Modification to an ebay sourced electronic controller

[Dennis RaynerParticipant @dennisrayner52782]

I've bought one of these controllers:

http://www.ebay.co.uk/itm/10-50V-60A-DC-Motor-Speed-Control-PWM-HHO-RC-Controller-12V-24V-48V-3000W-MAX-/291548215661?hash=item43e1a0b96d

which comes with a potentiometer who's track measures 90K. I want to fit a 4QD "dead mans handle" pot which has a 10K track. Would any of our electronic experts like to suggest what's likely to be the outcome of a straight swap?

Many thanks

[Dennis RaynerParticipant @dennisrayner52782]

[John RuddParticipant @johnrudd16576]

For starters, the speed control is likely to be very sensitive……you are cramming 0-100% speed from a 90k pot into a 10k version….without the schematic, its difficult to determine any other impact on the circuitry, ie current…..if the pot is part of a potential divider, then the current will change…..

Well thats my take on it, others may have something different to add…..

Cant you get a 100k pot with the requisite feature you require? Would be better than a 10k pot……

[john fletcher 1Participant @johnfletcher1]

It would easier to buy a 100k linear potentiometer and careful remove the existing one from the circuit board and solder the new 100k in place. If you are mounting the thing remote you will need a length of 3 core flex from the board to the hand set. I did a similar thing for a friends grand children electric car, made from a scrap disable buggy. John

[Michael GilliganParticipant @michaelgilligan61133]

Posted by john fletcher 1 on 28/05/2017 16:31:37:

It would easier to buy a 100k linear potentiometer and careful remove the existing one from the circuit board and solder the new 100k in place. …

.

John,

Whilst I agree with your general advice … It appears to be even simpler than that ^^^ : **LINK**

http://www.ebay.co.uk/itm/10-50V-60A-DC-Motor-Speed-Control-PWM-HHO-RC-Controller-12V-24V-48V-3000W-MAX-/291548215661?hash=item43e1a0b96d

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Can't really tell without a circuit diagram. If you don't mind the risk of burning out the pot and/or the electronics you could try it and see. Normally I wouldn't risk it – 90k and 10k are an order of magnitude apart. However, as a new pot is only about £3 and the electronics £12, busting them both would hardly break the bank.

One other potential complication. Some of the 4QD pots have a 50° travel rather than the usual 270°. I'm not sure what could be done if the dead man's handle needs a 90k 50° component; I've never seen one advertised.

[Dennis RaynerParticipant @dennisrayner52782]

As has been pointed out, the existing pot is connected to the circuit board by a micro 3 pin plug so there is no physical problem in changing it. The thing is that I have experience of the 4QD spring return 50 degree movement pot (they call it a throttle) and it works a treat as a Dead Mans handle which is especially useful (and safe) with children driving on my garden railway. 4QD only offer it in 10K form and I think I might give them a ring onTuesday to see if they are able to offer it in 90K (or more likely 100K)

Thanks for all the responses.

[Neil WyattModerator @neilwyatt]

As the pot has three wires instead of 2 it is being used to generate a voltage rather than a resistance so you may well find that its actual value is relatively unimportant, although it may impact on max and minimum values.

[Martin ConnellyParticipant @martinconnelly55370]

If you have no joy from the suppliers you could try a 470k pot and modify it with some conductive paint on the track to give a 90k range over about 50 degrees.

Martin C

[MuzzerParticipant @muzzer]

As Neil says, it will doubtless work with almost any value pot, within reason. Sounds as if the supplied one is nominal 100k but 10k is still going to draw only a minimal current.

Murray

[BazyleParticipant @bazyle]

I see a different problem. The circuit board potentiometer is using the full 270 degrees of the pot to give a range of control voltage form roughly 0-max. However the 4QD is probably only using a small part of the range of a standard pot so only giving a small part of the voltage range. They will have designed their own controller to work with this.

[BazyleParticipant @bazyle]

ah, the 4QD is a special

By the way I suggest adding a bit of forced air cooling and a way to stop the kids slamming it into reverse. Perhaps a simulated steam screw reverser that will take a while for them to wind over to the opposite direction.

 

Edited By Bazyle on 28/05/2017 20:42:02

[Dennis RaynerParticipant @dennisrayner52782]

Well this has proved to be a lot more complicated than I expected! Thanks for all the thought provoking comment which has taken me to the conclusion that (adhering to the KISS philosophy) I should start off by using the 270 degree pot. supplied with the cotroller. It was cheap and, if it doesn't prove satisfactory in my application, I will consider going down the full 4QD route.

Thanks again to all.

[SillyOldDufferModerator @sillyoldduffer]

Another solution would be to make a Dead Man's handle to suit. Bit of a faff, but making a 5:1 gear / spring / handle assembly for a 270° pot isn't impossible.

[Ian S CParticipant @iansc]

If you are getting a new pot, you better sort out if you need a linear, or log type.

Ian S C

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