We found this circuit in an American publication from the 90s. It generates pulses that can be modulated in amplitude. The supply can be done by voltages from 5 to 12 V and the frequency depends on C1 and C2.
This circuit is from an English magazine of 1977. The circuit is still current, just using a TIP41...
With a touch of the push button the lamp is switched on. A new touch and the lamp go out, in this...
The transistor for this flashlight brightness control may be the BD135. The circuit is from 1978...