DIY reserve light

[Ichy]

I'm building a bike and after suffering with previous efforts I've fitted a CBR fuel level sender in the tank.

Unfortunately I have no idea on how to covert the signal from it into a lit LED.

Can any one send me a circuit diagram of how I get a LED to light from a switch once it reaches zero resistance without putting any voltage through it?

[Alexio]

Wouldn't you use one of those electromagnetic switches?

https://en.wikipedia.org/wiki/Reed_switch

The voltage could power an electromagnet which closes a circuit - that circuit could either short circuit the LED or you could use a small NOT logic gate I suppose?

Either way, when voltage is low enough you'd not be able to power the magnet. I'm in no way an electrician and know pretty much nothing about electrics but this was the first thing that came to my mind and how I might attempt this problem. I'm sure there's an easier way to do it though?
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will never give up his CG. I look at my fuel gauge more as a progress bar than a fuel gauge.
G: With my GSXR I do often effectively use it as a scooter with a clutch in town.
ms51ves3: why does it need 500 miles? Are you teaching it how to be a piston?

[Fortuna]

They are basically a switch themselves that usually when closed (short) allow a very small voltage to travel to the ECU. Depends on model.
They also need damping in the electronics otherwise they would flick on and off mentally. This is usually done in the ECU, it waits for say a continuous short state of 2 minutes before it will light the fuel low on the clock.

[Tango675]

Is the sender for a fuel gauge or a fuel light?

If its a simple switch (fuel light) and should be very simple to wire up (on, off).

If its for a fuel gauge, i would swap the sender for a fuel light one as it will make things a lot simpler and less prone to error (battery voltage drop etc.)

Or just put a gauge from a CB on the other end.
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Somebody give that windup merchant a torque wrench..

[Ichy]

On the CBR the sender doesn't feed through an ECU and it just turns a light on when the fuel is low. The sender just makes a circuit.

I'm guessing I either need to somehow measure resistance and turn on the light when its 0k or I just need to check for when the circuit is made. I just don't have the electronic knowledge to work out how to do it.

[The Shaggy D.A.]

I'm guessing the sender is a variable resistance type, rather than a switch. You could alter this circuit, replacing the phototransistor with the sender, and the 1K resistor with a variable one, so you can set the sensitivity. You'll probably want a dropping resistor inline with the LED, seeing as it'll be 12v, not 3v

https://www.evilmadscientist.com/article.php/nightlight

Problem would be smoothing the output, otherwise every bump you went over would leave it flashing.
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Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[Ichy]

[carvell]

[Ichy]