This circuit is from old documentation, but it can be implemented with more modern equivalent components. The transistor can be the TIP31 with a heatsink and the 1N4002 diodes.
This circuit, from ancient French documentation, produces a rectangular pulse from input pulses...
This timer for small intervals, but which can be increased with the increase of R1, was obtained in an...
Found in a 90s Radio Electronics, this circuit can supply currents of a few amps, according to the power...