But can your switch "kill"?

Minimichael

Minimichael

Well-Known Member
#1
#1
Working on a dashboard, of sorts.
PXL_20240304_061400818~2.jpg PXL_20240304_061201389.jpg

Repurposed heat shield, old indicator light, and two new led-lighted toggle switches...

This toggle switch offers to light up a number of different ways, such as green when on but red when off. Blue, but only when the headlight toggle is flipped on, etc... But it's my kill switch that I'm worried about, where "On" short circuits the spark plug wire and I'm also thinking will fry my whole electrical system.
PXL_20240304_031804067.jpg PXL_20240304_031727221~2.jpg

I want the led light to turn red when switched to off, as an indication the switch's contacts are open and the engine is ready to be started. And while I've got the instructions showing just how to wire for that color, I just don't see how I might safely use that switch for the dual role of lighting it's led from the battery, but also acting as a short circuit to the engine and be exposed to a lot of electrical feedback — even though the switch may be "off".
PXL_20240304_061449256.jpg

Hell, my regular plastic toggle switches with led indicator potential actually light up and flicker apparently from the engine's stray power leaking into the circuitry of the switch. I'm sure I'm not alone here.
PXL_20240304_060051600~2.jpg
And what about the moment I flip the toggle and close the circuit? Won't the engine's spark be short circuiting right into my electrical system? Or when the battery power is on, the switch is "on" to kill the engine, and I pull the recoil anyway?

I'm thinking now maybe the new switch could activate another somehow independent kill arrangement; or is there an electrical resistor or filtering module that could protect the system's circuitry but not defeat the switch's effectiveness as a circuit shorter?
 
Last edited:
sparkwizard

sparkwizard

#2
#2
You should not connect any of those to the spark plug wire, Sir.
If you use a lighted LED switch on the ground/kill wire of a magneto ignition, it won't light up.
You could use your battery power to control a relay. When you flip the switch, activating the relay, which shorts the coil.
You could use the relay to short the coil when activated (switch is on) or have the relay short the coil when deactivated ( switch off).
keep in mind, if the relay is activated , you are drawing power from BATTERY.

With a magneto ignition, ON completes the ground circuit and KILLS the engine. A relay can essentially reverse that, if you wire it correctly.
 
Last edited:
Minimichael

Minimichael

Well-Known Member
#6
#6
Yeah I'm worried about feedback, because I have always (5 whole years) wired my kill switches between the points and a ground connection. And I'm just saying the switch led flickers as long as the engine is running. Sparkwizard: maybe you mean the type of coil with a kill switch connector spade? I noticed you stressing "magneto", and that may be a nuance I'm not fully briefed on.

Anyway, all this seems beside the point now because I just don't see how the new switch can be led-lighted (and all set and ready to supply 12v to what its wired to — but also allow engine spark to feed through that switch circuit and flow to a ground connection. I think I'm needing the switch to be 2 switches in one: one that's wired for led power to sense when the toggle is on or off, but also one that operates as an isolated circuit, allowing the coil to ground out without the battery system feeling it.

The easier path here is to forget hooking this switch up to the 12v system. Instead, I could use the switch in isolation, and just for looks because I can't make it turn red on command but maybe I'll get a flicker!
 
Last edited:
Minimichael

Minimichael

Well-Known Member
#7
#7
Hold on, the relay idea got me thinking a small solenoid could mechanically actuate a micro limit switch (the real killer).

There's the piston solenoid and the magnet solenoid. So I'll noodle on that now...

Nevertheless, I'm still nagged by the role of the 12v system here because the bike also has to start regardless of whether the dc power is working. But if the battery is on, this multi-switch/solenoid arrangement controls.

This, because I want the switch to be red when it's okay to pull the cord! o_O
 
Mr. Pink

Mr. Pink

Well-Known Member
#9
#9
Minimichael said:
I think I'm needing the switch to be 2 switches in one: one that's wired for led power to sense when the toggle is on or off, but also one that operates as an isolated circuit, allowing the coil to ground out without the battery system feeling it.
Click to expand...
That is what is known as a DPST (double pole, single throw) switch.

1709636219144.png

1709636275548.png

Or if you are gonna get fancy with the LED side of your circuit, you go with a DPDT (double pole, double throw) switch.

1709636808571.png
 
Minimichael

Minimichael

Well-Known Member
#10
#10
Thanks, Mr. Pink. The visuals are much appreciated. Solenoid and a limit switch is where I think I'm going with this. Micro or not, it still feels overboard.. if they weren't so cheap. Thanks again
 
Last edited:
sparkwizard

sparkwizard

#11
#11
Minimichael said:
Thanks, Mr. Pink. The visuals are much appreciated. Solenoid and a limit switch is where I think I'm going with this. Micro or not, it still feels overboard.. if they weren't so cheap. Thanks again
Click to expand...
Sounds like you are trying to make your own relay. A relay is just an electromagnetic switch. (a solenoid activated switch)
 
Minimichael

Minimichael

Well-Known Member
#12
#12
sparkwizard said:
Sounds like you are trying to make your own relay. A relay is just an electromagnetic switch. (a solenoid activated switch)
Click to expand...
I guess so, but it's been difficult to wrap my brain around the final design. Suppose it's all the same because now that I've had a couple rides on it, I want more from that control.

In sum, it's now a dpdt connected to two separate circuits. When you flip it, it turns on an indicator light and turns off the engine kill switch. Well, I've already taken a liking to looking down and seeing that light - telling me that it's red and it's on and glowing and I'm riding and having fun. But now I want to know how long the fun will last, so now I want the indicator light or the switch or some other appliance to display the remaining battery charge. I can look at the battery scale under my leg, but not while I'm riding - so I'd like it on the dash with the tach and other stuff.

I might make a short video going over all that I've installed but still hope to achieve. That might clarify a little, and generate some still needed comments..
 
Minimichael

Minimichael

Well-Known Member
#16
#16
Yes. Just what the doctor ordered. And points me in a direction. Thanks.

And I wonder how the device can sense what the battery's beginning capacity is?
 
You must log in or register to reply here.
Top