Magnetic remote control switch circuit diagram b

Performance characteristics: This magnetically controlled automatic switching circuit is very simple, reliable in operation, low in failure rate, and very versatile. It can be used in
situations where the output is or can be converted into mechanical displacement.
    (2) Circuit schematic a is a magnetic control device using a Hall switch (SH). When the magnet is far away from the Hall switch circuit, due to the
forward fixed bias, the Hall switch circuit is turned on, its output is low potential, the thyristor is turned off, and the AC contactor KM is released. When the magnet moves
to the sensitive area of ​​the Hall switch, under the action of the reverse magnetic field, its output terminal suddenly rises to high level, VT is turned on through the diode VD, and KM
is attracted. Adjusting RP1 and RP2 can take into account both sensitivity and reliability (to prevent VT from being triggered accidentally).
    Figure 18-29b is a magnetic control device used in a reed switch (KP). When the magnet moves away from KR, the contacts of KR are opened, the transistor is cut off, and the relay
KD is released. When the magnet is close to KP, the contacts of KP are closed, the KD suction table, and the contacts of relay KD are connected in series in the control
circuit of the controlled electrical equipment. In this way, the movement of the magnet and its position determine the working status of the equipment. ．
    (3) Analysis For the circuit shown in circles 18-29, if the coil current of the relay KD is very small, or the voltage of the electrical equipment is very low and
the current is very small, then it can be directly connected in series with the reed switch and there is no need Other components. Reed switches generally have small contact capacity. To control large-capacity
loads, transistors, relays, contactors or thyristors must be used for voltage, current or rate amplification. Since the voltage required by the thyristor control electrode is very low and the current is very small, it is a better solution to connect
the reed switch to the control electrode circuit of the thyristor and the electrical equipment to the main circuit of the thyristor .