Transistor for making an automatic switch for PIC

[itsahc]

Anybody know which transistor is very simple to use to make an automatic switch for PIC?I have use transistor 2N2222 and base(B) is connected to PIC and Emitter(E) is connected to ground and Collecter(C) to relay switch.I used 6V relay.Then i give 5V to the transistor using PIC portB and the relay switch can't function.

hope anybody cah help meThanks

 

[daviddlc]

Re: AUTOMATIC SWITCH

You need to calculate the right base resistor value.

You need to get the relay current, which is going to be equal to Ic.

From Ic you can get Ib from the next formula Ic = B Ib, you need to know the beta value (B), which you can get it from transistor specs or there are some multimeters to measure this

To calculate resistor Rb= Vr / Ib.

Vr = 5 volts (from PIC) - 0.7 (Vbe) = 4.3

With this values you can calculate Rb

Don't forget to add a diode to the relay coil to protect the circuit.

Added after 6 minutes:

Check this out

 

[daviddlc]

Re: AUTOMATIC SWITCH

What is the value for Vcc you are using ?

Added after 38 minutes:

Upps, the diode in the circuit should be rotated.

Sorry