Small relays are with five-pin, five-pin relays are used with two legs on one side and one foot in the middle. Generally, the middle of the three-pin side is the common terminal of the output contact, and the other two pins are the coil. One end of the two pins is output contact for normally open and normally closed, and common terminal is normally open, and common terminal block normally closed, can test by a multimeter to know!
Relay is an electrical control device that causes a predetermined step change of the controlled quantity in the electrical output circuit when the change of the input quantity (excitation quantity) meets the specified requirements.It has interaction between control system (also known as input loop) and controlled system (also known as output loop).It is usually used in automatic control circuits, it is actually a kind of "automatic switch" that useing small current to control the operation of large current.Therefore in the circuit plays the role of automatic regulation, safety protection, conversion circuit.
6 Layers Green PCB Board
The 4 diodes connected in sequence on PCB circuit board are the rectifier circuit.
Bridge rectifier circuit is one of the most used rectifier circuits.This kind of circuit, as long as two diode ports are added to connect into the "bridge" structure, has the advantage of full wave rectifier circuit, and at the same time overcomes its disadvantage to some extent.
In the positive half week of u2, D1 and D3 are switched on, and D2 and D4 are closed. The current goes from the upper end of TR to RL to D3 back to the lower end of TR, and half of wave rectification voltage is obtained on the load of RL.
In the negative half week of u2, D1 and D3 cut off, and D2 and D4 are switched on. The current goes from the lower end of Tr to RL and D4 back to the upper end of Tr, and half of wave rectification voltage is obtained on the load of RL.
In this way, a voltage waveform is obtained on the load RL, which is the same as the full wave rectification, and its current calculation is the same as the full wave rectification, i.e
UL = 0.9 U2
IL = 0.9 U2 / RL
The average current flowing through each diode is
ID=IL / 2=0.45 U2 / RL