hartleymartin Posted August 14, 2013 Share Posted August 14, 2013 Is there any reason that one of these PWM controllers off ebay should not be used on model railways? I am operating O gauge locomotives usually fitted with Mashima 1833 or similar sized motors. http://www.ebay.com.au/itm/400506553335 Link to post Share on other sites More sharing options...
Miss Prism Posted August 14, 2013 Share Posted August 14, 2013 25KHz output frequency for six dollars? I don't think so. Link to post Share on other sites More sharing options...
raymw Posted August 14, 2013 Share Posted August 14, 2013 Hi Martin, Looks OK to me - about the right price for the few components needed. If it is no good, then Paypal will be on your side - usually against the seller. You'll need a reversing switch on the op, and maybe add a resistor in series with the pot to get it to stop the motor. It looks as if they've even put a diode on the ip, to protect it if you connect the power supply wrong way round. hth Best wishes, Ray Link to post Share on other sites More sharing options...
Crosland Posted August 15, 2013 Share Posted August 15, 2013 Is there any reason that one of these PWM controllers off ebay should not be used on model railways? I think you wil find it will not go down to zero, but they make good mini drill controllers. Andrew Link to post Share on other sites More sharing options...
PatB Posted August 15, 2013 Share Posted August 15, 2013 Don't see why not. There's nothing magical about an 1833 can motor so I can't see it doing any harm. The maximum current I've measured from a Mashima 1833 was ~1A with the shaft locked so there's plenty of current capacity there. Link to post Share on other sites More sharing options...
shortliner Posted August 15, 2013 Share Posted August 15, 2013 $30AUD for postage to UK stuffs the price up somewhat though! It is only free post to Oz Link to post Share on other sites More sharing options...
Arthur Posted August 15, 2013 Share Posted August 15, 2013 A search on eBay.co.uk under 'motor driver motor speed' shows them for £3.89 post free. Looks like the same one. Link to post Share on other sites More sharing options...
Suzie Posted August 15, 2013 Share Posted August 15, 2013 It looks remarkably similar in design to a 20KHz PWM controller I made a long while ago that demagnetised most of my locos, especially the 009 ones with 'N' gauge mechanisms. If it is based on a 555 timer (which looks likely) there is the possibility that it might not turn off completely, but it should be possible to get it pretty close to off. Link to post Share on other sites More sharing options...
Suzie Posted August 15, 2013 Share Posted August 15, 2013 Perhaps this one is more suitable with a reversing switch included and free postage. Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted August 15, 2013 RMweb Premium Share Posted August 15, 2013 $30AUD for postage to UK stuffs the price up somewhat though! It is only free post to Oz The item is located in Hong Kong, but they exclude HK as a destination! Link to post Share on other sites More sharing options...
Crosland Posted August 15, 2013 Share Posted August 15, 2013 It looks remarkably similar in design to a 20KHz PWM controller I made a long while ago that demagnetised most of my locos, especially the 009 ones with 'N' gauge mechanisms. If it is based on a 555 timer (which looks likely) there is the possibility that it might not turn off completely, but it should be possible to get it pretty close to off. MIne has the part numbers removed, but it's easy to figure out from the PCB layout that it is a 555. Andrew Link to post Share on other sites More sharing options...
hartleymartin Posted August 16, 2013 Author Share Posted August 16, 2013 I'll be interested to see what the minimum or "zero setting" is like on this controller. If I use a DPDT switch, it will have a centre-off position anyway. I can always add a resistor to the output if need be.Years ago I bought something marketed as a 12V PWM motor controller kit from Dick Smith Electronics. Destroyed some components. Got an electrician friend to build and test another one. Put it safely aside somewhere about 5 years ago and have not seen it since! Link to post Share on other sites More sharing options...
PatB Posted August 16, 2013 Share Posted August 16, 2013 I'll be interested to see what the minimum or "zero setting" is like on this controller. If I use a DPDT switch, it will have a centre-off position anyway. I can always add a resistor to the output if need be. Years ago I bought something marketed as a 12V PWM motor controller kit from Dick Smith Electronics. Destroyed some components. Got an electrician friend to build and test another one. Put it safely aside somewhere about 5 years ago and have not seen it since! A while ago I built the Dick Smith PWM model railway controller. I haven't ever used it on a layout but it sems to give very good, smooth slow running with various locos on a yard or two of track on the kitchen table, including a Mashima 1833 equipped beastie. It cost a bit more than $7 though. IIRC it was about $40. Link to post Share on other sites More sharing options...
Crosland Posted August 16, 2013 Share Posted August 16, 2013 I'll be interested to see what the minimum or "zero setting" is like on this controller. If I use a DPDT switch, it will have a centre-off position anyway. I can always add a resistor to the output if need be. Using a resistor is exactly the wrong way to compensate for controller output. You will end up with poor regulation due to the voltage drop acros the resistor varying with the load. Just get/make a decent controler designed for the job. Andrew Link to post Share on other sites More sharing options...
CourthsVeil Posted August 16, 2013 Share Posted August 16, 2013 $30AUD for postage to UK stuffs the price up somewhat though! It is only free post to Oz Silly: $ 30 to the UK, free to Denmark, no delivery at all to Germany... Verrry silly, indeeed! But even if they would send it to Germany, I would be cautious to use it. There are a lot of alternatives! Link to post Share on other sites More sharing options...
hartleymartin Posted August 17, 2013 Author Share Posted August 17, 2013 Stupid me, I meant to say to add a resistor in series with the potentiometer (variable resistor) to ensure that it actually gives a "zero" output. Seeing as I have put aside several power adaptors (never throwing away anything that might be useful), I need only add the afore-mentioned resistor, a DPDT switch and wire up the power pack and I should have a decent, if basic PWM controller. Link to post Share on other sites More sharing options...
hartleymartin Posted January 28, 2014 Author Share Posted January 28, 2014 I've wired it up and tested it. Aside from a couple of dry solder joints (poor workmanship) it actually works just fine. However, if I ever take my little Inglenook layout to exhibitions, I'd want a spare controller as a just-in-case. Link to post Share on other sites More sharing options...
hartleymartin Posted January 28, 2014 Author Share Posted January 28, 2014 I should say that I tested it using a Hornby J94 and Terrier. Link to post Share on other sites More sharing options...
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