Push Button Start and Mag Toggle Switches

[Electrogunner]

Originally Posted by Sue

Merely my opinion, I would have the toggle switches
With guards over them in the down position. Engine
“On” guards up engine “off”. Right mag up, it’s off.
If backwards.... Flying along and and soda falls off,
you almost catch
It... oops as you reach for it you knock the switches
Down, oops throw them back up and boom, backfire!!
Hope you didn’t just blow your intake hoses off.
Same goes for a nice roll or slow loop, you fell through
And your iPad falls off and makes contact. Turbulence
Etc. only down side is canopy open and someone pushes
Down mags “hot”?

Locking toggle switches solves that. Then up can be on as usual.

[Paddy]

Locking toggles for Mags in this application. Push button bezel lights up and starter switch becomes active when key on and engine <600rpm. Once engine starts and exceeds 600rpm, bezel light goes out and switch becomes inactive, preventing accidental starter engagement while the engine is running. Engine restart required in flight and rpm <600; bezel lights up to prompt the pilot to engage the starter. The key switch is just there to stop kids and assorted curious types from hurting themselves while I'm not looking...

[wjb]

Originally Posted by scsmith

Question for Bill -- if I understand your schematic, you are 'grounding' your mags into the shield conductors of the leads. But I don't see where the shields are connected to real ground.

Also, is there a special reason for putting the momentary contact start switch between the two mag switches? Or could it be 'upstream' of both mag switches?

Hi Steve ... my understanding about grounding the mags is to short the points that would otherwise open and generate the spark. This will do that. The shield is grounded to the engine case through the mag body -- so there's your ground connection (good for RFI suppression from the HV in in the mags). All that really matters is that the points don't open electrically. I didn't totally dream this up, though, it's also a common pattern in the AeroElectric connection.

There's no special reason why the switch is in between the two mag switches .. it can go anywhere in line with that circuit. On my panel, it's a super easy connection, right next to the mag switches, so it caused no complications.

[RV7A Flyer]

Apologies for the watermark. Looking for a better hosting site for pics, but all the free options suck.

[RV7A Flyer]

Originally Posted by transientair

Thanks for the good info offered. Believe me, it's nice to know so many folks have such a wealth of knowledge.

I'm getting closer to having a handle on how to proceed, but I'm not ashamed to admit (mostly) that I still don't have it all together in my head.

I used a multi-meter to test the switch connections in the hopes of knowing with certainty how they operate. I used my crude skills to work up the below drawings. Remember I said kindergarten level, right?

There's a chance that I'll never quite understand fully the reasoning behind how everything is supposed to connect up, so the most helpful thing for me may be a very simple drawing that shows which wire connects to a specific switch connection. I have to admit that the wiring diagrams still leave me scratching my head!

https://1.bp.blogspot.com/-h1PgT8C5Q...g%2BSwitch.png

https://1.bp.blogspot.com/-0sdZnEnhU...t%2BSwitch.png

Thanks again

So the first thing is to use standard symbols...that way, you know what they mean, we know what they mean, Joe Schmoe EE knows what they mean, etc.

Second, get ahold of a good book (Nuckolls' Aerolectric Connection book is a good one) and learn the meaning of those symbols. Then get some of those switches, stick a multimeter on them and see for yourself how they work when flipped one way or t'other.

These are all really simple circuits, but they can be a little overwhelming at first sight.