Fuel warning light delay

The original circuit in the link does not work for your gauge/sender, or anyone else's for that matter, and the two minute timer idea also stinks. The low fuel indicator on a modern vehicle is a warning light, and being such would do you no good if it came on just when the tank is empty. You need to decide on a warning mileage, say Mw, which is the minimum distance you want to allow yourself to refuel when the indicator lights. Then if MPG is your worst case miles-per-gallon and C is the tank capacity, you want the low-fuel warning ON at (Mw/MPG)/C fraction of full scale reading of the gauge, or 1/16th full scale, whichever is greater. When the gauge/sender junction voltage falls below this threshold, the lamp driver should latch on. This mean it comes on and stays on regardless of subsequent changes in the sender state. The low-fuel lamp is extinguished when the ignition circuit is turned off. Most of the time, any accelerations that trip the circuit mean the fuel level is low enough to alert the driver anyway. It should be rare that it comes on with more than 2x the low-fuel level setting.

The low fuel indicator on a modern vehicle is usually simply a self-heating thermistor immersed in the fuel at about the 2-3 gallon level. When it gets out of the cooling fluid its resistance drops rapidly operating a relay.

I had a 280ZX that talked to me, "Fuel is low, the passenger door is open," etc ;-)

...Jim Thompson

I can make my Nissan lamp latch on at 1/4 tank when the static level is more like 1/16th tank.

In article , Jim Thompson wrote: [...]

I knew someone that had a Dodge something that did that and reminded you to use your seat belts. It was seriously broken so that every time you turned it on, you had to listen to this very long list of things that are wrong.

It was not broken- it was designed for the typical Dodge owner....

Sno-o-o-o-ort ;-)

...Jim Thompson

Actually, I'd like to finish the restoration on my '79 Dodge pickup truck. It was one of 1000 made in a special edition. It came from the factory with a fiberglass cap, and was painted yellow with a deep brown wood grain trim. I have a rebuilt engine with a little over 1000 miles on it, but I still don't have the strength to exchange it with the original engine. BTW, it has the solid state voltage regulator and solid state ignition, but no computers.

I saw my VA doctor last week. She changed my Diabetes medicine again, for the third time in six months. It just doesn't want to come all the way back down. It was normal for over a year, then my blood sugar shot up to 497 in a two week period. Its still too close to 200. :(

In article , Michael A. Terrell wrote: [....]

OUCH ... ouch

For those who don't know, any number over 150 is considered to be a threat to your long term health.

Someone I work with has a son with type-1. We really need a way to measure blood sugar without punching a hole to get the blood. This could either pass light through your body and detect some effect or something that gets implanted once and activated through the skin anytime a measure is needed.

We then could start arguing over LM555s an blood sugar warning lights.

Indeed. Ouch! My wife has more problems keeping hers up than down. Crashes to 90 and below aren't fun either.

AIUI, there are some that take subQ fluid from the arm. My wife's doctor doesn't like them so won't prescribe one. Searching the net I see some talk about scanning the conjunctiva so maybe...

You'd use a 555 to drive an LED? ;-)

An implanted sensor isn't conceptually that difficult - there's all kinds of implanted stuff out there these days, and they've had those RFID chips for pets for years; I saw some "CSI"-type show where idle rich kids got them implanted in themselves, and had it read out their credit card number, so they didn't have to carry any ID or cash or anything, to go to the rich kids' disco or whatever. But that was teevee - I don't know if they're ready to actually implant them in people yet. but, a sensor, a micro, and a little reader about the size of a key fob... hmmmmm......

Cheers! Rich

Not a whole hell of a lot - it took some digging, but I finally found:

Where it says Voh == Vdd - 0.7 @ -3 mA. And they can't sink much either, Vol == 0.6 @ 8.5 mA.

Cheers! Rich

I treat diabetic animals, currently measuring blood glucose from samples, I also implant a great many RFID chips, it would be good indeed to be able to combine the two functions in the implantable device. getting blood from animals can be more hassle than from (most) humans. I know ion-selective electrodes are pretty specific for certain anions/cations, but anyone here know about selectivity for organic molecules such as glucose? I wonder if this sort of in vivo chemistry analysis is happening yet? I believe the military are very interested in implantable biomedical telemetry, wonder where they have got with this sort of technology.

Steve

Look at the Glucowatch. Uses a membrane 'patch' under a wrist watch, and electro-osmosis. The 'downside', is that it is nearly 90 minutes after the patch is applied, that the system starts working properly, but otherwise, provides a non-intrusive way of testing the blood glucose level automatically every

Best Wishes

In article , Steve wrote: [....]

How about an absortion line for glucose and an LED at that frequency?

In article , Keith wrote: [....]

Not really. Its more likely that I'd use a TN2510 from Supertex. The logic that decides to turn it on is likely going to be in a CPLD.

In article , Rich Grise wrote: [....]

That is enough to bias on a transistor that runs an LED but not really enough to run an LED directly. This seems like a mistake by microchip. I'd have expected at least a strong pull down.

One nice thing is that the PIC does run on 5V so you have enough swing for a MOSFET.

I'm not aware that you can measure glucose directly by spectrophotometry - the in-vitro assay I've done using this method relies on the production of a reddish coloured dye after reaction with reagents (glucose oxidase/PAP). Glucose is also measured using small meters nowadays, which do some chemistry on an enzyme coated strip and measure the electrochemical effects of the reaction, again not a viable continuous in-vivo monitoring method.

Steve

Energy is what human life is founded upon. Nobody can move without energy.

Most of the World's troubles arise from the USA trying to gain control over the World's energy resources. Oil, natural gas, etc., are the immediate objectives. They have been quite successful.

But FOOD is itself the greatest energy resource. There's not enough of it to go round. The Earth's population is already too large.

And so we have the USA selfishly interfering in the World's politics and economic organisations which ultimately affects the world's farmers - the ultimate energy producers and generators.

Not that USA citizens are more selfish than the rest of the World. But being human, they can't help taking advantage of the fact that they have far more hydrogen bombs than the rest of the World put together.

They also have George Bush. And the British still have Tony Blair.

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Except that we provide a substantial amount of the food going to third world countries.

And we have to put up with Reg Edwards ;-)

...Jim Thompson