Need help with some circuitry

[pushVTEC]

My friend is looking for something that will take a wire with input voltage from 0-15+ volts, he wants to make an LED flash when battery voltage goes under 11.5V, and flash double fast
when over 15V. Anyone know of something that may be able to do this?

 

[Zugzwang152]

no but i'll bump you up anyway.

 

[Yo Ma Ma]

I don't know of a specific part, but you could check some places such as http://www.digikey.com/ and see what you can find.

 

[maximus maximus]

Originally posted by: pushVTEC
My friend is looking for something that will take a wire with input voltage from 0-15+ volts, he wants to make an LED flash when battery voltage goes under 11.5V, and flash double fast
when over 15V. Anyone know of something that may be able to do this?

Yup. I have an idea. May work... may not work.

Firstly, you need 2 reference voltages. One which can give you a fixed voltage of 11.5 volts and another which can give you a fixed voltage of 15 volts.

(I would suggest you use Voltage regulator IC's for that. They are pretty dependable).

You can then compare your input voltage with these 2 IC's and then implement the logic of flashing LED's.

Max.

 

[maximus maximus]

Lemme know if it works.

 

[Demon-Xanth]

There are actually LEDs that basically do atleast half of what you want to do.

 

[nwfsnake]

Never mind, for your app it wouldn't work!

 

[pushVTEC]

Yeah this is going to be used in a car application. Pretty much the voltage is running off the o2 sensor, depending on the voltage is how rich/lean the car is running so he wants to make a light blink if he's running dangerously lean. The only constant source in the car that could act as a reference is the 12v accessory wire.

Maximus: i'll look into those regulators

Demon: where could I find LEDs like this?

He's a mechanical engineer and I'm a CSA major so we kinda know what we need just don't know what stuff actually exists and what we need to fab up. Are there any good sites other than the one mentioned to find this kind of equipment?

 

[pushVTEC]

bump

 

[walla]

well you could use a PIC microcontroller with ADC, but that'd probably be overkill

 

[Eli]

lol... n00bs.


http://www.reconnsworld.com/power_highlowbattmon.html

http://homepages.which.net/~paul.hills/...its/BatteryMonitor/BatteryMonitor.html

http://www.zenreich.com/ZenWeb/motorcycle/batterymonitor.htm

http://homepages.which.net/~paul.hills/...its/BatteryMonitor/BatteryMonitor.html

http://circuitos.tripod.cl/schem/r82.gif

http://www.edn.com/archives/1997/010297/01di_04.htm

http://members.ozemail.com.au/~bobpar/ledvolt.htm

http://www.elektor-electronics.co.uk/De...art=51833&group=Test%20&%20Measurement

http://www.cyclegadgets.com/Products/product.asp?Item=BOVOLT

http://www.signaldynamics.com/products/Modules/HUVM.asp