Supply circuit in a communication system of a protective head covering

A supply circuit 28 in a communication system of a protective head covering (fig. 1) supplies the communication system from an energy source 30, 32 associated with the protective head covering and comprises a step-up converter 44. A voltage limiting facility 60 may be arranged on the output side, and may comprise at least one Zener diode 62. At least one inverse diode 56 may be arranged on the input side. The step-up converter may comprise an inductive coil 46 (L1), an electronic switching element (SW), such as a MOSFET 48, a capacitor 50 (C1), and a free-wheeling diode 52 (D1). The switching element may be connected to a centre tap between the coil and the free-wheeling diode. The supply circuit may comprise a plurality of individually resistively protected tap points 54, 66 for tapping a respective output voltage. The supply circuit may be embedded in a casting medium for encapsulation. The protective head covering may be a face or full-face mask , a protective respiratory mask, helmet or escape hood, such as used by the fire brigade.