Using a magneto to power a small light - how to?

[Greg G.]

I set up a simple electrical circuit using a 6v battery, wires and alligator clips attached to a small light bulb (flashlight size) for Anita to show her pre-school class how electricity works.  I was thinking that as an alternative, the kids might get a kick out of using a magneto to do the same thing.  But how would it be hooked up?  I'm not even sure I have a spare magneto I can use, but first I would want to know how or if I could even do that.  It would have to be simple enough to just attach the clips in the right place, don't post schematics, I can't read them.

[compubit]

Electrical Engineer by training, but do IT now...

The key is knowing the output voltage (and current) of the magneto.  If I recall from what I've seen in the group, the output is in the 90VAC range (driving a ringer at the CO from your house), so you'd blow a 6v light bulb if you hooked it up...

Basically, you'd connect a wire from each terminal of the magneto to a terminal of the lamp.  Someone who has done this may have some better info (I focused on digital, not AC power systems...)

Jim

[Jack Ryan]

It would have to be simple enough to just attach the clips in the right place,

It is about that simple - you just need to identify where to clip the leads on the magneto. Post a picture of the magneto and someone will tell you.

You might try a 110 or 220 volt 15W pilot light. I just tried a 240V 15W pilot light and I can get an orange glow with a modest magneto.

It is also interesting to get the group to hold hands and the free hand at each end holds a magneto terminal.... But that's probably not allowed these days.

Jack

[Greg G.]

Electrical Engineer by training, but do IT now...

The key is knowing the output voltage (and current) of the magneto.  If I recall from what I've seen in the group, the output is in the 90VAC range (driving a ringer at the CO from your house), so you'd blow a 6v light bulb if you hooked it up...

Basically, you'd connect a wire from each terminal of the magneto to a terminal of the lamp.  Someone who has done this may have some better info (I focused on digital, not AC power systems...)

Jim

So it's too much for a flashlight bulb, but am I correct in understanding that it would not power a standard light socket?  I have a porcelain socket NIB kicking around that says 660w/250v.  What light socket/bulb combination would I look for that would work safely with a magneto?  I don't want anything that would blow up in the kiddies faces!

[Greg G.]

It is also interesting to get the group to hold hands and the free hand at each end holds a magneto terminal.... But that's probably not allowed these days.

Jack

Kinda reminds me of this video clip: https://www.youtube.com/watch?v=NaEfU47QY_k

[Greg G.]

It is about that simple - you just need to identify where to clip the leads on the magneto. Post a picture of the magneto and someone will tell you.

You might try a 110 or 220 volt 15W pilot light. I just tried a 240V 15W pilot light and I can get an orange glow with a modest magneto.

Jack

I think the only magneto I have available is from my busted Beehive phone.

[Jack Ryan]

I think the only magneto I have available is from my busted Beehive phone.

That will do - I think it is bigger than the one I used.

Jack

[G-Man]

15 Watt lamp is doable but still pushing it for the average hand-cranked telephone magneto.

Since you don't want to have to physically crank too hard in order to make it easy for the kids, a standard 7-1/2 Watt (night-light) to 10-Watt bulb would be ideal.

The lamps should be standard 110-120 Volts or so since the mags typically output anywhere from 65 to 110-volts. Since there are only two wires to hookup, connections would be extremely easy to make.

[compubit]

So it's too much for a flashlight bulb, but am I correct in understanding that it would not power a standard light socket?  I have a porcelain socket NIB kicking around that says 660w/250v.  What light socket/bulb combination would I look for that would work safely with a magneto?  I don't want anything that would blow up in the kiddies faces!

The socket just has the rating for the max bulb you can put in.  A 5-10 watt 120V bulb  would probably be the best - not sure about an LED bulb (depends on the junction voltage of the LED bulbs) - but that might be easier to light.

Jim

[DavePEI]

I agree totally with G-Man - a 7 1/2 watt bulb is perfect. If you use a 15 watt bulb, it will make cranking very difficult. From experience, I know a 7.5 watt bulb works well. A good choice would be an old exterior 120 volt (the large ones) parallel christmas light.

Of course if you want to be really mean, you could charge up a large electrolytic capacitor and toss it at them to see how many drop it very swiftly, as one shop teacher in my past liked to do to kids. (No, he never suckered me in on that one - I knew better than to try to catch it!)

Dave

[Greg G.]

Good info guys, thanks!  I have nightlights or Christmas lights I can use.  I'm wondering about the magneto though.  I unpacked the Beehive phone to check it out.  I'm wondering if the little squirts would be able to crank it (we're talking about pre-K, 4-5 yo), it seems kinda stiff.  At the least, it would need a good lube job to make it turn easier, even then Anita may have to help them.  At worst, this is the one the auction house did a bad packing job on.  Consequently it arrived damaged and I'm not sure if the magneto even works.  I may have time to find an unattached working magneto on ebay or somewhere.

Beehive magneto demo:  http://youtu.be/F6eSlSWfJ0g