The safety device that signals the limit of the battery, must have for every modeller. The scheme of such a simple electronic device — figure 1. The unit is connected to the battery pack and press the button S2. If the supply voltage exceeds 10 V, relay K1. But as soon as this value is reduced to 10 volts, Zener diode is closed and relay K1 is de-energized. Contact K1.1 includes a signal lamp H1.
Figure 2 shows a diagram of a similar device with a lock through make contact K1. 1.
Details: relay RES-10 (RS4 passport.524.304, coil impedance 45 Ohms), lamp warning of any type on 10-12 V.
The resistance of the resistor R1 is selected in the process of adjustment in the range of 65-100 Ohms.
L. KATIN, engineer