Hohner 80 drum machine, where trigger inputs set? help

Hello folks,
I bought a drum machine (Hohner Rhythm 80). I wanted to add individual trigger inputs, the trigger points are (schematically) marked in red in the picture, there are approx. 1.8V there (measured with a multimeter) or approx. 4.2V measured with an oscilloscope if the snare, conga etc. is internally triggered , I don’t have a square there (at the cathode) but a mixture of sine and saw as can be seen in the picture! However, if I connect it to the anode of the diode, I get a clean square on the oscilloscope, which certainly makes more sense, doesn’t it?
On the website…


…is advertised for a midi module which, however, shows the trigger points at the red marked points (at the cathode) as on the schematic!
Who has experience with should things, where should I connect my trigger inputs?
The Hohner has a voltage supply for the semiconductors between 5 - 9 volts!

Incidentally, I used an “analog output” circuit for triggering (see picture), this seems to work, but I’m looking for a PURE trigger circuit for the drums!
Does anyone know a circuit diagram that I can use for my purposes, would like to work without a gate to trigger converter!

I am sorry to inform you you ARE working with a gate to trigger converter, or in fact converters, one on each input. The shape you see on the scope is a trigger signal derived from the square wave (gate) going into the diode. The capacitors and resistors to the right shape it into that trigger shape.

My circuit diagram is something that takes a possibly small or misshaped gate signal, either on the input jack or created with the push button, and conditions it to a good square 12 V gate. The gate can be any width and if it’s narrow enough it can be regarded as a trigger. In any case, going into the diode anode, it’d get converted to a trigger by the Hohner circuit. The 12 V gate level may be, in fact from what you say I’d think it almost certainly would be, larger than you want. But it could be attenuated, or use a smaller supply voltage.

There may be some good reason to inject a trigger signal after the diodes but I don’t know what it would be. It seems especially odd for the cowbell. There you see the anodes of two diodes are connected together, so two circuit sections are triggered at the same time. If you’re injecting a trigger after the diode you’d have to inject it in two places (the two bottommost red marks) at the same time. I guess tubbutec calls that a feature not a bug: “This is because the Cow Bell consists of two separate sounds. With uniPulse you can trigger these sounds individually or simultaneously depending on your configuration settings in the uniPulse configurator.”. Also the bongos, claves, and cowbell have some additional input shaping in the form of a capacitor and resistor before the diode, which would be ineffective if the trigger were injected after the diode.

So I don’t know tubbutec’s logic but it seems to me if you’re not using the original trigger points (the inputs on the left) you need a good reason, and tubbutec doesn’t seem to give a reason.

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Thank you “Analog-Output” for your feedback!

Connected to the ANODE with a trigger or with the pure gate (5V) I do not trigger a sound on the Hohner!
I then simply tried it from somewhere with a voltage of 6V and 9V and lo and behold, the tones can be elicited from the Hohner at the anode!
I don’t understand why this is the case, I think the Hohner would only have to be triggered internally with 5V, since many Hc74… are installed, all with an operating voltage of 5V, but there is no internal 6-9V ready to trigger placed !?
I’m afraid to trigger externally at the anode with 6V or 9V, I think the IC’s in the Hohner could break as a result, but the danger is there???

With the “Schmitz trigger” it works satisfactorily to very well (connected to the cathode)!
However, with the “High Hat” I always get a “cracking/knocking” when triggering next to the usual noise, as if an attack is too sharp, I can’t get it away!

The cymbal always has a “tom” noise, sounds almost like a snare! Here, too, the “knock/tom noise” should be eliminated, then everything would be fine!

By the way, I get my gate from “LMNC 8 track sequencer” with the mod from “Analog Output”, this sequencer only sends 5V to my trigger circuit!
When the “Bass Drum” and Bongo are triggered, the CowBell sounds very, very quietly!

Does anyone have an idea what to do?