The Mattle Posted January 25, 2015 Share Posted January 25, 2015 Hi all, I've recently purchased a 4-4-0 LMS Compound Loco - R.376. Having taken the tender drive apart to see how easy it would be to convert to DCC, I thought no problem. Curiosity Then got the better of me and I took the body of the main loco and discovered it has a working smoke unit attached. The unit itself was disconnected but after testing appears to work ok. Now my question is... How would I go about converting the loco to DCC and have the smoke unit working ??? I'm fairly competent at basic electrics and soldering. Would i be able to use a standard Hornby decoder mounted in the tender as I'd planned and use the one of the function outputs to control the smokeunit via two small wires running from the tender into the loco ? Or is it going to require something a bit more powerful to cope ?I'm not sure how much current the smokeunit draws running on standard DC as I don't have a standard DC controller, only a Hornby DCC controller. Any help would be much appreciated !!! Link to comment Share on other sites More sharing options...
poliss Posted January 25, 2015 Share Posted January 25, 2015 You'd need to use two of the function outputs to operate the smoke unit, say the purple and green wire with blue as common return.Both functions must be set to constant bright in both directions. Link to comment Share on other sites More sharing options...
The Mattle Posted January 25, 2015 Author Share Posted January 25, 2015 Thanks for the reply, would the standard Hornby decoder be man enough for the job or would I be better of using the Hornby Saphire decoder ? Link to comment Share on other sites More sharing options...
poliss Posted January 25, 2015 Share Posted January 25, 2015 They're 100mA each and the modern Seuthe smoke units draw around 125mA.Probably safer to use the Sapphire who's outputs are 200mA each. Link to comment Share on other sites More sharing options...
The Mattle Posted January 25, 2015 Author Share Posted January 25, 2015 Thankyou for your help, much appreciated. Link to comment Share on other sites More sharing options...
Tee1707818014 Posted January 25, 2015 Share Posted January 25, 2015 This from brian lambert websiteSmoke Units in locos on DCC are possible. Here I would recommend using a small sub miniature 12 volt relay to switch the actual smoke unit On/Off. Power for the unit is derived from the DCC power but by passing the power via the contact of a relay will ensure there is no possible overloading of any Function output of a decoder. Many decoder function outputs are only rated at 100 milliamp while a lot of smoke units require 120 to 200 milliamp to operate. A relay will allow operation without overloading the function output. Operation is... Function 'F1' turned On and this allows the relay to operate and close its contact - Comm to N/O. DCC track voltage is then allowed to pass to the smoke unit. Once smoke operating is ended the 'F1' key is operated and the relay releases opening contacts Comm - N/O.It is wired as per the drawing below..... Link to comment Share on other sites More sharing options...
The son of Triangman Posted January 26, 2015 Share Posted January 26, 2015 A relay is best used. One thing about the Hornby smoke units used in these models and locos like the 28xx 2-8-0m they do tend to melt the chimneys so work will be needed to reduct the current to the minimum required to heat the smoke unit element up to produce smoke, a suitable resistor is a must. Link to comment Share on other sites More sharing options...
96RAF Posted January 26, 2015 Share Posted January 26, 2015 You'd need to use two of the function outputs to operate the smoke unit, say the purple and green wire with blue as common return.Both functions must be set to constant bright in both directions. Green and Purple (F1 & F2 on basic Hornby decoders) when switched on are irrespective of loco direction.However using a relay is preferred to give the decoder any easier and probably longer life. Finding space for even a micro realy may be a problem. Link to comment Share on other sites More sharing options...
The Mattle Posted January 26, 2015 Author Share Posted January 26, 2015 Thanks for the replys guys, i think it would just about be possible to fit a miniature relay inside the loco body. Any ideas what resistance i would need to wire in series with the smoke unit ? Link to comment Share on other sites More sharing options...
96RAF Posted January 26, 2015 Share Posted January 26, 2015 I found this on Model Railroader (American) forum from a guy who installs them for clients:quote /There are several do's and don'ts.1) Most Seuthe units draw over 125 mA. Most function outputs on decoders provide 100-120mA. If you try to directly power the smoke unit through the decoder, you will burn out the assigned function's circuit in a very short time.2.) The best way to provide the on/off function you desire is through a small micro relay switch. That way, you use the decoder function to control the relay and feed track power to the smoke unit through the relay and not the decoder. ESU makes a very good relay switch for this purpose.3) The Seuthe unit will work best at 12-16 volts. I do not recommend trying to reduce the voltage. The unit has to get hot at atomize the smoke oil. If the power is too low, it will simply spit blobs of the oil out the stack.4) Seuthe offers jacketed and non-jacketed units. If you plan to install the unit in a plastic model, you want the jacketed type. Otherwise, it will melt/deform the shell and stack area of the boiler shell.5) Never let the unit run dry of smoke oil. The tiny heat element will be destroyed in a matter of seconds if allowed to go dry. As such, having an on/off switch is a must and you want to turn the unit off when you see the volume of smoke has diminished.6) The wire Seuthe uses on these smoke units is the most brittle type of solid core wire you will ever encounter. It will bend once, maybe twice. Beyond that snap and the unit is ruined. It is especially vulnerable right at the point that it exists the unit itself. Of course, it is impossible to make any repair to it at that point./end of quoteThere are many responses to googling resistor for sleuthe but they all seem to be very low 6 ohms and 0.6 watt. I would look at a wider spread of advice. Link to comment Share on other sites More sharing options...
The Mattle Posted January 26, 2015 Author Share Posted January 26, 2015 Thanks again guys !!! Link to comment Share on other sites More sharing options...
The Mattle Posted January 26, 2015 Author Share Posted January 26, 2015 Thanks again guys !!! Link to comment Share on other sites More sharing options...
PJR_slo Posted January 26, 2015 Share Posted January 26, 2015 HiSeuthe smoke units running on 12 - 16V draw about 125mA when working, but the startup current (when cold) is somewhere in the region of 300mA which reduces quickly as the coil heats up.This is a problem with even the Sapphire decoder which will cut out the function (with an overload error code) and will not reset until power is removed. There are 2 solutions:1. Use a 12V sub-miniature relay which are relatively inexpensive, but can be difficult to place within the loco2. Use a decoder which will run it directly - I use a Zimo which will also allow you to set the smoke output and therefore you don't have to resistor the unit. I don't like the idea of using 2 function outputs as you may still exceed the maximum and you need both outputs switching on at exactly the same time, or you risk burning out a basic decoder. Peter Link to comment Share on other sites More sharing options...
96RAF Posted January 26, 2015 Share Posted January 26, 2015 I hadn't thought about the ergonomics of switching 2 F-s on at once. Link to comment Share on other sites More sharing options...
poliss Posted January 26, 2015 Share Posted January 26, 2015 My advice comes from the worlds leading brand of decoders.http://www.tcsdcc.com/Customer_Content/Technical_Info/Tech_Info/FAQPage.php?q=5 Link to comment Share on other sites More sharing options...
Tee1707818014 Posted January 26, 2015 Share Posted January 26, 2015 Wired like this?/media/tinymce_upload/image49.jpg Link to comment Share on other sites More sharing options...
96RAF Posted January 26, 2015 Share Posted January 26, 2015 My advice comes from the worlds leading brand of decoders.http://www.tcsdcc.com/Customer_Content/Technical_Info/Tech_Info/FAQPage.php?q=5I was mind locked onto Hornby decoders where the R8249 does not support function mapping per TCS method of hanging both function outputs onto one F - button. Link to comment Share on other sites More sharing options...
The Mattle Posted January 26, 2015 Author Share Posted January 26, 2015 Thank you all once again for your advice. I shall firstly and see if a can fit a mini relay, if not I'll go the route of Zimo... Being new to this forum I've found you all very helpfull. Link to comment Share on other sites More sharing options...
shagey Posted April 2, 2015 Share Posted April 2, 2015 HiI am lookin' to the sameHave you got the smokeunit to work. I got the smokeunit to work but it killed the function on the decoder.An help you can give. I have looked on here so much about it.I have looked at bit about the relay but what relay do you need some say you need a resister some say you dont some say you need a diode some say you dont.Can you help Shane Link to comment Share on other sites More sharing options...
shagey Posted April 2, 2015 Share Posted April 2, 2015 HiI am lookin' to the sameHave you got the smokeunit to work. I got the smokeunit to work but it killed the function on the decoder.An help you can give. I have looked on here so much about it.I have looked at bit about the relay but what relay do you need some say you need a resister some say you dont some say you need a diode some say you dont.Can you help Shane Link to comment Share on other sites More sharing options...
Flashbang Posted April 3, 2015 Share Posted April 3, 2015 HiI would, opt for the relay control method. It saves the decoder from being overloaded on its function outputs.Diode... Optional, but its use is to remove the Bemf produced as the relay de energises. The Bemf generated could cause decoder failure, hence a simple diode across the relays coil which costs a few pence will stop this. - 1N4001 etc diode is fine.Resistor.. Optional and really dependent upon your DCC rail voltage and the maximum rated working voltage of the smoke unit being used. Older factory fitted smoke units may well be able to operate at a voltage above the nominal 12 volts. DCC rail voltage in OO is typically around 14 - 15 volts. Example of a micro 12v relay...http://www.rapidonline.com/electronic-components/a12-wk-12v-dpdt-micro-relay-60-4032 Link to comment Share on other sites More sharing options...
shagey Posted April 3, 2015 Share Posted April 3, 2015 Hi All AgainThe smoke units that I am trying to get to work are the old tri-ang/hornby ones with the element in them.Need all the help I can get.I have got a relay today from Maplin but it only has 6 connection legs but 12v 2A. Do you think it will be OKShane Link to comment Share on other sites More sharing options...
Chrissaf Posted April 3, 2015 Share Posted April 3, 2015 Shane,It would help to answer your question if you could state the Maplin Product Code for the item you have purchased. Link to comment Share on other sites More sharing options...
shagey Posted April 12, 2015 Share Posted April 12, 2015 HiI would, opt for the relay control method. It saves the decoder from being overloaded on its function outputs.Diode... Optional, but its use is to remove the Bemf produced as the relay de energises. The Bemf generated could cause decoder failure, hence a simple diode across the relays coil which costs a few pence will stop this. - 1N4001 etc diode is fine.Resistor.. Optional and really dependent upon your DCC rail voltage and the maximum rated working voltage of the smoke unit being used. Older factory fitted smoke units may well be able to operate at a voltage above the nominal 12 volts. DCC rail voltage in OO is typically around 14 - 15 volts. Example of a micro 12v relay...http://www.rapidonline.com/electronic-components/a12-wk-12v-dpdt-micro-relay-60-4032 HiDo you have a wireing diagram you could let me have I have just wired a relay up luck it has not done the decoder just the function Shane Link to comment Share on other sites More sharing options...
shagey Posted April 12, 2015 Share Posted April 12, 2015 Shane,It would help to answer your question if you could state the Maplin Product Code for the item you have purchased. Hi ChrisThe only numbers I have on the relay are LU-12 3A 120VAC 3A 24VDC I think it is made by RAYEXELECShane Link to comment Share on other sites More sharing options...
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