Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: krazykajun05 on April 06, 2008, 09:54:13 AM

Title: Relay for a Motor
Post by: krazykajun05 on April 06, 2008, 09:54:13 AM

I need a relay that will switch a small motor from forward, reverse, and off.  Any suggestions of where to find one? Thanks

Title: Re: Relay for a Motor
Post by: airman00 on April 06, 2008, 10:16:03 AM

what are the motor specs?


check out allelectronics.com


also, why are you using a relay and not an H bridge or motor driver

Title: Re: Relay for a Motor
Post by: benji on April 06, 2008, 10:32:07 AM

you dont need a relay unless you are dealing with a relative high voltage operating motor(above 25 volts).
and if you need one there are 2 types of relays, dc and ac
the dc operates at 24 volts and it can pass a relatively big current through it
the ac ones need ac voltage at its input to conduct

just google dc or ac relays and youll get big info about em

Title: Re: Relay for a Motor
Post by: airman00 on April 06, 2008, 10:33:28 AM

Quote from: benji on April 06, 2008, 10:32:07 AM

the dc operates at 24 volts and it can pass a relatively big current through it

there are many types of relays , many even rated @ 5V

Title: Re: Relay for a Motor
Post by: benji on April 06, 2008, 10:37:02 AM

Quote

there are many types of relays , many even rated @ 5V

thats a better one i guess if you dont need very big currents at the output

Title: Re: Relay for a Motor
Post by: airman00 on April 06, 2008, 10:39:10 AM

Quote from: benji on April 06, 2008, 10:37:02 AM

Quote

there are many types of relays , many even rated @ 5V

thats a better one i guess if you dont need very big currents at the output

yep

but relays have a limited amount of switching times , whereas H bridges last almost forever

Title: Re: Relay for a Motor
Post by: benji on April 06, 2008, 10:47:42 AM

relays have slower switching than transistors (bridges) too

Title: Re: Relay for a Motor
Post by: krazykajun05 on April 06, 2008, 03:13:36 PM

Thanks for the info.  I am trying to control two motors, one for each set of tracks.  Therefore I can steer the robot by switching one track forward and the other reverse, like a small tank.  The motors are can be powered by 1.5-3V, 0.2 Amps.  Sounds like the H-brigde is the way to go.

Title: Re: Relay for a Motor
Post by: airman00 on April 06, 2008, 04:00:31 PM

Quote from: krazykajun05 on April 06, 2008, 03:13:36 PM

Thanks for the info.  I am trying to control two motors, one for each set of tracks.  Therefore I can steer the robot by switching one track forward and the other reverse, like a small tank.  The motors are can be powered by 1.5-3V, 0.2 Amps.  Sounds like the H-brigde is the way to go.

I would suggest using the L293  chip

search google for details

we can help you out with it

Title: Re: Relay for a Motor
Post by: Admin on April 14, 2008, 07:13:41 PM

fyi, you can make H-bridges using relays. The old motor drivers back in the 90's used relays - I still own some too.

But obviously its much better using mosfets for an H-bridge . . .