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Seeking advice on DC motor speed control

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John Rudd:
The way I would do it is as follows......

Connect the speedo up to a 100 watt light bulb in place of the motor.
Connect a voltmeter across the bulb.
Now, add another pot by connecting it in series with the one supplied.
Turn both pots to max,then adjust the second pot until the meter reads 170-180v dc....
Switch off and remove your second pot,measure the resistance, that is the value needed....should it be an odd value then go up to the next preferred value available.....


Pm sent.....

NormanV:
Thanks John, that sounds straightforward enough. Only problem that I can see is getting hold of a 100 watt bulb!
Norman

philf:

--- Quote from: NormanV on January 11, 2014, 10:13:33 AM ---What size resistor?
Phil, as to the VAT on the service(?) from Royal Mail I had a similar problem in a previous life. I used to be a wine maker and there was excise duty to be paid on it and then VAT on the duty! Taxing the taxes, they do it on petrol also.

--- End quote ---

Just got back from a walk and see that John's beaten me to it. He's given a more than adequate reply.

I have noticed that some Chinese sellers put a lower than paid for value on the customs slip so hopefully you'll get away with it.

I found a DC speed control whilst tidying my workshop but with no documentation and no identifying marks. It's gone in the bin. Permanent magnet brushed motors seem to have plenty of torque at low speeds which makes them very suitable for small machine tools. I use them on my vertical head on my Aciera Mill and on my watchmakers lathe.

Good luck.

Phil.

Bluechip:

--- Quote from: NormanV on January 11, 2014, 10:44:29 AM ---Thanks John, that sounds straightforward enough. Only problem that I can see is getting hold of a 100 watt bulb!
Norman

--- End quote ---

100W RS lamps are still available 'cept the buggers are often E27 rather than Bayonet Cap...  :bang:  :bang:

http://cpc.farnell.com/ge-lighting/00091227/rough-service-100w-es-200-250v/dp/LP02281?in_merch=Products From This Range


OK to use 2 x 60W in parallel.

Dave

John Swift:
Hi Norman

depending on where you live try
http://www.bmstores.co.uk/products/4-pack-100w-bulbs-283188
or
http://www.wilko.com/light-bulbs/general-electric-heavy-duty-light-bulb-60w-x-2/invt/0244465

  John

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