Timer circuit for a stroboscope

Claim 1

A timer circuit for triggering a stroboscope at successively longer intervals following the occurrence of preselected repetitively occurring events comprising a first 555 timer, an RC circuit, means for charging the capacitor of the RC circuit through the resistance thereof thereby to generate a ramp voltage across the capacitor, said capacitor being connected to said timer to be periodically discharged thereby so that the ramp voltage is generated repetitively, the resistance in said RC circuit being variable so that the repetition rate of the ramp voltage varies in response to changes of the resistance, an amplifier having an input connected to the capacitor of said RC circuit for amplifying the ramp voltage, said amplifier including feedback and bias control means for holding the instantaneous value of the ramp voltage at the center of the ramp approximately at a constant, preselected value, a second 555 timer, variable means for applying a selectable fraction in amplitude of the ramp voltage from said amplifier to the control input of said second timer, means for applying a trigger signal to said second timer synchronously with the preselected repetitively occurring events, and output means for applying the output signals of said second timer to a device such as a stroboscope to be periodically triggered.