Let's Make Robots!

Magnet to stop wires from twisting?

Hello, I am currently designing a robot that will have, well, a lot of circular motion when completed. Could I solder wires to thin and bendable magnets to transfer power, that can ride along an outer edge as the robot spins? If so, what type of magnets will I need?

Thanks!

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TeleFox's picture

A little dab of conductive graphite grease can help with keeping the contacts reliable inside the headphone jack. Just don't use too much or it will bridge between the contacts!

drewtoby's picture

Thanks everyone! Sounds like ill go for the headphone jack!

OddBot's picture

The cheapest and simplest slip ring is a headphone jack. A stereo jack is ideal for a servo.

The problem with slip rings is they can create a lot of electrical noise. For power this is not too much of a problem because you can use a capacitor to filter the noise. For digital and analog signals, a small cap can be used if the frequency of the signal is low enough.

So if your digital signal is a mechanical switch and your analog signal is a potentiometer then you can filter them without too much problem using a suitable capacitor. Start with 100nF but some experimentation will be required.

For high frequency digital signals such as an I2C connection then an optical link is better using some IR LED's and phototransistors.

For a high frequency analog signal such as audio, you can try a LED and LDR or you may need to convert to digital and used the IR LEDs and phototransistors.

mogul's picture

While it's really good advises you bring here I still find it funny to qualify audio signals as high frequency, but that might just be that I'm a bit old school here..

Indeed the headphone jack is quite nifty as a DC slip ring. Consider 6.3mm jacks for better electrical properties.

Duane Degn's picture

I hadn't ever thought to use a magnet like this. Interesting idea. If you get it to work let us know.

You'll want to be careful about soldering to a magnet since heat can reduce a magnets' strength.

I think the normal soluton for this is to use a slip ring. You can probably find less expensive version on ebay.