This circuit from a 1966 General Electric manual makes use of an SCS. The time is given by the emitter capacitors of the unijunction transistor.
We found this circuit with an operational transconductance amplifier in the Motorola Linear...
We found this circuit in the 1994 Linear Applications Handbook by National Semiconductor. The...
In the figure we have a differentiator with the LM3900 transconductance amplifier. The circuit is...