Electromagnet

[Mike]

I'm working on the Robovation bot, and I thought it would be pretty cool if I could have a crane type thing with an electromagnet at the end. Then I could pick up nails and stuff. How would I be able to supply/take away power from it? I know it'd be something to do with the Digital In/Out ports.

Thanks,
-Mike

[Al Skierkiewicz]

Mike,
In checking the IFI site, the controller is designed to feed "mini solenoids" on the six solenoid outputs. Each output is TTL level and can sink 85 ma. If you were to find a miniature relay designed for 5 volts and less than 85ma coil current you could use it to control the current to a magnet structure. The source for the magnet would need to be external to the controller (so as not to draw excessive currents.) and the relay contacts need to be able to handle whatever current the electro magnet requires.

[Sparks333]

You would need to use a power source that can supply plenty of current, so I would use a relay controlled by robovation controller (the EDU robot controller?) rather than simply take the current from the controller. As an electromagnet's strength comes from the amount of current you can pass though it, I would not recommend using the controller as the electromagnet's source of power.

Sparks

PS: Be sure you don't short out the battery. Typical copper wire has a very low resistance. Don't let current run rampant through your system.

[eugenebrooks]

Mouser part number 653-G6E-134P-DC5 should do it,
the coil is designed for 5 volts, and the relay drive
current is 40 ma. We selected this one to drive
transistors for a programmable battery load tester.

The spdt relay handles 3 amps.
If you need to control a bigger current,
use this relay to actuate a bigger one.

Originally Posted by Al Skierkiewicz

Mike,
In checking the IFI site, the controller is designed to feed "mini solenoids" on the six solenoid outputs. Each output is TTL level and can sink 85 ma. If you were to find a miniature relay designed for 5 volts and less than 85ma coil current you could use it to control the current to a magnet structure. The source for the magnet would need to be external to the controller (so as not to draw excessive currents.) and the relay contacts need to be able to handle whatever current the electro magnet requires.

[Sparks333]

Originally Posted by Al Skierkiewicz

Mike,
In checking the IFI site, the controller is designed to feed "mini solenoids" on the six solenoid outputs. Each output is TTL level and can sink 85 ma. If you were to find a miniature relay designed for 5 volts and less than 85ma coil current you could use it to control the current to a magnet structure. The source for the magnet would need to be external to the controller (so as not to draw excessive currents.) and the relay contacts need to be able to handle whatever current the electro magnet requires.

I was checking that too. If a you could make a switch that was controlled by PWM, the PWM ports are designed to take up to 4 amps. By that time, though, it would be easier to just to go with a relay.
Just food for thought.

Sparks