featherweight magnetic switch wiring

I have two featherweight magnetic switches one for a MARSA54L the other for a stratologger. The explanation for the wiring isn't exactly clear to me on the featherweight website.
but this is what I've done. + from battery to + in on switch. Neg. from battery to grd on switch. + from altimeter to "out" on switch. Neg from altimeter to grd.on switch. On both switches I get a blue light from the switch when I move the magnet across but no altimeter power.

It sounds like my setup. However, I usually take the negative from the altimeter directly to the negative on the battery, but that shouldn't make a difference. All I can say is double check to make sure your connections are where you think they are.

glenbo said:

I have two featherweight magnetic switches one for a MARSA54L the other for a stratologger. The explanation for the wiring isn't exactly clear to me on the featherweight website.
but this is what I've done. + from battery to + in on switch. Neg. from battery to grd on switch. + from altimeter to "out" on switch. Neg from altimeter to grd.on switch. On both switches I get a blue light from the switch when I move the magnet across but no altimeter power.

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Hi Glenn,

Neg from battery/neg power on altimeter to ground on switch. The other two terminals on the switch go to the pos and neg on the altimeter.

No I dont but I kind of thought that may be the problem. The config of the sled is a plug and play one that mounts on larger platforms for two different rockets. One rocket uses rotary switches which I have the doghouse harnes attached to the switch terminals of both altimeters. I may either create a bridge for that harness or try Michael's suggestion.

Wayco said:

Your wiring sounds correct, do you have a jumper in the "switch" position on your altimeters? Not sure about the MARSA, but the Stratologger has a position on the terminal block that must be jumped for power to reach the altimeter.

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On the SL100 you have to remove that jumper when using a switch.

Glenn, here is a pic of the front of the nosecone sled (altimeter side) for my Bull Pup. It clearly shows the SL100 and mag switch. This is the same method I used on all my sleds with the SL100 and the new StratoLoggerCF. I can't say for certainty that the MARSA should be the same, however if it has terminals for a switch, assuming there is no jumper on it or the board, then I would try this config if you haven't already.

You can see the green wire, which goes from the GRD terminal on the mag switch to the - terminal for power (same as battery). The other two terminals go to the terminals where the switch should be connected. In the pic they are the red wires. If the altimeter does not have + and - marked on it then you need to figure out which is which and connect the + term from the mag switch to the + switch terminal on the altimeter. As Wayco said, in the case of both the StratoLoggerCF and SL100, they come with a pre-installed jumper between the switch terminals, that has to be removed when using a switch. It is hard to follow the path in the pic but you can see the wires clearly on the mag switch and in the case of the green it is the only green wire I used.

View attachment 259064

Thanks Michael that illustration really helped.

Wayco said:

Although mpitfield has a beautiful setup there, it's more complicated than is necessary.

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Thanks for the compliment Wayco :wink: Obviously the old adage there are more ways to skin a cat applies here (no cats were harmed in the making of these altimeters). I can see other ways to wire it as well what we have both followed. When I initially worked out the wiring I reached out to Adrian at featherweight and here is a cut and past of his reply. My wiring was based on my interpretation of that.

"The Gnd terminal goes to the battery -, and the +In and Out terminal go to the PerfectFlite switch terminals. The +In should go to whichever Perfectflite terminal has + voltage when you connect a battery to it."

Im scratching my head so much I'm off to buy a wig haha. We're good.