How can I wire a potentiometer into a motor circuit ? Let's say I have a 12 VDC battery, controlling a motor. Is there a way to wire the potentiometer into the circuit without getting into electronics ?
Potentiometers
- Thread starter Madman
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It's merely a variable resistor. You can wire it how you would wire any resistor, except since it has 3 terminals, it's like two resistors sharing a leg in the middle, and the resistance of each of those resistors changes depending on how you adjust it. You don't have to use all three terminals, but make sure you use the middle terminal so that the adjustments will work.
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Not a fan of this idea..
There is a reason tram resistor packs are on the roof, and no-one has asked what voltage battery, and what the motor current is going to be?
'Rheostats' tend to be large, and wire-wound, for a reason.
By the time you have sourced, and paid, for a wire-wound, decent wattage potentiometer, you could get a Chinese speed controller for less.
There is a reason tram resistor packs are on the roof, and no-one has asked what voltage battery, and what the motor current is going to be?
'Rheostats' tend to be large, and wire-wound, for a reason.
By the time you have sourced, and paid, for a wire-wound, decent wattage potentiometer, you could get a Chinese speed controller for less.
IP Engineering use a simple pot controller, and I never managed to make 'em work, usually for the questions you just asked
The theory's fine, but ....................
Using a potentiometer as a rheostat for simple motor control.
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The add wire, if the wiper ever loses contact with the resistive strip inside the potentiometer, this connection ensures the circuit does not completely open, that there will still be a resistive path to the motor. Old potentiometers tend to suffer from intermittent losses of contact between the wiper and the resistive strip, and if a circuit cannot tolerate the complete loss of continuity (infinite resistance) created by this condition, that “extra” wire provides a measure of protection by maintaining circuit continuity.
Should add this an extremely inefficient method of motor control, surplus voltage is wasted as heat.
If you could elucidate further, an off the shelf, ready made unit, may serve your purpose better.............
This is an improvement, minimum electronics required!
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Off the shelf solutions....
Add DPDT switch for reversing
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View attachment 253209
The following two, used on many numerous occasions, just need to add a DPDT switch for reversing.
The second one listed is in daily use as part of the control system on the two analogue display layouts, running 24/7 365 days a year.
6v-28v DC 3a PWM Motor Speed Regulator Switch Controller Pulse Width Modula L2r5 for sale online | eBay
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Then there is this mega jobbie....
6-90V 15A DC Motor Speed Controller Pulse Width PWM Speed Regulator Switch UK | eBay
PWM frequency: 16kHz. The overload and short circuit protecting current is 15A. Can adjust the speed by the external 0-5V signal. Duty Cycle adjustable: 0-100%. The maximum output power: 1000W. The maximum continuous output current :10A.www.ebay.co.uk
Several of these have been built, including the option for Linear Control, out for testing with G Scalers around the South West, can be found via this thread post #1218.
Possible (subject to feedback) could be the control system of choice for the Analogue Layout at the Exeter Garden Rail Show in October this year.
Electronic trickery, Bluetooth and WiFi versions are also out and about for testing.........................
I've been messing with building my own circuitry for a Playmobil Atlas crane loco. I usually use G Scale Graphics Railboss to operate my motive power, but at $200.00 plus, I thought I'd go on the cheap with this project.
I have the largest motor speed control you pictured and was trying to find a place for it, along with a receiver and battery. I thought of placing it on the roof and building a shroud to cover it, but it detracts from the appearance a bit too much. Thank you for showing one of the smaller motor speed controls. I will definitely get a hold of one for this project.
Thanks Phil, I was hoping someone would speak up about figuring the wattage needed of the pot to handle a motor.
1 amp at 12 volts is 12 watts.... most of the pots that are about 1" in diameter are only 2 watts, sometimes 5 watts, i.e. you could literally burn one up on a small motor with very little voltage.
Greg
1 amp at 12 volts is 12 watts.... most of the pots that are about 1" in diameter are only 2 watts, sometimes 5 watts, i.e. you could literally burn one up on a small motor with very little voltage.
Greg
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I dunno - is it? There is a small IR on it. It came from the UK so you might know better than me.Is that an 'International Rescue' logo, I see on the side of that loco?
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Whoever built it.. Must have used it as a 'Thunderbird'? 
Thunderbird = Loco's manned at various places, to go drag a failed unit to safety..
Thunderbird = Loco's manned at various places, to go drag a failed unit to safety..
D
