This is a school project to design and build a hand held battery checker with a bar graph display, to see if the battery is suitable (strong enough) to use in a smoke detector or not. it should indicate the battery voltage or health.
Please help as I have searched the internet and cant find anything this is my last resort and I only have a week to do this project! :(
2007-11-14 07:03:15 · 7 answers · asked by jonathan p 1 in Science & Mathematics ➔ Engineering
Most people just use their tongues. :P
2007-11-14 07:06:57 · answer #1 · answered by >>Phoenix<< 6 · 1⤊ 0⤋
I think it would take me a week just to get the parts. If you skip the bargraph part and use 3 or 4 LEDs, you could set up several comparator chips that are connected to a resistor chain that gives you the voltages for comparison and have each comparator light one light. You might use a green LED if the voltage is above 8.75 - fresh. A yellow one for above 7.5 (which I think is the lowest for good operation of devices, but check) a red one for just being on, but not above those volts. There actually may be a voltage bar code display out there in LED or LCD which you just match to a max volts, but can't point you to it.
2007-11-14 15:11:27 · answer #2 · answered by Mike1942f 7 · 0⤊ 1⤋
I've always just used a small light bulb and 2 pieces of wire (one + and one -)
You say you need a bar graph display? I don't know how to make one with that, but if you can convince your teacher to allow you to use light as the indicator of the battery's remaining power, you should be good.
2007-11-14 15:07:58 · answer #3 · answered by Deeder Magoo 3 · 0⤊ 0⤋
You need an IC called an Analog to Digital (ADC) converter. The input to the ADC is your 9 volt battery. The output of the ADC is a digital output which you connect to a bar graph display. The specs on the ADC and the bar graph display must be chosen properly. Good luck.
2007-11-14 15:14:46 · answer #4 · answered by Neil 7 · 0⤊ 1⤋
Radio Shack used to sell a battery checker.
The secret is to measure voltage under load.
So you need a light of some kind that draws power.
2007-11-14 15:07:38 · answer #5 · answered by Robert S 7 · 0⤊ 1⤋
clip bulb to battery in dark room & physically measure light emitted, then plot the results
2007-11-14 15:06:43 · answer #6 · answered by railwaysurfer 2 · 0⤊ 0⤋
http://www.allaboutcircuits.com/vol_6/chpt_3/13.html
http://faq.f650.com/FAQs/AftermarketVoltmeterFAQ.htm#Hand-held%20Voltmeter%20Usage
http://www.c-sharpcorner.com/UploadFile/mgold/VoltmeterUsingGDIplus11152005012714AM/VoltmeterUsingGDIplus.aspx
Not sure if any of these will help
2007-11-14 15:13:51 · answer #7 · answered by ? 6 · 0⤊ 1⤋