i want to drive a 5V relay with pic microcontroller i.e when pin of controller is 5V i want to turn on relay.i am using vcc as 12V for the relay.but it isnt switching.i have used 1k resistor at base of bc 547 transistor.
attached is image of the cct
hi,
If the PORT pin is pulling up to +5V, with a 1K series resistor the Base current will be ~ [5-0.7]/1000 = 4.7mA
Assuming a Gain of say 15 for the transistor in saturation, thats a Imax of #65mA.
What is the current specification of the relay coil.?
Check that the transistor pins BCE are correctly connected and RD0 is set as an Output pin
Although the transistor can certainly be operating in the saturation region, you should pay attention to the fact that the current gain of the family of BC547 transistors is not defined by its numerical PartNumber, but the suffix -A, -B or -C.
yes it doesnt make any sense that is why i am not using transistor only anymore and using darling array and it works fine by giving 5v to 5v relay coil.
A voltage beyond the specified on relay coil should not necessarily burn it; Would perhaps continue for a time working overheated due to saturation of the magnetic core.
I do not have Proteus to simulate the operation of the circuit above, but I'll take a guess and suppose that the component model that you imported may have some mechanism that stimulates the error of polarization with a value above the one rated.