At the time, I was very surprised by the capacitive three. I was sure that it was possible to build a generator on one transistor only with a transformer. It turned out that it is not.
And what is the minimum number of transistors necessary for RS-flip-flop? I did not even think about this question. I was sure two. And recently it turned out that
one is enough .
An external clock generator (from 200 to 500 kHz, TTL levels) is required for the trigger to work. It can be common to all triggers in the scheme. To translate the trigger into the state of a logical unit, you need to briefly apply the supply voltage through a resistor to the capacitor C2. The LED, lit and continued to glow and after the cessation of the supply voltage, will indicate the successful change of one steady state to another by a trigger. To return a trigger to the state of logical zero, either the same capacitor must be short-circuited briefly, or the clocking of pulses is stopped momentarily. The LED will turn off, and after, respectively, removing the jumper from the capacitor or returning the clock signal will not turn on again.
Trigger output signals are unusual and uncomfortable. Logical zero corresponds to the supply voltage, unit - the clock signal. The only thing left is to invent a time machine for transmitting at least just information. This circuit would be very useful in the fifties, when transistors were much more expensive than capacitors and resistors. But then for some reason nobody invented it.