Motor measurements related to use design
LoopyByteloose
Posts: 12,537
I was thinking of building a Solor Roller which requires a low voltage motor.· So I picked up a Universal Motor form Tamiya that operates at 3 volts.· I figured I could measure the current in actual free running operation and measure the resistance from the two connections to get a good idea of what size of Mosfet [noparse][[/noparse].3 watt, 1.0 watt, etc.] to use.
It may not be the right motor because it has gears and these may interfer with free rolling when there is no solar power.· Being geared down may actually act as a brake.
Anyway, I was surprised to fine in drawing 13 amps or more at start up and between 8 and 6 amps in steady operation.· This seems way to much.· Also, the resistance measurement registered infinite.· I guess some brush motors just won't provide the information.
So, what I am wondering is how does one locate and select a good motor?· I have about 10 out of CD drives that I can directly drive a wheel in a tricycle with the single wheell providing the power or I can continue to fool around with the Tamiya gear box and swap out other 'standard hobby motors'.· I could even disassemble a hobby motor and rewind it to enhance performance.
What I do know is that my solar cells cannot provide steady state 10 amps and maybe only 1 amp tops.· So I am looking at some kind of Solar Engine that charges a bank of·super capacitors and then gives a pulse of energy.
After that is all done, I am considering having an SX20 operated from a 3 volt button battery become the Solar Engine in a programible format.
But first I need to get the motor right.· Eventually, I was thinking of having a Solar Line Follower as a contest format.
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It may not be the right motor because it has gears and these may interfer with free rolling when there is no solar power.· Being geared down may actually act as a brake.
Anyway, I was surprised to fine in drawing 13 amps or more at start up and between 8 and 6 amps in steady operation.· This seems way to much.· Also, the resistance measurement registered infinite.· I guess some brush motors just won't provide the information.
So, what I am wondering is how does one locate and select a good motor?· I have about 10 out of CD drives that I can directly drive a wheel in a tricycle with the single wheell providing the power or I can continue to fool around with the Tamiya gear box and swap out other 'standard hobby motors'.· I could even disassemble a hobby motor and rewind it to enhance performance.
What I do know is that my solar cells cannot provide steady state 10 amps and maybe only 1 amp tops.· So I am looking at some kind of Solar Engine that charges a bank of·super capacitors and then gives a pulse of energy.
After that is all done, I am considering having an SX20 operated from a 3 volt button battery become the Solar Engine in a programible format.
But first I need to get the motor right.· Eventually, I was thinking of having a Solar Line Follower as a contest format.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
PLEASE CONSIDER the following:
Do you want a quickly operational black box solution or the knowledge included therein?······
···················· Tropically,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan
Comments
I wonder if some of the folks over at·Solarbotics might have some good input on this question or maybe David Cook over at Robot Room? Cook had a continously running solar powered bot on his site that I was looking at the other day - XS Boost, Chef's Salad Solar Robot.
The measurements don't sound right to me either.
By the way, I scavanged some neat motors recently from some·Oral·B·toothbrushes. Some like pager·motors with vibration, others were bigger with a drive wheel.
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Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
Post Edited (Whit) : 2/22/2008 1:06:26 PM GMT
I am looking for insights into general guidelines for the DIY that finds an unmarked DC motor and wants to fool with it. Basically, a junkbot approach.
I did locate another 3v hobby motor that gave me a resistance reading of 3.5 ohms.
I have better DC motors canabalized from a bunch of old CD plays and they are either about 50 ohms or 150 ohms. They are higher quality of bearings and construction details.
Pager motors are quite handy if you really want to work at the lowest power and I have some that I removed the asymetrical counter weight. It is a bit tedious to remove. You have to file one side until you just reach the motor shaft, then it will pull off.
The only problem with pager motors is that they are extremely small for motor mounts. I use one half of a fuse clip to hold one.
I really like Tamiya's system and the fact that they provide wheels, gearboxes, and motors for single axel drive or two motors for differential drive. I just think that what I refer to as a 'hobby motor' is a throw back to the 1950s. It has been the same size and shape in toy cars as long as I've been able to remember. We have new magnets, better brushes, micro bearings, and so on. With the electronics, I want to optimize.
The hobby store that I frequent does have some 'high performance' motors in the same format, but they tend to be quite expense for what they offer. I'll take another look at them.
I also have a source for battery powered tape cassette replacement motors of various voltage, but rotation is designated for only one direction. I think they put a diode inside to prevent have motors pull on the tape from both directions if there was a switching failure.
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
PLEASE CONSIDER the following:
Do you want a quickly operational black box solution or the knowledge included therein?······