CLUB OF CAR FANS
WHAT A DIODE CAN
The main feature of the diode - to conduct current in one direction - can be used not only to rectify the current
For example, in old cars where there was no glass washer, it is possible to automatically turn on the "wipers" when the pump is running, by connecting the pump motor M1, as shown in the diagram (Fig. 1). When the Bk1 button is released, the pump will turn off, and the wiper blades will stop only after the cycle has been completed and laid back. Thanks to the diode, the pump will not turn on during the operation of the wiper if the standard switch of the last VK2 is closed.
A few more examples. The B117 ignition coil does not have an additional resistor. Accordingly, the Zhiguli starter does not have additional contacts in the traction relay. And if it was required to install a B115 coil in the Zhiguli? A diode connected as shown in fig. 2, will provide voltage directly to the primary winding during operation of the starter.
Only one diode added to the standard scheme for switching on sound signals and high beam headlamps (Fig. 3) will automatically turn on the headlights when an audible signal is supplied, but will not allow the signal to sound when the headlights are turned on.
Now we turn to another, less well-known property of the diode. It consists in the fact that when the current flows through it in the forward direction, the voltage drop across the diode is almost independent of the magnitude of this current and is 0.4 V for a germanium device and 0.7 V for silicon. Therefore, having included the diode in the power supply circuit of the voltage regulator Я112 installed on modern generators (Fig. 4), we will increase the voltage of the generator by the above value, which is useful in winter. In summer, the VK switch will exclude the influence of the diode on the generator. Suitable, for example, germanium diodes D304, D305. Silicon significantly more: D214, D215, D231, D232, D242, D243, D245, D246, D247, KD202, KD203, KD213. And in the diagram in fig. 3 suitable and low-power, for example KD209.
Fig. 1. Connection diagram of the washer motor: M1 - washer motor; M2 - wiper motor; VK1 - washer power button; VK2 - wiper switch; VD - diode KD202.
Fig. 2. The circuit for switching on the B115 coil instead of the B117: P - circuit breaker; VD - diode KD202R.