noiseboy72 Posted March 21, 2012 Share Posted March 21, 2012 A 1/4W resistor should be fine, as the current pulse will be fairly brief. On my stay alive circuit using 5V supercaps, a half watt or larger is required as it is part of the voltage dropper feeding into the Zener diode. Even 2 1/2 Watt 200 Ohm resistors get a little warm! Link to post Share on other sites More sharing options...
dave flint Posted March 22, 2012 Share Posted March 22, 2012 Cheeky I know, but any chance of sharing your design with us - PM me if you wish. Or just tell me to clear off ! Link to post Share on other sites More sharing options...
noiseboy72 Posted March 23, 2012 Share Posted March 23, 2012 Cheeky I know, but any chance of sharing your design with us - PM me if you wish. Or just tell me to clear off ! Have a look on Page 2 of this thread. The circuit and some notes is all there! I have been running it for a few weeks now and all is still good with it. Link to post Share on other sites More sharing options...
dave flint Posted March 23, 2012 Share Posted March 23, 2012 Ah, yes. Thank you ! I.note you didn't connect it to the two wires for a stay alive, rather soldered onto the chips bridge rectifier. Think that puts it beyond my skills, but very pleased that you're stir happy with it after using it for a while. Have to say I'm pleased with the use of the bigger caps with the dcc concepts chips. I may invest in some tcs kit for the really small locos, as the use of big caps is difficult thanks to space issues. Link to post Share on other sites More sharing options...
Marty Mc Posted March 27, 2012 Share Posted March 27, 2012 Hi Can I add some info here to clear up some mis-understandings. DCC Concepts Stay alive was designed with 2 key elements in mind smoothing running at low speeds (less cogging of motor) and a momentary kick to the motor on loss of power. Guys it is not a magic bullet you still need to clean your tracks and wheels. BromsMods, on 15 March 2012 - 00:37 , said: It won't work, I'm told by TCS, as there is additional software installed which needs to match up. The DCC Concepts stay alive will work with TCS decoders, though. Yep, John is correct on this. Connected up the KA1 to the DCC Concepts decoder and while it worked ok while power was supplied to the track, the motor took off like a rocket as soon as power was removed (for a second or two). With the TCS/KA1 power can be removed (for a second or so) and reapplied with negligible effect on the speed of the motor. Ok easily fixed just change CV 29 and switch DC off and thats the special software TCS are using...... a standard feature on just about every decoder. Martin Link to post Share on other sites More sharing options...
dave flint Posted March 29, 2012 Share Posted March 29, 2012 So youre saying the tcs stay alive works with a dcc supplies chip if dc is off ? ll, Can anyone vouch for this ? Dcc concepts decoders should have dc off anyway for their own stay alive to work properly. Link to post Share on other sites More sharing options...
tender Posted March 29, 2012 Share Posted March 29, 2012 So youre saying the tcs stay alive works with a dcc supplies chip if dc is off ? ll, Can anyone vouch for this ? Dcc concepts decoders should have dc off anyway for their own stay alive to work properly. Well, having tried it, I can honestly say, John (BromsMods) is right, it doesn't work (for me) with the DCC Concepts decoder, (DC on or off). In any case, having used it with the TCS decoder I cant see any advantage in trying to use it with the DCC Concepts decoder. Their both about the same price and the TSC direct plug (8pin) is significantly smaller. Link to post Share on other sites More sharing options...
Nigelcliffe Posted August 7, 2012 Share Posted August 7, 2012 An update to this thread. I've just installed a TCS KA2 unit in a 7mm scale Simplex (otherwise known as "the shed on wheels"). This is a small 0-4-0, with a Mashima motor. Decoder is a Zimo MX63. The KA2 is installed between decoder positive (blue) and decoder ground (also called "mass" on some Zimo diagrams). Attaching to the ground requires soldering a wire to the decoder, though there are pads for this around the edge of Zimo decoders. With the KA2 in place and the loco running at a middle speed, I disconnected the track power. The loco ran on for about a yard, taking about 20 seconds before stopping, towards the end of the run, the speed was dropping a lot, but the main part of the run was at a good speed. That's at least ten times what is needed for any "bad pickup" situations. Reading and writing of CV values is fine with the KA2 in place. The KA2 keeps power to the decoder until it is fully discharged, so the loco will "remember" its last speed when track power is re-applied. This can have some negative consequences if a loco goes back on the track after many minutes off the track and then carries on running at its old speed. The solution is to fit a resistor between the two wires to the KA2 to discharge the capacitors, I've used 1k-ohm, which takes a few minutes to discharge the capacitors. I'm going to try the KA2 on a Zimo sound chip, though expect similar performance. I did remove the shrink wrap from the KA2 to see what was inside. Nothing too surprising; 6 capacitors, each 1F 2.7v in series, giving a total of 0.16F at 16v. A couple of diodes for charge-discharge current paths, a 150 ohm resistor for charging the capacitors (without it, the capacitors would draw too much charging current, and probably be seen as an over-load on the command station and shut everything down). a component which looks like an inductor, probably there so the KA2 works with RailCom. Those components are very similar to the DIY circuits suggested in the Zimo manual, though lacking a discharge resistor (which I mentioned above) and the position of the inductor is different (and may be required for loading sound or changing firmware on Zimo decoders). The performance of 0.16F of capacitors is about what I'd expect from experience using electrolytic capacitors with of about 0.001 to 0.005F (1000uF to 5000uF). I hope this helps other experimenters. - Nigel Link to post Share on other sites More sharing options...
autocoach Posted August 8, 2012 Share Posted August 8, 2012 NCE has also announced integrated keep-alive decoders. Will have to see when they are available. Link to post Share on other sites More sharing options...
autocoach Posted November 18, 2012 Share Posted November 18, 2012 I am resurrecting this topic. Has anyone made any advances with Keep Alive technology. I have a Dapol/Kernow Beattie Well that is starting to stall on well cleaned and contact checked electrofrog turnouts where it did not before. A second BWT does not stall as much but is starting to show some performance deterioration. I suspect something worn/awry in the internal contacts but am loath to open up the mechanism so a keep alive may be a better solution. Anyway, I have been thinking if anyone has any experience fitting tiny Keep Alive decoders to the BWT or similar engines? (I am not specifying a brand here, but TCS is most readily available to me.) Has anyone any experience with such small spaces or perhaps putting a Keep Alive in an N scale steam engine. I don't really want to trail a permanently coupled van behind the locomotive. Link to post Share on other sites More sharing options...
Nigelcliffe Posted November 19, 2012 Share Posted November 19, 2012 Try Tantalum "brick" capacitors. They are available in 16v rated 220uF. That might have a positive effect, but its for fractions of a second. They can be fitted in parallel to increase capacitance. The devices are for surface mounting, though with only two terminals they should be easy to fit onto a thin bit of PCB. - Nigel Link to post Share on other sites More sharing options...
Butler Henderson Posted November 19, 2012 Share Posted November 19, 2012 I would suggest a 16v capacitor is a bit risky particularly when some dcc systems exceed that voltage and you would not want to be near a tantalum that explodes. Link to post Share on other sites More sharing options...
deadlyduck Posted March 6, 2015 Share Posted March 6, 2015 Ive put some super caps onto a Zimo MX634d,do i need to put something across them to release the power when taken off the track.If so could you point me the right direction.Thank you Link to post Share on other sites More sharing options...
Simond Posted March 13, 2015 Share Posted March 13, 2015 Have a look at my PD thread. http://www.rmweb.co.uk/community/index.php?/topic/79052-porth-dinllaen-in-0/?p=1590807 HTH Simon Link to post Share on other sites More sharing options...
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