This 80's circuit has been winning. It is a 1 000 gain sample and hold circuit and an offset current setting. The configuration can be adapted to operate with modern equivalent components.
Using a sensitive reed relay (20 mA or less) it is possible to drive a high-power load from TTL...
We found this circuit in a 1998 documentation. The circuit can be made with 12 V, 6 V or even 5 V...
This circuit was found in Ferranti's 1974 transistor manual. The circuit is for non-critical...