(Login flyer103) HyperScale Forums from IP address 162.39.196.21
Hi Folks,
I'm building the old Revell 1/32 Corsair and I want to install a small electric motor to turn the prop.
I'm not sure of the specs of the motor but on a single AA cell (1.5v) it turns the kit prop very nicely, and about as fast as I would want it to go. But it would be nice to be able to slow it down. I know this can be done with resistors or rheostats, but's I've never installed these.
If anyone has any suggestions I'd love to hear them.
...often slow to respond to requests by users to do anything (like posting a response). We tend to think the site has frozen up and hit the "post your response" button again (and again) which results in multiple posts. Take you time, and wait for the old technology to catch up to your wishes - it ain't you, it's the system we're on.
For all intents & purposes a rheostat is an adjustable resistor. You can put one in-line with the circuit.... best bet is to look into basic electronics and "do it yourself" sites. It's not that difficult, actually.
You can simply connect an adjustable resistor (a potentiometer, or "pot" in electronics parlance) to vary the current going to the motor. This would be a very crude method, but it would work. One drawback is that inevitably some of the power would be dissipated into heat on the resistor. For a typical 1.5V DC motor that might draw 30-50mA currents; something like a 25 Ohm, 2-3W rheostat should work.
The "right" way to do DC motor speed control in a setting like this is through PWM (pulse width modulation). PWM involves applying "pulses" to the motor, i.e. turning the motor on-and-off many times a second to adjust its effective speed. This is how almost all DC motor speed control is done in real systems, but it requires a dedicated circuit and/or microcontroller.
If this is a quick build to sit on a shelf, and you would only turn on the motor once in a while, anything more complex than a simple potentiometer might be overkill. But if this is a model that you would display in a museum or exhibit setting long-term; I personally would have used a simple Arduino microcontroller board-based solution. It would only cost around $10 (search for "Arduino Mini Pro" on Ebay) and perhaps 15 minutes of programming. It would be a good excuse to get started with simple microcontroller programming projects, too.
KursadA
CaracalModels
www.caracalmodels.com
This message has been edited by KursadA from IP address 163.181.251.103 on Apr 4, 2012 2:33 PM This message has been edited by KursadA from IP address 163.181.251.103 on Apr 4, 2012 2:25 PM
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