Found in a1969’s neon lamp documentation, this circuit uses a high voltage transistor. The output currents reach 100 mA.
This battery-powered micropower supply was shown in Radio Electronics magazine in 1991. The...
Found in a 1965 Electronic Design, this circuit can be made with modern equivalent transistors. The...
In this circuit, the current in solenoid X1 can be adjusted and its intensity measured to the...