Monostable multivibrator

Claim 1

A monostable multivibrator circuit comprising: a semiconductor device having a first semiconductor region of one conductivity type, a second semiconductor region of the opposite conductivity type adjacent said first region with a first semiconductor junction therebetween, a third semiconductor region of the same conductivity type of said first region adjacent said second region with a second semiconductor junction therebetween, first, second and third terminals coupled to said first, second and third regions, respectively; a fourth terminal connected to said semiconductor device and having at least a portion thereof located adjacent to said first region at a position which is spaced from the said first terminal, and an insulating layer separating said fourth terminal from said first region, an emitter grounded current amplification of said device being adjustable from a relatively high value to a relatively low value by changing a voltage on said fourth terminal, means for applying a trigger signal to the second terminal of said semiconductor device, a circuit branch containing a capacitor, which branch connects the third and fourth terminals, a predetermined bias being applied to said fourth terminal which is chosen such that in the absence of the trigger signal and in a steady state condition said current amplification is substantially at said relatively low value, means for applying a power source across said first and third terminals of said device, and second means coupled to said second terminal for biasing said device into a conducting state when said current amplification is substantially at said relatively high value.