WTK. Powering a relay

[thestroke]

I am currently trying to use an output signal from a microcontroller to activate the coils in a high power relay, but the microcontroller output is too weak to switch on the coils. What can i use to get the relay to switch on? Its a arduino microcontroller, and so far using transistors or smaller relays to switch on the larger are all I have in mind., but i dont want to do either. is there some kind of IC that i could use that utilises an external power supply to activate the coils?

 

[ronsimpson]

We need more information!
What is the coil rated for in the BIG relay. 24VAC, 120VAC, 12VDC 3 amps?
Send more data!

 

[ericgibbs]

I am currently trying to use an output signal from a microcontroller to activate the coils in a high power relay, but the microcontroller output is too weak to switch on the coils. What can i use to get the relay to switch on? Its a arduino microcontroller, and so far using transistors or smaller relays to switch on the larger are all I have in mind., but i dont want to do either. is there some kind of IC that i could use that utilises an external power supply to activate the coils?

hi,
Look at the ULN2308A ic.

As Ron says, wotcha doing.?

 

[SMUGangsta]

......and why are you looking for another chip, rather than a transistor of mosfet

I tend to use 2n7000 for relay driving, and the relay switches a load of over 75A DC

 

[Willbe]

I am currently trying to use an output signal from a microcontroller to activate the coils in a high power relay, but the microcontroller output is too weak to switch on the coils. What can i use to get the relay to switch on? Its a arduino microcontroller, and so far using transistors or smaller relays to switch on the larger are all I have in mind., but i dont want to do either. is there some kind of IC that i could use that utilises an external power supply to activate the coils?

Digikey relays with 5v coils will switch up to 1/2A at a current gain of ~500/10 = 50.
You might use cascaded relays and still do better than trying to squeeze current gain out of transistors. Certainly relays are hardier.