Neon sign transformer fried Hall throttle ? FULL ON

So yesterday after getting back form a rip on a few of my bikes, me and a friend were messing around with his high speed camera and making arcs using a high voltage Neon sign transformer, some silicone wire with ends stranded apart for extra effect....

All of a sudden, my KMX trike ( 100v X5 on lipo ) that was powered up but had been sitting there for a while, about 4ft away, suddenly came to life.. ripped thru the garage, pinned itself against my fatbike and burned rubber while i ran like a madman to shut it down.... ( back wheel burned a nice skid mark into my plastic covered floor lol )

I propped the wheel off the ground and tested it again, sure as shit.. she's going until i disconnect the throttle.... so i replaced it and the trike runs again properly... but how is this possible ?

anyone ?

E
M
P


Hall sensors and EMP don't get along. It's a magnetic sensor, it senses magnetic pulses at 5 volts. High voltage discharge makes some wonderful electromagnetic pulses at high voltage. The results can be ... shocking.



So, did you get this on slow motion?

Ha... we said the same thing.. but sadly no, it was not caught on camera... mabe we can stage a recreation lol

I can see how the EMP might make the throttle act up, but permanently fry it from 3~4ft away ? in a full on state ?.... i've had hall throttles fail and no longer work, but never one that would fire off full on ?

It's not EMP, per se--it's the bursts of RF transmitted from what amount to miniature lightning bolts.

That RF gets picked up by wiring, which is all antennas to it, and under the right circumstances, depending on the electronics attached to either end of the wire, can be rectified into a DC voltage sufficient to trigger behavior on whatever is there. In this case, the throttle input to the controller.

Or it could just stay in an AC form, at multiple frequencies, where the RF (an AC voltage) induced a current (possibly even a reverse current) into the wire which flowed thru the hall sensor (and/or controller input) possibly backwards as well as forwards (alternately), (which gives a better chance of frying something).

This can happen with any sufficiently powerful radio source, even a single-frequency AM-radio carrier wave, but electric arcs are worse about it because their transmissions are broadband, across a whole range of frequencies, and though that means the total power on any one frequency is lower, the chances that some energy will get thru are higher, and cause havoc in there.

I ran pack voltage through a hwbs ebrake hall sensor accidentally and it also remained on.

That's pretty wild an arc that wasn't even visibly close enough seems to have grabbed up into the throttle circuitry and fried your throttle hall sensor. (btw that's some real excitement to have have a runaway, esp inside )

Do you think the arcs were drawn in more by the electrified electronics? (wives' tale says to turn off the fan in the window when it is lightning . . .)

Will a stun gun harm things similarly?

As I noted above, it's not the arcs themselves, its the RF, and the wiring that acts as antennas. (radio frequency = RF)

You can look up how this works on the web.

I vote to delete all info regarding this development.. . . .
Could you imagine the hayday the police would have if they found out about this little discovery? They've already collaborated with the military about getting their hands on those car stopping handheld RF guns. Think what will happen when e-bikes become more common?

Guess its time to a EMP-proof the our e-bikes. I had planned on making a windscreen/enclosure eventually for all weather riding. Suppose it will not be that much more effort to integrate a Farraday cage into it.

If you wanted to faraday-cage things, just use metal braid over all the wiring, and ensure it's all connected together to enclose the system.

For small wires you can strip the braid off old RF cables from TV stuff.

For bigger bundles, you can strip the braid off stainless-braid-covered water hoses, like those used on toilets or washing machines, for example.

you can also buy the stuff new, but I like recycling old stuff that isn't usable for it's original purpose anymore.

I wouldn't worry about it RageNR, it's well known already what EMP does- Dod and the like aren't learning much here imo.
Or yes, or you could try to shield the circuits.
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I'm not sure what there is to argue about on definitions, probably because I don't know much AW.

RF is electricity too, as well as emp. So the electricity from the transformer arcing fun made it's way into the circuitry and fried the hall with too much voltage.

Perhaps it's rudimentary but I assume it could still be called an 'arc' of 'electricity' (or EMP) even if more technically preferably referred to as 'RF pulse'.

Different frequencies perhaps, though I can't find that applicative when the important part is the source (transformer) and how it got into the circuit (arcing). Feel free to explain more technically though!

I expect the same could happen to motor halls since they're just as sensitive.
I speculate having the circuit energized may have upped the chances of the damage that occured.

There is some difference in the way each of these things works, which is why I made the distinction.

THe arc itself is a current flowing thru the air (as plasma) rather than a solid wire conductor.

RF is simply broadcast waves, not a current like the arc. It can induce a current in a conductor that it passes thru (antenna), which is what almost certainly happened in this case.

But the arc causes RF broadband broadcasting, and the higher current/voltage the arc is, the more power there is in the RF, so the more induced current there can be, depending on the frequency and the antenna's length (the shorter the antenna, the higher frequency it will need to be to be picked up; a longer antenna can pick up longer wavelengths (lower frequencies), as well as shorter wavelenths, so the longer the wires are, the more likely they are to pick up more total power, in general).



It also doesnt' really make any difference whether the circuit is powered on or not, as to whether it picks up the signals. But sometimes having power present may cause diode operation to already exist in some semiconductors, allowing current induced from RF to flow sooner (as it doesnt' have to turn on the diode or other circuit path first; it's already on). Most circuits are probably going to be affected regardless, if the RF is of sufficient power.

Some electronics are designed to protect against such things, and some expect the engineer to provide that protection externally, or use them in an environment that wouldnt' have these things.

See the warnings on various devices that say stuff like "this device must accept any interference even that causing undesired operation", which are warnings that some devices themselves broadcast or use RF but could unintentionally receive RF that makes them do stuff they shouldn't; in order to protect against this it might break FCC/etc rules for one reason or another.

I wasn't being serious FWIW. If the Popo wants to put their finger on the man, they will find a way.

I imagine the hall sensors in the motor were shielded by the case more than the exposed one.

As for actually shielding the the wires from RF or EMP, that would be a difficult task. So many places could be left exposed.
And I have plenty of scrap lying around. Ever seen what a commercial dishwashing station sprayer looks like? They are SUPER beefy. Lots of good to use there. And they all fail because of the hose inside the stainless shielding breaks down and blows out near the sprayer wand. The cost to repair is more than a new unit. Suffice to say, I have a few of those lying around.

RageNR said:

I imagine the hall sensors in the motor were shielded by the case more than the exposed one.

Click to expand...

Unfortunatley it doesnt' matter if the sensors are shielded or not, as long as there are any wires hooked up to them that are not shielded, too. They'll act as antennas that pick up the RF and carry it along to whatever they're hooked up to.

As for actually shielding the the wires from RF or EMP, that would be a difficult task. So many places could be left exposed.

Click to expand...

Yep--but the less length that is exposed, the less RF power that gets thru, so the less likely that you'd get destructive levels of current flowing.

Thanks for sharing your knowledge AW, that's some pretty awesome stuff!

Just bits and pieces from my ham radio daze.

(and bits of research and experiments from around then when a friend was building one of these neon-sign-based tesla coils, and a jacob's ladder).


One other thing--more modern technology uses smaller and smaller silicon chips, so overcurrents from external sources can be more likely to destroy things in them, vs older larger-chip tech, or discrete component tech. But...more modern technology also can include design experience with mitigating these things, meaning if things are done right the newer stuff may be more likely to survive...up to a point where protection is overwhelmed.

very interesting !!!.... experiments in my future

Ypedal said:

So yesterday after getting back form a rip on a few of my bikes, me and a friend were messing around with his high speed camera and making arcs using a high voltage Neon sign transformer, some silicone wire with ends stranded apart for extra effect....

All of a sudden, my KMX trike ( 100v X5 on lipo ) that was powered up but had been sitting there for a while, about 4ft away, suddenly came to life.. ripped thru the garage, pinned itself against my fatbike and burned rubber while i ran like a madman to shut it down.... ( back wheel burned a nice skid mark into my plastic covered floor lol )

I propped the wheel off the ground and tested it again, sure as shit.. she's going until i disconnect the throttle.... so i replaced it and the trike runs again properly... but how is this possible ?

anyone ?

Click to expand...

So your controller doesn't have some kind of throttle high-on-start ow whatever protection?

Ypedal said:

very interesting !!!.... experiments in my future

Click to expand...

Are you sure you don't have a ghost in the house??? Just kidding

As AW explained you were broadcasting current through the air. 5v+ at the distance. Tesla did it a long time ago....The birds and bees and fish be dammed.....Not to mention the worms.

So if you want to experiment, get a 6v light bulb, place it 4ft or so from your arc, don't wire it to anything...start the arc and turn out the lights in your place to see if the 6v light bulb illuminates. Move it around to see what you get. If it does, proof of concept. Try incandescent, florescent and led to see what they can do. If nothing happens attach a diode to one polls on the bulb and try to isolate the ac that your arc is probably emitting.

Sounds fun!