This simple timer with unijunction transistor was found in an old American technical documentation. We can use 2N2646 for the unijunction and BC548 for the transistor.
In the figure we have the way to trigger a 7555 CMOS monostable with a positive pulse. The time...
This circuit is from a 1968 documentation. It generates a non-symmetrical signal with the waveform...
This circuit is from the manual of the used operational amplifier itself. The same setting can be...