RMweb Premium Tim Dubya Posted April 19, 2015 RMweb Premium Share Posted April 19, 2015 I would like to use one of the (two) 16v AC outputs (@1 amp each) from my Gaugemaster M1 transformer to power 3 tortoise motors. I will be using the other output for a Gaugemaster WS controller for my shunting plank. I know very little about electronics but was wondering if it was as simple as using a 16v AC to 12v DC converter to utilise the spare 16v AC and thereby use the 12v DC to power the tortoise motors? I've had a look at several models (Maplin / All Components) but found these on Ebay for a couple of quid, would they be safe to use with a tortoise or three? 16v AC to 12v DC Converter Specs.pdf I appreciate I can just use the 16v AC with steering diodes (whatever they are???) to directly power the Tortoise but would like the advantage of having a 12v DC supply. I know I can buy cheap power supplies but these look a neater option and could be hidden in my control panel with less spaghetti hanging about. TIA Cheers Link to post Share on other sites More sharing options...
cliff park Posted April 19, 2015 Share Posted April 19, 2015 At its simplest all you need is four diodes, or a bridge rectifier, which is basically four diodes in a 'package'. You could add a smoothing capacitor to even things out a bit, all of which should really cost a few pennies. However the logistics of buying individual components from the likes of Maplin means it will cost you more. Nothing wrong with Maplin of course, it's dealing in small numbers that is the problem. I don't understand your cryptic location reference, 71G C.U.B.A ? Link to post Share on other sites More sharing options...
Rods_of_Revolution Posted April 19, 2015 Share Posted April 19, 2015 Those look as though they'll give you 16v DC from 16v AC in so you may need to put a resistor in the circuit if you want 12v, but other than that they should be fine. As I understand it, using the equation I x R = V, you'll need a 12ohm resistor, 1amp x 12ohms = 12 volts. The circuit will have already have some resistance in so a 12ohm resistor will probably reduce the current to a bit less than 12v but that'll just mean the motor throws slower and quieter. I'm sure someone better at electronics can confirm or correct me! All the best, Jack Link to post Share on other sites More sharing options...
Austrag Posted April 19, 2015 Share Posted April 19, 2015 Personally I wouldn't use them for that. It seems that there isn't a facility for a heat sink to be fitted if they overheat. This item is more suited. 16v-40v-to-12v-10A-120W-DC-DC-Waterproof-Shockproof-Power-Step-Up-Down-Converter on eBay. More expensive but will allow all your peripherals to be safely powered. Link to post Share on other sites More sharing options...
chaz Posted April 19, 2015 Share Posted April 19, 2015 Those look as though they'll give you 16v DC from 16v AC in so you may need to put a resistor in the circuit if you want 12v, but other than that they should be fine. As I understand it, using the equation I x R = V, you'll need a 12ohm resistor, 1amp x 12ohms = 12 volts. The circuit will have already have some resistance in so a 12ohm resistor will probably reduce the current to a bit less than 12v but that'll just mean the motor throws slower and quieter. I'm sure someone better at electronics can confirm or correct me! All the best, Jack Hmm. Current a bit less than 12V? You are a bit confused, 12V is the potential difference of the supply. Current (in amps or milliamps) is the result of applying that voltage to a circuit which will include resistance. As far as ohms law is concerned 12R is a very small resistance so you can't ignore the resistance of the Tortoise. Personally I would use a voltage regulator to get a stable 12V which would make the rest easy. Chaz Link to post Share on other sites More sharing options...
RMweb Premium Tim Dubya Posted April 19, 2015 Author RMweb Premium Share Posted April 19, 2015 Thanks for the replies, unfortunately I know very little nothing about electronics so would need a very basic description of the alternatives and if possible a circuit diagram for the resistor location? (I am from Radstock after all). I don't understand your cryptic location reference, 71G C.U.B.A ? County that Used to Be Avon Cheers Link to post Share on other sites More sharing options...
cromptonnut Posted April 19, 2015 Share Posted April 19, 2015 I've used for similar purposes one of these Kato devices, with two wires soldered to where the connectors to the Kato points are. http://www.osbornsmodels.com/kato-24-842-dc-converter-1-3218-p.asp Link to post Share on other sites More sharing options...
cliff park Posted April 19, 2015 Share Posted April 19, 2015 Austrag, your reference is for a DC to DC converter, what he needs is AC to DC, which is considerably easier and cheaper Link to post Share on other sites More sharing options...
RMweb Premium Tim Dubya Posted April 19, 2015 Author RMweb Premium Share Posted April 19, 2015 I've used for similar purposes one of these Kato devices, with two wires soldered to where the connectors to the Kato points are. http://www.osbornsmodels.com/kato-24-842-dc-converter-1-3218-p.asp Brilliant!, exactly what I'm after (and no need to understand the innards!). Just ordered this and so I can now remain totally ignorant to all things electronic (although I will attempt to learn more over time, honest!). Thanks to all for your help (and attempts to educate me). Cheers Link to post Share on other sites More sharing options...
cromptonnut Posted April 19, 2015 Share Posted April 19, 2015 These devices don't have a huge current capacity (as you'd need for Peco thump type motors) but for slow action ones like the Tortoise, they're ideal. I don't know how many you'd be able to run off of one of these devices though - don't have current capability/consumption information to hand. Link to post Share on other sites More sharing options...
Austrag Posted April 19, 2015 Share Posted April 19, 2015 Yes, my error but now corrected. Apologies all around. AC/DC 9V-48V to 1.8V-25V Adjustable Step Down Power Supply Module Converter Link to post Share on other sites More sharing options...
RailWest Posted April 19, 2015 Share Posted April 19, 2015 Going a bit OT..... The problem with "...Used to Be A***" <spit> is the number of organisations who still think that it exists :-( I refuse to deal with any local business who can't even get their own address correct. After all, if they don't even know what county they are in, how do I know they can do their sums correctly ? :-) That's my rant for the day! PS: I was in Radstock on Thursday - funny to think that it once had two railways and several tramways, you'd never know it now. So much for heritage..... Link to post Share on other sites More sharing options...
Grovenor Posted April 19, 2015 Share Posted April 19, 2015 The simplest solution is just to use the steering diode method as given in the tortoise instructions, works perfectly well and the wiring is simpler than using 12V DC. I don't understand why you think 12V Dc has an advantage in this application. Regards Keith Link to post Share on other sites More sharing options...
cromptonnut Posted April 19, 2015 Share Posted April 19, 2015 Am I right in thinking that a 'steering diode matrix' is what you and I would call a bridge rectifier? Link to post Share on other sites More sharing options...
chaz Posted April 20, 2015 Share Posted April 20, 2015 Am I right in thinking that a 'steering diode matrix' is what you and I would call a bridge rectifier? Not quite. A bridge rectifier has four diodes and turns AC into (very lumpy) DC. As a Tortoise has a stall motor all that is required is to reverse the polarity of the supply to cause it to throw (or throw back). This can be done easily with DC by wiring a DPDT switch as a polarity changer. When using AC two diodes facing opposite ways connected to a SPDT does the trick. I would still consider a proper DC supply, which can be done cheaply by adding a recifier, voltage regulator and a couple of capacitors to an AC output as the best way to go - but I quite understand how someone with no experience of electronics might find this tricky. Chaz Link to post Share on other sites More sharing options...
RMweb Premium Tim Dubya Posted April 20, 2015 Author RMweb Premium Share Posted April 20, 2015 I say C.U.B.A. but always use Somerset in my postal address! ('cos that's where I live). PS: I was in Radstock on Thursday - funny to think that it once had two railways and several tramways, you'd never know it now. So much for heritage.....Interesting to note that the "new" road layout is in fact going back to the original road layout pre GWR Bristol - Frome Branch! Still, they have a nice new big roundabout to use how they wish (the Highway Code does not apply in Radstock!). The simplest solution is just to use the steering diode method as given in the tortoise instructions, works perfectly well and the wiring is simpler than using 12V DC. I don't understand why you think 12V Dc has an advantage in this application. Regards Keith Thing is (and as I explained earlier), I don't understand what these things are, where to get them or how exactly to wire them! DC = one wire terminal 1 other wire terminal 8 - easy! (I've wired several tortoises using this method with 100% success rate). I have used an old transformer (Duette) in the past for PM's but for this layout I want a neat small control panel with just one (small) transformer (Gaugemaster M1). It would be an advantage to have a DC supply without the hassle of an extra transformer / power supply, so I could also use it to power the LED's for the control panel lights. Anyway, I've been given the solution (which I understand with my extremely limited knowledge of electronics) that should do the job and I'll give feedback as to whether it can drive the 3 PM's and LED's I need it to. Thanks to all for answering my questions. Cheers Link to post Share on other sites More sharing options...
chaz Posted April 20, 2015 Share Posted April 20, 2015 I say C.U.B.A. but always use Somerset in my postal address! ('cos that's where I live). Interesting to note that the "new" road layout is in fact going back to the original road layout pre GWR Bristol - Frome Branch! Still, they have a nice new big roundabout to use how they wish (the Highway Code does not apply in Radstock!). Thing is (and as I explained earlier), I don't understand what these things are, where to get them or how exactly to wire them! DC = one wire terminal 1 other wire terminal 8 - easy! (I've wired several tortoises using this method with 100% success rate). I have used an old transformer (Duette) in the past for PM's but for this layout I want a neat small control panel with just one (small) transformer (Gaugemaster M1). It would be an advantage to have a DC supply without the hassle of an extra transformer / power supply, so I could also use it to power the LED's for the control panel lights. Anyway, I have ordered the solution that suits me and will give feedback as to whether it can drive the 3 PM's and LED's I need it to. Thanks to all for answering my questions. Cheers It might be worth doing an audit of your current needs. Each Tortoise is going to consume about 36mA. The consumption of your LEDs will depend on the resistor you fit as protection but 20mA is a reasonable estimate. When I did a similar exercise for Dock Green I was surprised at what the total came to. Nine Tortoises and a couple of dozen LEDs soon mounts up. I bought two of those plug-type PSUs - a 12V 1A for the Tortoises and a 5V 5A for the LEDs (I think the latter is intended for use with a type of video camera). Shop around on the net - cheap as chips and a very simple solution to your problem. Chaz Link to post Share on other sites More sharing options...
RMweb Premium Tim Dubya Posted April 26, 2015 Author RMweb Premium Share Posted April 26, 2015 Thing is (and as I explained earlier), I don't understand what these things are, where to get them or how exactly to wire them! All explained by Mr Lambert on his useful (as always) website. The AC - DC converter has arrived but I've also ordered some diodes and some SPDT switches if plan A fails (or I may just use it for LED's). Must crack on and get the layout built first though. Cheers Link to post Share on other sites More sharing options...
Butler Henderson Posted April 26, 2015 Share Posted April 26, 2015 See Figure 1 of the Lenz LS150 manual on how to wire up a motorised switch machine like a Tortoise www.lenzusa.com/1newsite1/Manuals/LS150.pdf Replace the + C and - terminals with the left, common., and right connections on your point motor switch Link to post Share on other sites More sharing options...
Suzie Posted April 26, 2015 Share Posted April 26, 2015 Using stall motors and end cut off motors with AC is much easier than with DC. As you can see from this diagram all you need is two diodes and the SPST switches on your control panel, and a single wire (the green one) to each tortoise. If using Tortoise motors specifically (not Cobalt or end cutoff motors) you can put a pair of inverse parallel LEDs in the green wire and you have a mimic diagram showing the route too! (one LED lights for the main route, the other for the diverging route) It is a lot simpler than most people think to do this. Link to post Share on other sites More sharing options...
chaz Posted April 27, 2015 Share Posted April 27, 2015 Using stall motors and end cut off motors with AC is much easier than with DC. As you can see from this diagram all you need is two diodes and the SPST switches on your control panel, and a single wire (the green one) to each tortoise. Tortoise wiring.png If using Tortoise motors specifically (not Cobalt or end cutoff motors) you can put a pair of inverse parallel LEDs in the green wire and you have a mimic diagram showing the route too! (one LED lights for the main route, the other for the diverging route) Tortoise mimic wiring.png It is a lot simpler than most people think to do this. Does the Tortoise motor offer enough resistance to limit the current through the LEDs, or is a resistor still required? Link to post Share on other sites More sharing options...
Suzie Posted April 27, 2015 Share Posted April 27, 2015 I measured the current through a tortoise when stalled at 6mA on 12V so there should be no need for a resistor. Link to post Share on other sites More sharing options...
Crosland Posted April 27, 2015 Share Posted April 27, 2015 Wiring LEDs in series with the motor is explicitly shown in the tortoise instructions. They need to be bare LEDs, not the "12V LED" type that include a resistor. Just to avoid doubt, you DO need resistors if using the auxilliary contacts for switching LEDs, unless you use 12V LEDs. Link to post Share on other sites More sharing options...
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