ThePurplePrimer Posted April 7, 2014 Share Posted April 7, 2014 Hi guys I am afraid this is going to be one of those silly newbie questions again Just got a DCC Supplies Cobalt point motor and test installed it and wired it up ( powered by 9 volts DC ) It all works fine and throws the pointwork but after it has switched the point it just sits there slightly humming or buzzing continuously - its not very loud but I am not sure this is correct. Is it meant to be like that ? If it matters I am operating it with a DPDT switch Link to post Share on other sites More sharing options...
phixer64 Posted April 7, 2014 Share Posted April 7, 2014 Try fitting a CDU, otherwise, you might burn out the motor http://www.gaugemaster.com/instructions/cdu.pdf Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 7, 2014 RMweb Premium Share Posted April 7, 2014 Try fitting a CDU, otherwise, you might burn out the motor http://www.gaugemaster.com/instructions/cdu.pdf What? It's a stall motor! Do not use a CDU Keith Link to post Share on other sites More sharing options...
ThePurplePrimer Posted April 7, 2014 Author Share Posted April 7, 2014 Yes it's a stall motor so NO cdu is fitted Maybe Phixer has shares in dcc supplies :-) Link to post Share on other sites More sharing options...
Brian Posted April 7, 2014 Share Posted April 7, 2014 Hi The humming/buzzing you can hear will be most likely from the motor. It sits in a stall state and draws a small current from the supply. Your DPDT switch is needed to provide the polarity swap to allow the motor to move to the other position. As for the CDU recommendation please ignore it. CDUs are used with solenoid point motors not stall types. Link to post Share on other sites More sharing options...
ThePurplePrimer Posted April 7, 2014 Author Share Posted April 7, 2014 Thanks Brian for reassuring PS - I have your book and have found it very useful and easy to understand - worth every penny Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 7, 2014 RMweb Premium Share Posted April 7, 2014 Hi guys I am afraid this is going to be one of those silly newbie questions again Just got a DCC Supplies Cobalt point motor and test installed it and wired it up ( powered by 9 volts DC ) It all works fine and throws the pointwork but after it has switched the point it just sits there slightly humming or buzzing continuously - its not very loud but I am not sure this is correct. Is it meant to be like that ? If it matters I am operating it with a DPDT switch Try running it off a 9v battery (PP3) and check that it is silent at the end of the travel. If it is, the hum/buzz is being introduced by the supply you are using. Is it fully smoothed or is it raw DC? Keith Link to post Share on other sites More sharing options...
ThePurplePrimer Posted April 7, 2014 Author Share Posted April 7, 2014 Hi Keith To be honest I don't actually know if it's fully smoothed ( how do I check ? )- it's running off a Gaugemaster Combo dc controller that I set using a voltmeter to 9 volts Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 7, 2014 RMweb Premium Share Posted April 7, 2014 Hi Keith To be honest I don't actually know if it's fully smoothed ( how do I check ? )- it's running off a Gaugemaster Combo dc controller that I set using a voltmeter to 9 volts I don't know anything about that particular controller so I can't comment on what it's like. Maybe someone else who is familiar with it might chip in with some more information. Some controllers use a DC output that is just rectified AC and will have a large amount of ripple (remnants of the AC) on the DC voltage. This can cause buzzing/humming in some cases. (Some small DC motors however actually can work better on unsmoothed DC!) Other controllers smooth and regulate the rectified DC and will produce a much cleaner DC voltage, hence little or no chance of buzzing! Keith EDIT My suggestion about trying it with a 9V battery (pure DC!) will probably prove that the supply is to blame and the Cobalt is silent at the end of it's travel. They only draw 15-20mA so providing you don't leave the battery connected permanently it will be fine to use it just to test it. Link to post Share on other sites More sharing options...
RMweb Premium t-b-g Posted April 7, 2014 RMweb Premium Share Posted April 7, 2014 Was the controller set at 9V with the point motor in the circuit? If it was, then it may be worth setting it again with no point motor attached. The output from a controller under no load can be surprisingly high if it has no loading on it (I have been measuring a so called 12v DC supply at 18v this afternoon). I have heard of this problem with Cobalt motors being due to an over high power supply voltage. It may be worth talking to the suppliers of the motors for some advice. At least one is aware of such problems. One Cobalt user told me that he had the problem, talked to his supplier and they recommended a different transformer that cured the problem completely. Unfortunately the conversation was at an exhibition and I cannot recall any more details than that. Tony Link to post Share on other sites More sharing options...
Brian Posted April 8, 2014 Share Posted April 8, 2014 Ah, so its not a pure or regulated dc supply which is what my original replay was based upon. The controller may be PWM or just not smoothed dc. Do try as suggested using a PP3 battery as a test on one that is buzzing when the controller was feeding it. If it goes quiet or quieter then you really need to use a better form of dc. If 9 volts is your chosen voltage and its becomes quieter on a battery, then consider obtaining a 9 volt regulated power supply, like this example http://www.ebay.co.uk/itm/9-Volt-DC-Power-Supply-9v-Regulated-PSU-Max-600mA-0-6A-/290614964357?pt=UK_Computing_PowerSupplies_EH&hash=item43aa007085 This is able to feed approx 17 to 20 Cobalts when stalled Extract from the DCC Concepts Cobalt manual..... Rather than an old train-set transformers DC output which is generally not well rectified, we strongly recommend that you use a better quality regulated DC “wall wart” type plug pack. Edited to correct typo (Twice!). Link to post Share on other sites More sharing options...
ThePurplePrimer Posted April 8, 2014 Author Share Posted April 8, 2014 I just tested with a 9v battery and it looks like you were right Sadly this was not quite as scientific as I might like as the battery is old but reads at 8.9v The battery easily moves the motor and the pointwork and holds it in position - and all with no noise, no buzz or hum once it has reach full travel and is stalled Thanks for the help - now need to buy a proper power supply as suggested by Brian Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 8, 2014 RMweb Premium Share Posted April 8, 2014 Thanks for the help - now need to buy a proper power supply as suggested by Brian As well as E-bay have a look at your local Maplins (If you have one) Something like this: http://www.maplin.co.uk/p/maplin-6w-switched-mode-acdc-fixed-voltage-9v-power-supply-l67bq Slightly more expensive.(icludes a choice of tips - but probably not needed) Easier to complain if you have a problem with it! Keith Link to post Share on other sites More sharing options...
phixer64 Posted April 8, 2014 Share Posted April 8, 2014 Sorry folks, I've mis-read the post. Link to post Share on other sites More sharing options...
Gm11 Posted April 8, 2014 Share Posted April 8, 2014 You may be able to get some quiet by soldering a ceramic 100nf cap accross it. Not guranteed to help as I dont know the frequency of the noise level, but in general 100nf should help and certainly wont hurt Link to post Share on other sites More sharing options...
RMweb Premium t-b-g Posted April 9, 2014 RMweb Premium Share Posted April 9, 2014 I have been helping fit some Cobalt point motors on a layout and the power supply that had been obtained was one sold by Gaugemaster specifically sold for the Cobalt motors. http://www.amazon.co.uk/Gaugemaster-Mounted-Supply-Cobalt-Motors/dp/B00D3KWPKC It worked very nicely on several motors that were tested on it. Tony Link to post Share on other sites More sharing options...
Gordon H Posted April 10, 2014 Share Posted April 10, 2014 You may be able to get some quiet by soldering a ceramic 100nf cap accross it. Not guranteed to help as I dont know the frequency of the noise level, but in general 100nf should help and certainly wont hurt If it is a buzzing noise, chances are it is going to be at 100Hz as a result of insufficient reservoir capacity on the rectified side, so you would probably need something rather larger than 100nF - probably more like 1000uF. Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 10, 2014 RMweb Premium Share Posted April 10, 2014 If it is a buzzing noise, chances are it is going to be at 100Hz as a result of insufficient reservoir capacity on the rectified side, so you would probably need something rather larger than 100nF - probably more like 1000uF. And it would need to be non polarised - a non starter IMHO. Keith Link to post Share on other sites More sharing options...
ThePurplePrimer Posted April 10, 2014 Author Share Posted April 10, 2014 I have been helping fit some Cobalt point motors on a layout and the power supply that had been obtained was one sold by Gaugemaster specifically sold for the Cobalt motors. http://www.amazon.co.uk/Gaugemaster-Mounted-Supply-Cobalt-Motors/dp/B00D3KWPKC It worked very nicely on several motors that were tested on it. Tony Thanks - have ordered one Link to post Share on other sites More sharing options...
Gm11 Posted April 11, 2014 Share Posted April 11, 2014 And it would need to be non polarised - a non starter IMHO. Keith Or use too electrolytics back to back, I sugested 100nf for high frequency, adding in 2 back to back electrolytics should take care of it lower down. But without being there and scopeing it, its all guess work Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 11, 2014 RMweb Premium Share Posted April 11, 2014 Or use too electrolytics back to back, I sugested 100nf for high frequency, adding in 2 back to back electrolytics should take care of it lower down. But without being there and scopeing it, its all guess work Even more bulk! Unless you connect them before the changeover switch, when a polarised one will do. Getting a suitable power supply as Rob (ThePurplePrimer) is doing is IMHO the only sensible way forward. Keith Link to post Share on other sites More sharing options...
Crosland Posted April 11, 2014 Share Posted April 11, 2014 And it would need to be non polarised - a non starter IMHO. Keith If it's 100Hz buzzing then it's almost certainly rectified AC and an electrolytic will be fine. Andrew Link to post Share on other sites More sharing options...
RMweb Premium melmerby Posted April 12, 2014 RMweb Premium Share Posted April 12, 2014 If it's 100Hz buzzing then it's almost certainly rectified AC and an electrolytic will be fine. Andrew See my previous post I believe the discussion started with a suggestion to connect a cap across the Cobalt, which will have a switched DC voltage to operate it hence my comments Keith Link to post Share on other sites More sharing options...
Gordon H Posted April 14, 2014 Share Posted April 14, 2014 The original mention of a capacitor by Gm11 only mentions connecting across 'it' without saying what 'it' would be. Pretty obvious 'it' should be the power source rather than the driven load in this case as it is the power source that appears to be deficient in its smoothing capabilities. Link to post Share on other sites More sharing options...
ThePurplePrimer Posted April 14, 2014 Author Share Posted April 14, 2014 The Gaugemaster power supply arrived today and as you would suspect it works perfectly. Thanks to everyone for all the help you have provided The wall plug style power supply in the box also comes with a small pcb board with a plug for the supply, an led to let you know its working and some screw style terminals so you can power out to your Cobalt point motors - brilliant BUT - it would have been nice if the pcb had some mounting holes so it could be screwed down safely. There isn't any spare space to drill some and its got a few bumps on the back that would make using double sided tape impractical - need to have a think - I do have one idea but its a bit bodgy and invovles some copper wire and a choc block - yukkk ! Also there are some extra holes on the pcb but the instructions say nothing about what you could use them for ? But in conclusion I am happy with it Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.