kwi Posted November 11, 2015 Share Posted November 11, 2015 After pouring through all the manuals and searching on here with no luck was hoping someone could answer me this.I am wanting to run a 3v DC motor from a port on an r8427 (Scenic element on the table.)Is there anyway to do this just on the CVs or will I need a resistance circuit? Link to comment Share on other sites More sharing options...
2e0dtoeric Posted November 11, 2015 Share Posted November 11, 2015 You would find it simpler to run the device from a 3v supply, ie two D cells, with it's own feed and switch.If you try to run it from a decoder that delivers 12v, you will either fry the motor or the decoder. Link to comment Share on other sites More sharing options...
kwi Posted November 11, 2015 Author Share Posted November 11, 2015 You would find it simpler to run the device from a 3v supply, ie two D cells, with it's own feed and switch.If you try to run it from a decoder that delivers 12v, you will either fry the motor or the decoder.Agreed it would be simpler, and on my N gauge dc setup that's what I would do, but I am wanting to run everything from the one controller. (eLink and RM.) Link to comment Share on other sites More sharing options...
Rog RJ Posted November 11, 2015 Share Posted November 11, 2015 The decoder can be set to give a continuous output by altering CVs. See the instructions for the decoder https://www.hornby.com/uk-en/downloads/view/download/item/150 You will need to reduce the output voltage to suit your motor as it normally supplies about 12volts. Also make sure your motor doesn't take too much current or you will burn out the decoder. Far simpler IMHO to have a separate switch. Link to comment Share on other sites More sharing options...
Hairy Posted November 11, 2015 Share Posted November 11, 2015 I use a latching relay controlled by the decoder to switch a seperate power supply for lighting. Just wire the relay up as you would wire a point motor/solenoid. I seem to remember a wiring diagram on here somewhere showing it. Link to comment Share on other sites More sharing options...
kwi Posted November 11, 2015 Author Share Posted November 11, 2015 I use a latching relay controlled by the decoder to switch a seperate power supply for lighting. Just wire the relay up as you would wire a point motor/solenoid. I seem to remember a wiring diagram on here somewhere showing it. Cheers, just sort of hit on that idea after Rogs comment, have loads of spare solenoid motors so just need to get a switch unit to stick on one. (And a seperate Power supply.) Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 Why not use this DC to DC convertor ready made electronic solid state product to convert the output of the R8247 to 3 volts DC. See top item on the Hyperlinked page..The output of the R8247 will need to be configured for 'always on' rather than 'pulse' output. The 'C' terminal on the R8247 will connect to the +ve DC input on the above device and either the '+' or '-' terminal on the R8247 will connect to the -ve DC input on the above device. When the relevant R8247 port is energised, the output of the above device gives a +3 VDC output. Link to comment Share on other sites More sharing options...
96RAF Posted November 12, 2015 Share Posted November 12, 2015 @kwiso you plan to use the acc decoder to fire a spare solenoid which will activate an attached switch to run your motor.why not fire the acc decoder pulse into the coil of a latching relay that will use its main contacts to run your motor.thats how I do my points So that I can have manual and DCC control of these. Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 KWIPS - Forgot to add in my previous reply. The solid state electronic solution I offered in my previous reply, negates the need to have a separate 3 VDC power supply, as the 3 volt output is generated by the circuit board from the higher input voltage. Link to comment Share on other sites More sharing options...
Flashbang Posted November 12, 2015 Share Posted November 12, 2015 Or one of these for £1.88 post included from China via ebay.... (I obtianed 3 at and all work great)...http://i190.photobucket.com/albums/z311/Flash_bang/IMG_1059_zpsh5vxkq59.jpg ebay voltage regulatorThe LED voltage display really helps with setting up the correct output volts, it can also show input volts too. Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 Nice one Flashbang. I couldn't even buy the components to make my own for that price. I've just ordered a couple myself for the toolbox. Looks like a nice flexible product for anybody interested in electronics as a secondary hobby. Link to comment Share on other sites More sharing options...
Flashbang Posted November 12, 2015 Share Posted November 12, 2015 Yeah, I often buy 'odd bits' from ebay China supplies. Timers, voltage regulators both fixed and variable etc. :-) I dont mind waiting for a couple of weeks for the items to arrive at the silly prices thay sell them for. So far I've not had any that havent done what they say they should do! Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 My last China purchase, prior to this one of course, was one of those USB voltage testers. Plug it into a free or in use USB port and it monitors the voltage and current drawn on a LCD display. I'm sure you've seen them..I did consider posting a simple regulator circuit here with just three components. A 3 pin regulator chip plus two stability capacitors instead of the ready made item I eventually posted. The home brewed circuit would have cost about £1.15 to make. Decided against it as most on here are reluctant to get a soldering iron out and work with electronics. Shame really, as there is so much you can build yourself for model railways at a fraction of the cost of shop bought products. Link to comment Share on other sites More sharing options...
kwi Posted November 12, 2015 Author Share Posted November 12, 2015 Flashbang, great find, and exactly what I was thinking along, well actually a bit more complicated than what I was thinking about, but at that price a bit of a no brainer.Chrissaf, I am not afraid to do a bit of soldering, quite enjoy it actually and my original question was could I drop the output from the decoder using CVs or would I need an additional circuit. If you could post the diagram out of curiosities sake it would be appreciated. Though it's true you can often find ready made solutions cheaper than you can buy components for these days which is something that has probably harmed the diy side of the hobby with people expecting a more 'plug and play' way of doing things. Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 KWI, I'll post the diagram later today. Because of the image it will need to be authorised by Admin before it will appear. Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 KWI,The circuit diagram you requested me to provide. The extra odd 0.3 of a volt on the output shouldn't impact on the operation of the motor..Component links:IC RegulatorCapacitors./media/tinymce_upload/68bfa385093c0d5f124d43347189071f.jpg Link to comment Share on other sites More sharing options...
Chrissaf Posted November 12, 2015 Share Posted November 12, 2015 KWI, I see my diagram has been authorised and posted. If you right click the image, you should get (subject to browser being used) an option to see and/or save a full screen version making the image bigger and hopefully clearer. Link to comment Share on other sites More sharing options...
kwi Posted November 12, 2015 Author Share Posted November 12, 2015 Cheers Chris, it's clear as displayed and is as simple as I imagined, and IMHO simpler than having a seperate circuit. (20+ Years since I last really done any electronics work.) The motor hasn't any real load barring gearbox resistance and then a set of windmill sails, though I will test it to make sure.Thanks again. Link to comment Share on other sites More sharing options...
choralc Posted November 12, 2015 Share Posted November 12, 2015 So, Flashbang, to clarify for me with that doo-dad you linked to I would put the common and either the red or green into the input set the decoder port to continuous and connect what-ever to the output after configuring a suitable output voltage? e.g a small motor, station lighting Link to comment Share on other sites More sharing options...
Chrissaf Posted November 13, 2015 Share Posted November 13, 2015 In Flasbang's absence. In answer to your question Yes, but with the following limitation. Be careful about how much current you want to draw through this device. You used 'station' lighting as an example. If you got carried away with adding lights (even assuming LED lights) the amount of current will steadily increase, you may exceed the safe limit of what the accessory decoder can safely deliver..Assuming Hornby R8247, despite looking I have been unable to find definitive documentation that states the maximum port current the R8247 will provide. When being used as a solenoid pulse device, the high solenoid current is being delivered from the internal CDU. The 'always on' current available will be far lower than that, as the internal CDU offers no benefit in that scenario..A normal loco decoder function output is typically 100mA. So one would expect the R8247 to deliver at least that, maybe twice that. Without seeing the technical spec in writing I would not want to risk damaging the R8247 by driving the output too hard. I think it would be safe to assume 100mA, maybe a little more being that the R8247 is significantly bigger than a loco decoder, but don't assume masses of current being available..If anybody has seen a written spec stating max port 'always on' output current of a R8247, I would like to know !!.I seem to have a very faint recollection of seeing a figure of 800mA being mentioned, but that may be just my mind playing tricks on me. And that figure, if accurate, is most likely the cumulative total for all four decoder ports. Link to comment Share on other sites More sharing options...
Fishmanoz Posted November 13, 2015 Share Posted November 13, 2015 I think I've seen 100mA Chris, but not sure. Link to comment Share on other sites More sharing options...
Fishmanoz Posted November 13, 2015 Share Posted November 13, 2015 I just tried to download the manual too to check what's in there and it wouldn't. Link to comment Share on other sites More sharing options...
Rog RJ Posted November 13, 2015 Share Posted November 13, 2015 There is some information about the R8247 power output capacity in my reply on this page https://www.hornby.com/uk-en/forum/post/view/topic_id/6682/?p=1 Unfortunately the link to the original reply from customer care doesn't work. Link to comment Share on other sites More sharing options...
kwi Posted November 13, 2015 Author Share Posted November 13, 2015 "The R8247 Point and Accessory Controller (PAD) can in total sink/source approximately 240mA. This is shared; this could be all ports turned continually on drawing a total of 240mA, or a single port turned on drawing approximately 240mA."From HCC.Though you think it would be in the manual. Link to comment Share on other sites More sharing options...
choralc Posted November 13, 2015 Share Posted November 13, 2015 Hmmm quite limiting I would have thought but still a useful tool for connecting to your DCC controller and with RM to include in a program Link to comment Share on other sites More sharing options...
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