Abstract: An electronic device comprises an arrangement which makes it possible to power a transmitter in self-contained fashion from a pick-up without any other power source. The device comprises at least one transistor and a transformer having a high turns ratio. The primary windings are connected in series with controlled electrodes of the transistor. The secondary windings of the transformer act on the controlling electrode of the transistor and the very low voltage is applied across the primary windings and the controlled electrodes. Voltages of a few mV which are thus applied result in the appearance of voltage pulses of a usable magnitude at the terminals of the secondary winding which may be accumulated in a capacitor to feed the transmitter intermittently. This device can be used in a self-contained detector-transmitter for use as a remote fire alarm.