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Amplifying ATmega8 signals

I am doing my final project for school at the moment.

I have a bit of a problem.

I use my ATmega8 with a BD243C transistor to switch a relay.

Now is the problem that the signal that goes to the transistor is to small to fully switch the relay. I was wondering if I could use this(http://www.datasheetcatalog.com/datasheets_pdf/T/L/0/7/TL074CN.shtml) TL074CN IC for amplifying the ATmega8 signal and so fully switch the relay. Can this be done?


I have not much time left to finish this project, so I would appreciat all help.


Danny Temmerman

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The relay operates at 5v? or do you have external power just for the relay(s)?

No, its a 12V  relay.

My ATmega8 is run at 5V with a voltage regulator and the relays are switched at 12V throught the transistors. The relays switches motors of around 10A.


you can use one more transistor, mounted as amplifier between your micro and your original transistor


something like


but I think one transistor should work.

there are some nice simulators out there that you can use to help you do all the calculations


Tnx for the advice, but I already bought that chip in a hurry.

You think the chip will work? Hope it does.

But I gues it was better to buy a few small transistors.

But hey, I will first try with chip this thuesday. And if that doesn't work I will go with the transistors.



Tnx again, Danny Temmerman