bertiedog Posted July 26, 2011 Share Posted July 26, 2011 Just had a chat about the Lenz system with a friend who works in electronics full time,and he has a Lenz system. The signal getting through is done on a HF capacitive method, but does not maintain or even try to maintain full contact, it is designed to respond to nearly 80% of the DCC signal corrupted or missing. When the signal is missing it defaults to the last received signal,but instantly gets control back on resumption of the weak signal.or re-connection with the track. The power control just needs very occasional refresh as the power decays away, the reverse needs about 20 % of the normal signal, and the circuit contains an error correction system to over come glitches. The power is stored in the power capacitor, and the circuit can maintain about 200ma for about 2 to 3 seconds, longer with a lower drain, and is far shorter if a heavier load is involved. It feeds a switched power supply circuit to raise the capacitors voltage to the motor level, but versions for larger locos now have higher voltage capacitors that do not need the converter. This covers about the basic background to them. I will try the DC circuit as long as I can find a polarised latching relay that will match the circuit, if it is out of the range it will reverse in a very strange manner, going forward slowly, then reversing, but juggling the values should get round this.. However I don't think it will fit the smaller locos that Kenton specified..... Stephen. Link to post Share on other sites More sharing options...
bertiedog Posted July 26, 2011 Share Posted July 26, 2011 Going back to the simplest way, there are indeed now made 12 volt 2 farad power caps that could just be connected "across" the motor,(not quite that simple) but would need thoughts about reverse running, diode protection? or a regulator circuit,or duel capacitors? They are still small,,about 6mm thick by 15m diameter,, and using them eliminates the battery. Stephen. Link to post Share on other sites More sharing options...
Kenton Posted July 27, 2011 Author Share Posted July 27, 2011 However I don't think it will fit the smaller locos that Kenton specified..... I was thinking along the lines of a battery suspended under the chassis, in many kit 0-4-0 there would be some space between or even under the frames. How to miniaturize the circuit is a whole new discussion. I doubt in early days DCC chips were very small and from what I've seen they continue to be reduced in size. We have come a long way since the OP to a component set that might at least work. Link to post Share on other sites More sharing options...
goodmayes Posted October 22, 2012 Share Posted October 22, 2012 Power reversal is simply covered by my circuit. The first thing the power hits is the coil of a latching relay, which controls the polarity of power fed to the motor. Reversal of the polarity on the track will throw the relay, the power to the motor is then reversed to match the track polarity. Andi I thought about this a little over the weekend, and am not convinced about the simplicity of operation of the reversing relay. The DC motor will run, at intentional different speeds, over a voltage range of around 3v to 15 v. It seems to me that the reversing relay must pull in well below the 3v minimum motor speed, or the loco will be either ignoring, or later doing, unexpected reversing commands, while the operator is attempting to do slower shunting moves. And if the relay coil operates at low voltage, it will have a relatively low impedance, and need further protection against the higher track voltages. Ted Link to post Share on other sites More sharing options...
Suzie Posted October 22, 2012 Share Posted October 22, 2012 Latching relays are quite straightforward to understand. They have a set of contacts and a magnet that will hold the contacts closed, but the magnet is not strong enough to pull the contacts in. Applying a current to the coil to create a magnetic field the same as the magnet will close the contacts, and the magnet will keep them closed when current is removed. If a reverse current is applied it will negate the effect of the magnet and the contacts will disengage by the action of a spring. Because the magnet is only weak the contacts will remain open. Most latching relays have a second coil wound the opposite way to the first so that energising the second coil can be done instead of having to reverse the current in the first coil. Not just me who is blind to the word 'Latching' Link to post Share on other sites More sharing options...
Blacque Jacque Posted October 22, 2012 Share Posted October 22, 2012 A simple zener regulator will protect the relay coil from overvoltage at the expense of a little current draw. Link to post Share on other sites More sharing options...
goodmayes Posted October 23, 2012 Share Posted October 23, 2012 I thought about this a little over the weekend, and am not convinced about the simplicity of operation of the reversing relay. The DC motor will run, at intentional different speeds, over a voltage range of around 3v to 15 v. It seems to me that the reversing relay must pull in well below the 3v minimum motor speed, or the loco will be either ignoring, or later doing, unexpected reversing commands, while the operator is attempting to do slower shunting moves. And if the relay coil operates at low voltage, it will have a relatively low impedance, and need further protection against the higher track voltages. Ted Ooops, Terribly sorry, I seem to have somehow posted to the wrong thread. I thought I was commenting on the keep-alive DC one. Red faced Ted Link to post Share on other sites More sharing options...
RMweb Premium kevinlms Posted October 23, 2012 RMweb Premium Share Posted October 23, 2012 I was thinking along the lines of a battery suspended under the chassis, in many kit 0-4-0 there would be some space between or even under the frames. How to miniaturize the circuit is a whole new discussion. I doubt in early days DCC chips were very small and from what I've seen they continue to be reduced in size. We have come a long way since the OP to a component set that might at least work. Since this thread has been re-opened - has anyone got Andi's circuit to work usefully? Or something else? Link to post Share on other sites More sharing options...
28XX Posted October 24, 2012 Share Posted October 24, 2012 To turn this discussion on its head, why not use radio control and run the locomotive off the battery most of the time. Plain track sections could be energised to charge the batteries, leave the switches and crossings dead. A quick look on the net shows receivers barely larger or dearer than a DCC chip which are able to drive a brushed motor directly. Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted November 22, 2012 RMweb Gold Share Posted November 22, 2012 Since this thread has been re-opened - has anyone got Andi's circuit to work usefully? Or something else? I've built it myself, not with the latching relay yet but the electronic part of it and yes it does seem to work. Andi Link to post Share on other sites More sharing options...
ZippyHG Posted November 22, 2012 Share Posted November 22, 2012 I too also built it, without the relay, and yes it does work. Did have a go at converting it to DCC but just made things smoke a bit !!! Link to post Share on other sites More sharing options...
RMweb Gold Dagworth Posted November 26, 2012 RMweb Gold Share Posted November 26, 2012 http://www.rmweb.co.uk/community/index.php?/topic/63055-capacitor-assistance/page__st__75&do=findComment&comment=857531 Andi Link to post Share on other sites More sharing options...
28XX Posted December 11, 2012 Share Posted December 11, 2012 Here's a company doing R/C trains. http://www.antenna-models.com/#Comparison Not a customer - yet. Link to post Share on other sites More sharing options...
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