SparkFun Forums

[jandirks]

Hi,

I am looking for a special switch for an r/c airplane related project I am working on. I am a noob on electronics, so please bare with me, also English is my 2nd language, so I hope my description is clear to you.

I need a switch that has 3 positions (on/off/on) and it has to switch 2 pairs of 3 wires. See below.

1st position (on):
1st pair of 3 wires connected, 2nd pair of 3 wires not connected

2nd position:
1st pair of 3 wires not connected, 2nd pair of 3 wires not connected

3rd position:
1st pair of 3 wires not connected, 2nd pair of 3 wires connected

Requirements:
- handle upto 10-15A (preferably more, 20-30A)
- since this is aiplane related, it has to be light and small (a few grams)

Looking forward to see what is available!

Thanks, Jan-Dirk

[wiml]

You want a 3PDT (three-pole, double throw --- a "pole" is the moving contact, basically, and a "throw" is a switch position / stationary contact) switch, with a center-off position. That's what it'll be called in a catalogue. Searching for 3PDT on Mouser's website and looking for ON-OFF-ON switches (or "Center off", or "ON-NONE-ON", or some other indication that there's a middle position with nothing connected) turns up a handful of likely candidates.

The current requirement might be the hard part. Most run-of-the-mill switches aren't rated for more than a few amps. I assume you mean 10-15A DC? DC is harder to switch than AC, unfortunately. Most switches are spec'd for AC. They'll have a DC rating elsewhere in the data sheet, or a derating percentage, or something like that.

Also, some switches distinguish between their interrupting current rating and their non-interrupting current rating. If the switch is never going to have to be switched off when it's carrying a high current, then you can use a switch with a lower interrupting rating and a higher non-interrupting current rating. For example, if this is handling power to an electric motor driving the prop, then it's unlikely you'll be switching it on and off with the motor running at full throttle. I think. :-)

[jandirks]

Thank you very much. I found some switches at Mouser. They only accept credit cards and I don't have one, just can use paypal.

I bought a switch at the local electronics shop to do some test first, if everything works as it should, I will find someone with a card to order at Mouser!

Thanks again!

Jan-Dirk