/albums/n551/ciaranbyrne606/55.jpg)

i havent actually recieved the thing yet so i havent had a play yet

cheers ciaran
Title: Re: korg rhythm 55 trigger ins
Post by: Circuitbenders on June 02, 2011, 01:29:15 AM: If you look at the rest of the service manual schematics theres individual diagrams for the synth circuit of each sound. The trigger inputs will probably be the start of each circuit i.e where it says the name of the sound on the left hand side of the page. You could really do with looking at it on a scope to see exactly whats happening there though.

i don't think you'll need the resistor on the input to the 40106 although i could be wrong.
Title: Re: korg rhythm 55 trigger ins
Post by: selfpreservation on June 11, 2011, 08:41:27 PM: Quote from: Circuitbenders on June 02, 2011, 01:29:15 AM
If you look at the rest of the service manual schematics theres individual diagrams for the synth circuit of each sound. The trigger inputs will probably be the start of each circuit i.e where it says the name of the sound on the left hand side of the page. You could really do with looking at it on a scope to see exactly whats happening there though.

i don't think you'll need the resistor on the input to the 40106 although i could be wrong.
so do you think i could get an engineers at work midi trig like you used on the bra and take the outputs straight into shmitt trigger chip and take the outputs ot the shmitt and wire them to the synth section ?
Title: Re: korg rhythm 55 trigger ins
Post by: SynthularModulus on December 09, 2019, 07:06:03 PM: Any luck with your Trigger in mods? I am interested in doing this with KR55, and just wondering if you figured it out. How about other mods for the KR55? I've seen individual out mods, and clock in mods online. I'm considering doing those as well....