receiver power from engine battery - in model boats

One of the draw-backs in model boats (and other models as well) is that most of them need two batteries: one for the receiver and servos, and the other for driving the engine. The circuit suggested here removes this deficiency by making it possible for the receiver and servos to be powered by the engine battery. receiver power from engine battery receiver power from engine battery elektor february 1985 The circuit consists of two distinct parts: a stabilizer to provide the nominal 4.8 V for the receiver, and a comparator that operates a relay when the engine supply drops below a pre-determined value. It is not always necessary to build both parts of the circuit: each can function independently. Stabilizer As the nominal battery voltage, Ub, is 6 V and the receiver needs 4.8 V, the stabilizer must be able to work from just 1.2 V. Care- fully chosen components and cunning configuration ensure that it does. Zener diode D3 is driven by current source T1, and sets the base voltage of T...