When testing whether the trigger circuit would properly trigger a pulse from the Astro-Med, Inc. Grass Stimulator, we were able to get a reading on the oscilloscope. The frequency matched the 2 Hz output of the trigger circuit, and the amplitude of the output was 1 volt, which was what the stimulator was set to output.

This shows the successful triggering of the Grass Stimulator, which responded with a 1V pulse precisely matching its configured output setting upon receiving the 2 Hz square wave input from the trigger circuit.