I searched and all I could find was people needing help with water heaters, dryers, and generators. Is it 6 or 12 amps on modern motorcycles?
depends which system. lighting, charging, starting, ignition...? http://www.the12volt.com/ohm/ohmslaw.asp
That's what I was thinking. Depends on what part of system you're looking at. I have a friend that's working on building a water-brake dyno. He's asking questions now well beyond my basic electrical knowledge. "Here is my dillema this morning. We did dyno testing last night but we were unable to track engine speed (RPM) because the signal we wanted to use was a 12V signal. Basically what happens is the wire is constant 12 volt hot but then it will ground out when the coils spark causing 0 volts to show up. A counter program in the data acquisition counts the falling peaks and converts to RPM. Simple! Well but the data acquisition wants the typical 5 volt signal or it will blow up and level the building. So I think we'll jam a resistor in the line to keep a constant 12 amps but down to 5 volts so something like .4 ohms. Apparently it isn't that easy according to Mr. ----- so we need something called a "pull-up" resistor to bring it to 5 V. He keeps asking me for a schematic on the Hall effect sensor but it isn't a Hall effect sensor. I'm not sure what to do so we may just take an alternate right. Do you know anything about pull-up resistors?"
is he trying to modify the data system or the bike? not an electrical genius either but, it sounds like he needs a digital output current sensor as a pick-up for the ignition signal instead of tryin' to jack around with the bike's system, which is what i'm reading into this. is he asking for a schematic for the crank or cam trigger? it won't help cuz its signal is dealt with in the brainbox and NOone knows what goes on behind closed doors. well, bazzaz and them guys do.
Could you use a relay to trigger the 5V? The relay could be switched with the 12v and then run a 5v power generator thru the relay. I don't know if I'm explaining it correctly. It might be too much of a delay with the relay. Just a thought.
Um....your guy has amps and volts totally jacked up. I wouldn't expect this sort of slip up by an expert. Also there isn't such thing as a "pull-up resistor" as a resistor's function is simply remove the amount of amps hitting the other side. The wasted power is made into heat.
let's not confuse an online diagnosis any more than necessary... http://www.google.com/search?hl=en&q=pull-up+resistor&btnG=Google+Search&aq=f&oq= and...give .4 ohms to 12 amps at 12 volts and ya get 4.8v so, i'd say his expert has pretty good traction. a lot of times, you have to read between the lines.
#1 A pull up resistor is used to used to keep a logic signal on the high side. #2 Amps are constant with in a circuit, it is voltage that will "drop" across a load (resistor) #3 Ohms law will determine how many amps are flowing through the system. There are many ways to track a falling edge signal. Google can help. What type of bike are you testing with? Some bikes do use a hall effect sensor that will generate a square wave 5v signal. Cam position sensors on Yamaha's for example. Just remember to double the rate to relate to crank speed.
He finished the project and it works well. Very similar numbers to another dyno they tested on last year. Wish I did stuff like that in school. http://www.youtube.com/watch?v=s8eA-470Fy0
