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Keep Alive/ Stay Alive decoders





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#26 Oldddudders

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Posted 06 March 2012 - 15:24

I think the clue to the significant difference in the performance of the Lenz & DCC Concepts products is probably in the price. The Oz product adds a little value for not very much wonga - the Lenz does the "party tricks" and costs accordingly. Each has its attractions, but they are not truly comparable.

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#27 tender

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Posted 06 March 2012 - 17:47

The stay alive on DCCconcepts decoders is only good for aprox 2 seconds but that is uaually enough to get loco over a small dirty spot. It also helps slow running.

Cheers

Ian


I'd like to know if anybody gets this out of a DCC concepts decoder (2 seconds), mine stops as soon as all wheels are on the tape. At best I would think it's in the order of milliseconds if that. Unless my stay alive has died!!!

Ray
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#28 Butler Henderson

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Posted 06 March 2012 - 17:52

The DCC concepts modules use a 470uF capacitor, at http://members.optus...north/alive.htm it is recommended that the capacitor is at least 2200uF. Incidentally anyone wanting any 1N400x diodes may find a trip to their nearest Maplin worthwhile as they have a pack of 50 on sale at 20p (order code N47GK) !!!

#29 dave flint

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Posted 06 March 2012 - 21:41

Whilst initially pleased with my DCC Concept chips and their stay alives, a couple of the stay alives now seem to have failed. I would also liked them to have offered larger capacitors. Correspondence with someone involved with DCC Concepts highlighted a reluctance to do so, partly from the physical size of the things, but also a bit of a self righteous attitude, in that you really shouldn't need them in the first place.


And I'm sad to see that a snobbish mindset has surfaced on this thread too. That's fine - yes, we shouldn't need to use them in a perfect world, but with lots of 0-6-0 and 0-4-0 locos, setrack (so insulfrog) points and a roundy roundy thing for my small son to use for his Thomas loco;s lurking in the garage, I need all the help I can get.

I attempted to use a bigger 4700 capacitor with a DCC Concepts chip, and was told I should still use the small circuit board on the top of one of their stay alives. Well, I prized it off gently, but it didn't work. Can anyone suggest a possible circuit to add between the DCC concepts black and blue wires and a big capacitor ? I've added extra "official" stay alives (in parallel) without much apparent improvement as well.

Or does the TCS decoder range offer an easier path to DIY stay alive manufacture and installation ?

Electronics aren't my strong point, and I had a look at the above link but couldn't see anything relevant. Any help much appreciated.

Edited by dave flint, 06 March 2012 - 21:46 .


#30 tender

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Posted 06 March 2012 - 22:57

Whilst initially pleased with my DCC Concept chips and their stay alives, a couple of the stay alives now seem to have failed.


Hi Dave.
What makes you think the stay alive capacitor has failed? I must admit I was disappointed with the performance of these decoders offering very little (if any) improvement over a normal decoder i.e. doing the tape test, it gets no further than an ordinary decoder. I'm now beginning to wonder if my stay alive's are dead as well.

#31 Butler Henderson

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Posted 06 March 2012 - 23:08

See the circuit on the web page http://members.optus...north/alive.htm as discussed earlier in this thread. 4700uF capacitors are pretty big.

#32 melmerby

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Posted 06 March 2012 - 23:38

See the circuit on the web page http://members.optus...north/alive.htm as discussed earlier in this thread. 4700uF capacitors are pretty big.

Remember the "super" caps used for clock back up etc. on computers?. If you could get near their capacitance/volume ratio the 4700uF caps wouldn't be very big at all!

Keith

#33 tender

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Posted 07 March 2012 - 00:29

Remember the "super" caps used for clock back up etc. on computers?. If you could get near their capacitance/volume ratio the 4700uF caps wouldn't be very big at all!

Keith


Also remember that the majority of these are only rated at 5.5volts (Bang). The TCS KA1 package looks like it's made up of 4 capacitors, maybe connected in series to get the higher working voltage.

#34 Suzie

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Posted 07 March 2012 - 03:39

You really have to look at what the solutions offer. The Lenz gold is the Rolls Royce of stay alive and they demonstrate it on the 12" of tape because they can, not because you are likely to need it in the real world.

There are four things that come to play in the Lenz Gold solution:-

1. Use of very high performance capacitors to reduce the size.

2. Use of low voltage capacitors to unsure maximum charge can be achieved.

3. A DC-DC converter to get all the power out of the capacitor.

4. Comparator input circuit to amplify a miniscule DCC signal to something readable.

The amount of increase in performance of all of this is huge, (1) gives you a 200%-300% improvement, (2) gives you a 75% improvement, (3) gives another 300%-400%, and (4) allows you to drive the train. Take all of this in to account and the Lenz solution is equivalent to having a capacitor twenty five times the size of the simple solution used by the other manufacturers.

The most that the average loco is likely to encounter is a dead frog, not a whole foot of tape, so you probably don't need the Lenz solution unless you are very tight for space or are doing some seriously slow running over dead frogs.

I have fitted a 4700uF 35V standard electrolytic to a DIY decoder (which has comparator input) that you can make for £5 (including the capacitor) and that will enable a Lima diesel with four wheel pickup to run on dirty track at speed step 1 all day. The Lenz solution at £80 is better, much better, when it comes to doing tricks, I have tried it myself in a Lima diesel for comparison, but you need to decide what you really need. The simple solution will probably not let you run a live frog point set the wrong way, but the Lenz will (I have tried it).

Comparator input will be present in any decoder that supports asymmetric braking, so those are the best decoders to add stay alive capacitors to. Adding them to more basic decoders is likely to just result in runaways or general uncontrollability.
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#35 tender

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Posted 07 March 2012 - 14:47

Thanks for that very concise explanation of the Lenz solution.
I think i'll give up on the DCC concepts stay alive as they seem to offer very little over a standard decoder. I might give the new TSC KA1 keep alive a try to see if that improves things. (TCS claim 3-6 seconds)
The only Loco i'm having a problem with is the Model Rail Sentinel (4 wheel pickup), and even then is only very occasionally.

Edited by tender, 07 March 2012 - 14:48 .


#36 melmerby

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Posted 07 March 2012 - 15:10

Also remember that the majority of these are only rated at 5.5volts (Bang). The TCS KA1 package looks like it's made up of 4 capacitors, maybe connected in series to get the higher working voltage.

You can get "super" caps up to 18v rating with capacities in tenths of a farad.

Keith

#37 Nigelcliffe

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Posted 07 March 2012 - 16:44

You can get "super" caps up to 18v rating with capacities in tenths of a farad.

Keith


Could you point to a supplier in UK please...

#38 tender

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Posted 07 March 2012 - 16:55

Could you point to a supplier in UK please...


The only one's I've seen with a rating greater that 5.5volts are bigger than the engine that I'm trying to fit one in.
I'd also be interested to see what Keith comes up with. In the meantime I've ordered a TCS KA1 to try out.

#39 melmerby

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Posted 07 March 2012 - 20:27

Could you point to a supplier in UK please...

http://uk.farnell.com/avx/bz12ga124zab/capacitor-super-0-12f-16v-0-16ohm/dp/1841705

Sorry, it's actually 16v 0.12F (memory let me down) but lots of capacity for it's size of 48mmx30mm,
Price is a problem - £97 plus vat!!!!

If you select a lower cap & voltage and use them in series? maybe they could be made to fit.
You should be able to get small capacitors in the 10000uF range these days

I was pointing out that super high caps can be quite small these days.
I remember in college days the lecturer saying you can't get caps in farads - they would fill this room!

Keith

#40 Ron Ron Ron

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Posted 07 March 2012 - 21:09

The only one's I've seen with a rating greater that 5.5volts are bigger than the engine that I'm trying to fit one in.

Sorry, it's actually 16v 0.12F (memory let me down) but lots of capacity for it's size of 48mm x 30mm,
Price is a problem - £97 plus vat!!!!


I don't know if it's of any use, but for comparison the TCS stay alive modules are...

KA1 (3-6 seconds) = 16.43mm x 26.72mm x 7.44mm ........... m.r.p. approx. £17.75 (in the USA)

KA2 (13-40 seconds) = 32.92mm x 11.63mm x 8.81mm .......... m.r.p. approx. £17.15 (in the USA)

Add $5 to the prices for the version fitted with a connector.
Actual retail prices will probably be lower.


.

#41 Oldddudders

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Posted 07 March 2012 - 21:16

I don't know if it's of any use, but for comparison the TCS stay alive modules are...

KA1 (3-6 seconds) = 16.43mm x 26.72mm x 7.44mm ........... m.r.p. approx. £17.75 (in the USA)

KA2 (13-40 seconds) = 32.92mm x 11.63mm x 8.81mm .......... m.r.p. approx. £17.15 (in the USA)

But not until June. Their claims are a little more modest as here http://www.tcsdcc.co.../Keep-Alive.php

#42 tender

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Posted 07 March 2012 - 21:51

But not until June.

Not sure what you mean by that, ordered one today (KA1) from Bromsgrove Models, in stock @£17.75 (I think).

Sorry, it's actually 16v 0.12F (memory let me down) but lots of capacity for it's size of 48mmx30mm,
Price is a problem - £97 plus vat!!!!

Yep, that's about the size of a Sentinel (well, not quite, but not far off), and more expensive than the Loco too.

#43 Ron Ron Ron

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Posted 07 March 2012 - 22:17

But not until June.


Ian, that's for the integrated KAT series decoders, with Stay Alive built-in.

The separate Stay Alive modules and matching decoders are already being made available AFAIK.


Their claims are a little more modest as here http://www.tcsdcc.co.../Keep-Alive.php


That's interesting, because it contradicts the figures given in all other parts of the TCS web site and in the user manuals !!!!!!




.

Edited by Ron Ron Ron, 07 March 2012 - 22:25 .

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#44 noiseboy72

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Posted 07 March 2012 - 22:19

I have just bought the parts to make a DC converter stay alive unit. I have bought a 5V - 9V converter, a couple of 1F caps, zener diodes and resistors (I already had the straight diodes) Cost: Less than £10.

If I get it all to work tomorrow as I plan, I will post the circuit diagram.
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#45 noiseboy72

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Posted 08 March 2012 - 11:29

Well, that was a morning well spent!
The DIY stay alive works quite well. About 1-2 seconds of power I would estimate. Better than a straight electrolytic, but not up to the standards of a Lenz unit. The circuit diagram and parts list is below. It cost less than £10 for the DC-DC converter and 1F capacitor from CPC, with all other components pennies when bought by the dozen.

I would be interested in peoples thoughts to improve the design and if anyone else builds one and trys it out. I have fitted mine to a mini decoder mounted on one of my R Stock cars. I lifted the plus end of the 2 diodes that make up the positive side of the bridge rectifier and soldered the input wire here. The GND went to the other terminal of the bridge rectifer. The feed into the decoder is via the blue function wire (Positive common return). This was all a little fiddly, but quite acheivable.

The resistors get quite warm on my Lenz Compact with the standard 16V transformer, so it is worth checking this value if your DCC system has a higher output.

The train is noticeably smoother and nicer to drive. Running over an insulated diamond crossing, even with one set of pick ups disconnected at minimum speed was fine, whereas before this would have led to stuttering, stalling and swearing! This decoder is set to restart at the bottom of the speed curve whenever power is lost, so the effect is most noticable. For the next build, I will go for the 12V output variant, as I feel this might give a little more run time.

Apologies for the scrappy install, I will neaten this up for the next build and squeeze it in a little tighter!

Well, that was a morning well spent!
The DIY stay alive works quite well. About 1-2 seconds of power I would estimate. Better than a straight electrolytic, but not up to the standards of a Lenz unit. The circuit diagram and parts list is below. It cost less than £10 for the DC-DC converter and 1F capacitor from CPC, with all other components pennies when bought by the dozen.

I would be interested in peoples thoughts to improve the design and if anyone else builds one and trys it out. I have fitted mine to a mini decoder mounted on one of my R Stock cars. I lifted the plus end of the 2 diodes that make up the positive side of the bridge rectifier and soldered the input wire here. The GND went to the other terminal of the bridge rectifer. The feed into the decoder is via the blue function wire (Positive common return). This was all a little fiddly, but quite acheivable.

The resistors get quite warm on my Lenz Compact with the standard 16V transformer, so it is worth checking this value if your DCC system has a higher output.

The train is noticeably smoother and nicer to drive. Running over an insulated diamond crossing, even with one set of pick ups disconnected at minimum speed was fine, whereas before this would have led to stuttering, stalling and swearing! This decoder is set to restart at the bottom of the speed curve whenever power is lost, so the effect is most noticable. For the next build, I will go for the 12V output variant, as I feel this might give a little more run time.

Apologies for the scrappy install, I will neaten this up for the next build and squeeze it in a little tighter!

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  • Stay Alive.jpg


#46 RedgateModels

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Posted 08 March 2012 - 12:48

hmmmm

looks interesting, with a bit of tidying you could end up with a package that is smaller than a 4700uF 16V electrolytic. Just one question, with a simple capacitor set-up you only need to find the neg of the bridge then connect the positive side of the cap (via resistor/bypass diode) to the blue wire. Simple enough to identify the positive of the bridge, but can your circuit be modded to work off two wires?

#47 noiseboy72

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Posted 08 March 2012 - 15:27

hmmmm

looks interesting, with a bit of tidying you could end up with a package that is smaller than a 4700uF 16V electrolytic. Just one question, with a simple capacitor set-up you only need to find the neg of the bridge then connect the positive side of the cap (via resistor/bypass diode) to the blue wire. Simple enough to identify the positive of the bridge, but can your circuit be modded to work off two wires?


Good question.
My thought is yes, by increasing the resistor value and omitting the diode between the input and output and also the reverse protection diode before it. My concern was that the discharge rate would be too high, as the voltage converter would feed back and try and to charge itself up! By increasing the resistor value, the impedance of the decoder should be much lower and that should take all the current. The reverse protection diode also drops the voltage slightly, so that the difference between the track supply and back up is a little less. I have found this is not really required, but as I am a fully paid up member of the Ham Fisted Society have left it in while I play with the circuit.

Might give it a go!

In terms of packaging, I was thinking of a shorter board, with a 1F cap at one end and the converter at the other. It would need a bit of airspace around the resistors but the rest of the components can be wedged in. I have some smaller diodes as well somewhere. The converter is good for 200mA, so enough for most motors that are already running.

#48 dave flint

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Posted 08 March 2012 - 18:23

Hi Dave.
What makes you think the stay alive capacitor has failed? I must admit I was disappointed with the performance of these decoders offering very little (if any) improvement over a normal decoder i.e. doing the tape test, it gets no further than an ordinary decoder. I'm now beginning to wonder if my stay alive's are dead as well.


I think they've failed as when lifted off the track (ie power removed) the wheels stop immediately. The other models so fitted still give their wheels a fraction of turn when lifted off - as these "duff" locos did initially.

I've checked wiring and all seems ok, but not helped by using heatshrink which doesn't allow you to easily open up past installations. Of course, they're all hard wired as well, and in models that were very awkward to take apart. So far three locos are affected.

I've also bought extra stay alive modules and wired them in parallel (as instructed) with no real discernable improvement in running. So, I am a little disappointed with them. Oh, and I had a coupld of decoders die under testing, as detailed in the thread on these decoders - and despite an offer of a replacement, non has so far been forthcoming. I suspect that I fell for a bit of "salesmans puff" on these chips, and the chap seems top have gone a bit quiet on here too.

I want a halfway house. I don;t need the Lenz's capabilities, but I need more than a DCC Concepts stay alive offers. I like the TCS chips but that's mopre money to fork out that I can't afford.

My soldering skills aren't up to soldering onto decoders, but I can make a little device from components. I don't see anything relevamt on the website mentioned previously, but can anyone suggest a possible DIY way to make a stay alive that goes to the black and blue wires of a dcc concepts decoder ?

Edited by dave flint, 08 March 2012 - 18:24 .


#49 Butler Henderson

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Posted 08 March 2012 - 19:20

Have you checked the voltage of your dcc system (ie take a reading between the blue and white wires of a loco fitted decoder) - DCC Concepts are using 16v caps so the cap could have failed if the voltage is higher (Multimaus users with a Roco supply beware unless you have dropped the voltage).

#50 tender

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Posted 08 March 2012 - 20:10

can anyone suggest a possible DIY way to make a stay alive that goes to the black and blue wires of a dcc concepts decoder ?


I must say I'm also disappointed with the 'stay alive' on the DCC concepts decoder. I've ordered one of the TSC decoders with the KA1 stay alive to try out. At least TSC make some claim as to the effectiveness of the device (2-6 seconds) so should be easy to see if it's working. No such claims by DCC Concepts so who knows what to expect.
Might be worth giving the TCS KA1 a try on the DCC Concepts decoder.







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