Clocking the Korg SQ 10 - S triggers

I've been trying to clock or sync the Korg sq10 sequencer over the years with mixed success.
It's one of the limitations of this piece of kit.

Back in 1978 when this was made, there was no real industry standard such as MIDI. The different manufacturers went their own ways. Korg did provide a input jack for single stepping the sequencer. This is the best way to syncronize the SQ-10.

The clock/step input is a +5V trigger to ground.
Normally, the voltage is "high" . When a note is played, the trigger is shorted to ground.
This is also called an S-trigger, "short circuit trigger", or "negative trigger".
S-triggers are used by Moog, Korg and Yamaha synthesizers

(As a side note, the other form of trigger is a V-trigger. It's the reverse of an S-trigger, as it's a positive trigger. That is, normally the voltage is low (around 0 v) and at trigger produces a fixed positive voltage)

If you are trying to sync it up to other gear such as a roland Drum machine which uses sync 24 (also referred to as DIN), you will need a good clock divider, and probably some logic gates for it to work correctly.

Old Korg Drums seem to be the traditional way to clock the SQ10
The Korg Rhythm 55B (KR 55) clocks the sq10 perfectly.

The 55B manual, says you can choose the type of trigger with the switch on the left.

It has just the right outputs which match the SQ10's inputs
It looks like this drum was made for the vintage MS series of Korg synths.

 For this to work, there are only 2 settings on the SQ 10 you should use:

Sadly, the KR 55 as no sync or clock input. I would love to add midi sync.
The KR-55 runs at 8ppqn so a clock divider is required if you want to sync it to midi or sync24. 
The clock output on most Kenton midi to cv converters is ideal for this (divide by 3).

Other Korg drums that should be useful (Though I haven't tested them)include:
Korg KPR-77
Korg DDM 110 (Super Drums)
Korg DDM 220
Korg DDD 1

+ Korg Drum Machine Timeline
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Roland Drums

*** A Roland TR 606 drum will also step the sequencer. 
    Use the LT & HT trigger outs. This is a really cool way to 
    trigger the SQ10. turning on and off the toms will
    stop/start the Sq10.

The Roland CR 78 also sends a suitable trigger pulse.

This is the setting I used.

However, if you wish to sync this drum to something like midi, use the Future Retro Swynx. You can also program new patterns and you have DIN Sync.

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As the step input is a S-trigger, I decided to try a Moog Mother.
And guess what, it works.

The Moog Mother is the perfect midi clock to S-trigger converter.
(and it does a few more things besides)

plug the gate out of the M32 into the step in of the Korg sq10 
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For the Korg SQ-1 to sync the SQ10,  you need to change the SQ-1's GATE OUT polarity from positive (factory preset) to “-” (negative).

"While holding down the SQ-1's START/STOP button, turn the power on (the unit starts up in global parameter setting mode).
• Press the SQ-1's MODE/CLEAR button to make the button go dark. (This alternates between un-lit and lit each time you press the button: “-” when un-lit, “+” when lit.)
• Press the SQ-1's power button to save the setting."    (Korg Manual)

Sadly, the S-trigger uses up one of the gate outputs, not the sync out.

  Links
+ Modular Clocks - Analog, MIDI , PPQN
+ V-trig to S-trig converter