The easiest way to measure a motors resistance, is to lock the shaft, and apply a known exact voltage to it, and measure the current draw at that voltage.
Then just calculate the resistance. Easier, is if you have a power supply that can be limited to exactly 1 amp. I use a cable setup with two leads coming off two of those big copper alligator clips. One set of leads goes to a volt meter, and the other to a regulated power supply. I reverse the method a bit by shorting the two clips together, and adjusting the power supply for exactly 1 amp. You look at the voltmeter (millivolts), and 1 millivolt = 1 milliohm. Do this first to get the resistance of the clips (the cables are not part of the circuit, since the voltate measurement is at the clip) Now, attach the clips to the motor terminals, and read the resistance on the meter (again, you read millivolts, but at one amp, 1mV = 1mOhm) and subtract the clip resistance, and you have your motor At 10:39 AM 2/8/02 -0600, Tim McCann wrote: >Question for the F3Bers. What instrument (s) do you use to make this >measurement? Looks like it >would have to be a 3 channel, triggered programmable digital storage volt >/ ammeter. >---------------------- From: ANNEX 5C, CLASS F3B----------- >The measuring equipment measures simultaneously the voltage of the battery >(Ub), the voltage drop at >the motor Um and >the current I, no less than 150 milliseconds and no more than 200 >milliseconds after the voltage is >applied and during >which time the motor shall have stopped rotating. >RCSE-List facilities provided by Model Airplane News. Send "subscribe" >and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
