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Voltage controlled dc motor controller

Hey all, this is my first post. I'm working on a project where I have an adjustable DC 0-12v 500mA power source which is used to control a model train motor on a miniature railroad. The control board/power source also has speaker outputs for realistic sound effects like engine RPM sounds which increase as the output voltage is increased.

I am working on a much larger backyard, rideable railroad and the train is powered by a 12v 150w 10a DC motor. I am installing an amplifier and speakers and want to use the same control system (built for small trains) for the realistic sound effects. Because it is only designed for low current uses, I need some sort of motor controller which will take the low current 0-12v voltage input, then take power from an external 12v power source and adjust that to control the speed of the larger motor accordingly. If someone can point me in the right direction, I'd appreciate it!

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Reply to
aepifani
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Maybe just a beast of a power amplifier? ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.
Reply to
Jim Thompson

Nope. At first I thought you needed to pass control signals... instead just use your controller as the reference voltage for a buck converter, giving you low dissipation and good efficiency. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142   Skype: Contacts Only  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 

             I'm looking for work... see my website.
Reply to
Jim Thompson

Weird Things can happen if you use a synchronous buck converter, though. If you do motor braking the converter will try to stuff that energy backwards into the battery (because if you trace through a synchronous buck converter backwards, you realize it's a synchronous boost converter).

This is nice up to the current that the battery can accept for charging, but beyond that things can get exciting. If it's a back yard with a long steep slope, things may get exciting in an exploding-battery sort of way.

So you need a resistor and some steering electronics to dump power at appropriate times, or you need to use a converter with a steering diode (and live with the loss of efficiency).

There absolutely positively has to be a motor controller of sufficient capacity for this, that can accept a voltage input for speed control. I'd suggest looking at what's available for electric bike conversions. I've never even seen one, but I suspect that if they've got "throttle" inputs there are at least some that'll take 0-12V (or maybe 0-5V).

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Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com 

I'm looking for work -- see my website!
Reply to
Tim Wescott

I question whether 120 watts is enough for a rideable train, but I'll go with it.

Mikek

Reply to
amdx

Not too many of those that'll do 1 ohm @ 150W @ DC. DC is Bad for audio power amplifiers, which is the fat part of that market.

This sounds more like a PWM sort of thing, with an LPF added before the DC motor.

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Les Cargill
Reply to
Les Cargill

You need more than 150W. Something like this would control\what you need:

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Clifford Heath.

Reply to
Clifford Heath

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