Trigger Converter

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z 1975, 2010, 2011 Nyle Steiner
They may not be used for profit, sale, or reproduced in any way without the express consent of Nyle Steiner

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This module produces an easy way to convert back and fort between S-Triggers(Switch Triggers) and Voltage-Triggers. Moog and Steiner at the least, used S-Triggers in their respective systems. Essentially, an S-Trigger is a switch which shorts the signal to ground. Whereas a voltage trigger is a signal which rises from ground when active.

Because the S-Trigger is typically an open collector which connects to ground when the transistor is on, there are some advantages, like the ability to simply connect them together in a multiple, in parallel without fear of shorting. The effect is to "OR" the triggers, that is, if any trigger is active, it overrides the other triggers which are not active. Depending on the circuit, an S-Trigger input might also be an output, the Steiner Voltage Sequencer is an example of this on the clock in/out jacks.

Of note, the Sequencer, Envelope Generators, Peak Selector, and Voltage Controlled Trigger Generator use S-Triggers. To use these modules, you need a convenient way to convert back and forth.

There are two configurations covered here.
  1. 8 S-Trig in/8 V-Trig out and 8 V-Trig in/8 S-Trig out
  2. 12 S-Trig in/12 V-Trig out and 4 V-Trig in/4 S-Trig out
#1 is meant for general use and it can be built into its own separate module. #2 is targeted for the Sequencer since it has many more S-Trig outputs than inputs.

NOTE: Some of the modules may have these built in as options depending on board space.

NOTE NOTE: Why not just put the conversion on all the PCBs? Without apology, I like S-Triggers and I wanted to keep the Steiner designs as true to the original schematics as possible. It's a bit selfish, but this project started out as a desire to finish the system I started as a teenager and I am personally building a standalone Steiner Synthasystem Modular "II".

As this project grew, I realized others won't want S-Triggers and I needed to provide a way to deal with this. A daughter board keeps the original module intact, but adds a seamless way for a user to hide the S-Triggers behind the module's panel. It's more cumbersome than just adding the pads on the PCB, but it was a compromise I could accept.

However, I think S-Triggers are just useful and I would recommend leaving the modules as the are using the S-Triggers and build this module separately and just convert when absolutely needed to interface with other modules.



This module has 16 inputs and 16 outputs configured in two ways:
  1. 8 S-Trig in/8 V-Trig out and 8 V-Trig in/8 S-Trig out
  2. 12 S-Trig in/12 V-Trig out and 4 V-Trig in/4 S-Trig out

This module has no knobs.


There are no switches on this module.

To use this module, plug an S-Trigger from a Steiner module which generates a trigger/gate into an S-Trigger input. Plug a patch cord into the appropriate V-Trigger output and hook to your favorite module.

The other way, connect a cable from a voltage trigger/gate source into a V-Trigger input and use a patch cord to plug the appropriate S-Trigger output into your Steiner module.

If you are using the Euro Panel, there are two multiples in the middle. You can use these like any multiple. For S-Triggers you can plug 3 S-Triggers into the multiple and get one output that is the "OR" of the three inputs. Or use it as usual to route the same signal to more than one place. DO NOT PLUG MORE THAN ONE V-TRIGGER SOURCE AT A TIME INTO A MULTIPLE. You can't combine V-Triggers that way. You need a CV mixer to do this.

You can be clever and use this module to "OR" V-Triggers by converting them to S-Triggers, "OR'ing" the S-Triggers and converting the resulting S-Trigger to a V-Trigger.

One of the more important differences between Bob Moog's use of S-Triggers and Nyle Steiner's use, is that Nyle recognized that there was no need to distinguish between triggers/gates, and other control, or audio voltages in a patch. Bob Moog ran all triggers/gates with special cables with Cinch, 2 prong jacks. Nyle used the same 1/8 inch jacks so the triggers could be used for different uses and combined into the audio or CV path than just a trigger or gate.

Component Selection

See the Component Notes page for more information.


Not critical.


There are none on the Trigger PCB.


Who put this here?


No ICs


Just small signal NPNs. I used the 2N5172s which worked fine.


Nothing special, 1N4148s are fine.


No pots.


No Trimmers.


For the panel I laid out, a good 3.5mm or 1/8 inch jack will work. I use the Switchcraft 42A Tini-Jax true 1/8 inch jack. These are switched jacks and they work with 1/8 inch plugs and 3.5 mm plugs.


No switches on this module.

Build Notes


I assume you know the basics of soldering. I like to insert the low lying parts first, like resistors, diodes, etc. After these, I install the IC sockets. Next capacitors, transistors, connectors. Use a good solder, either an organic flux, which you should wash regularly, or a no-wash flux.

Take a break every so often, wash off the flux if you are using a flux which required cleaning. Double and triple check orientations, pins, and solder joints.

Power Supply Regulation/Filtering

This PCB requires the Power/Regulation daughter board. There are two boards to allow this PCB to be parallel to the front panel which allows it to mount in shallow cabinets.

See this page for details on this module.

R2, R6, C4, and C8 are not used. The negative supply is not used and so the associated components may be omitted.

You only need to connect the GND, and +12 pins, 1 and 2.

Build this PCB first and get the regulators (if you use them) trimmed to no higher than +/-12 VDC. This module doesn't use the negative supply so the -10 volts is irrelevant.

Trigger PCB

Component Placement

You only need to put as many channels as you are going to use. The EG only needs 3 S-Trigger inputs, kind of a waste of board space, I know. That's why for every module except the Sequencer, I recommend just building a separate module and using patch cords.


This PCB has four holes to allow flexible mounting configurations. If you are using it behind another module's panel, Sequencer or EG, You can piggy back this board.

8X8 Version
This version was conceived to mount behind the Triple EG, or other standalone modules which use/produce S-Triggers.

It's use would be transparent and the connections are also described on the specific module's page. Mount this PCB on the back of the Power/Regulation PCB if present or on the module PCB, aligning the power input pads on the same side of the PCB. Connect the S-Trigger inputs on the PCB to S-Trigger outputs on the Converter PCB. Connect the front panel trigger input jacks to the corresponding V-Trigger inputs on this PCB. Now you can just plug a V-Trigger signal to the front panel seamlessly integrating it into your system.

Connect the module's S-Trigger outputs to S-Trigger inputs on the Converter PCB. Connect the corresponding V-Trigger outputs from the Converter PCB to the appropriate front panel jacks. You're done.

4X12 Version
This version is meant for the Sequencer. Mount it on the Sequencer logic PCB on the opposite side of the Power/Regulation PCB. Connect the power and then connect the Trigger Ins/Outs as described for the 8X8 PCB. More detail is on the Sequencer Page.


There is no calibration for this module.


This PCB will be included for modules which need it (eg: Sequencer). If you want to build it as a stand-alone, see Price List for pricing.

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PCB Values
PCB Names
Power Regulation Page


PCB Values
PCB Names

For both PCBs

Power Reg-Dist BOM