12V Relay Switch Control

• Case Description: "Light control Project" in the single-chip microcomputer through the IO port control relay, relay access to GPRS circuit board power supply, so as to achieve the single-chip microcomputer on the GPRS circuit board switch control
• Circuit diagram

• Required components: a five-pin relay, 1 NPN transistors, 2 resistors, 1 diodes.
• component function, parameters and selection:

Five-foot relay: 1, 3 pin on, 2 and 5 connected, non-conduction when 2 and 4 are connected. The essence is a coil between 1/3 feet, which generates magnetism after powering on.

R4 the current limiting function, reducing the transistor Q1 power dissipation. resistance to take 1k~2k;

R10 The transistor reliable cutoff, that is, SIMPD14 or tri-state input, the transistor base charge can flow through R10 to the ground, to ensure that the Q1 cutoff. The resistance takes 5.1K.

The D2 acts as a reverse flow to prevent surges. Choose IN4148.

Q1 from the expansion of the role of the microcontroller IO Port drive capacity is weak, can be introduced or inhaled current small, through the Q1 common base circuit for current amplification, thereby driving the coil in the relay. Choose 8050.

12V Relay Switch Control