SDIY Building Blocks

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Gates And Triggers ​

What It Does

In synthesizers gates and triggers are essential ways to start things.

Gate vs trigger ​

Look at the simulation below if you are unsure about the difference between a gate and a trigger.

  • Please hold the switch of the gate. Notice the LED keeps being lid.
  • Please hold the switch of the trigger. Notice the LED only give a very short burst.
  • Gates are used when the duration of the input signal is part of how you control something.
  • Triggers are used when the duration of the input signal is not allowed to influence anything.

Gate to trigger ​

With comparator ​

I realy like to use op-amps for creating gates to triggers, because they are flexible, precise and clean.

  • Notice the op-amp is in comparator configuration.
  • Please play with the capacitor value and voltage divider.

With transistor ​

With Schmitt triggers ​

  • Notice I used two inverting Schmitt triggers in series.
  • Remove the last Schmitt trigger to get the inverted signal. Can be useful to reset someting.
  • Lookup the thresshold levels of your Schmitt trigger in its datasheet.

Gate delay ​

  • Notice the output gate is just a little bit later that the input.
  • Control this delay with the variable resistor.

Trigger to gate ​

If you want to reverse engineer your triggers to gates. Can be useful if some external triggers are just too short for your main circuit.