This circuit generates short pulses. The transistor can be a 2N2222 or BC548 and the frequency is given by the resistors and the capacitor that can be changed.
This very low voltage regulator for 3 V input (2 batteries) was obtained in a documentation from...
This circuit consists of an adapter that allows the reading of low currents at various scales. A...
This circuit generates signals that can be adjusted in a small range around the frequency of the...