Which Cheap, Small Locomotive Decoder would accept a Stay-Alive?

[Art Dent]

Hi Folks,

 

I know that the 2-function DCC Concepts ZN6D (at £22.95) will accept a stay-alive (indeed it is packaged with a small stay-alive) but I was wondering if the following decoders would accept a stay-alive and if so, how easy they are to fit (I'm assuming that it is highly likely that some soldering to the decoder's motherboard is required).

 

Hornby 4-function decoder R8249 (at £15.50)

 

Bachmann 4-function decoder 36-566 (at £15.50)

 

Gaugemaster 4-function DCC27 Omni decoder (at £16.95)

 

The decoders have to be small as I am thinking of fitting the decoder into Hornby's R9288 Percy locomotive for my grandson and I'm guessing that space inside will be somewhat at a premium.

 

Best wishes for the festive season and thanks in advance.

 

Art

[NIK]

Hi Folks,

 

I know that the 2-function DCC Concepts ZN6D (at £22.95) will accept a stay-alive (indeed it is packaged with a small stay-alive) but I was wondering if the following decoders would accept a stay-alive and if so, how easy they are to fit (I'm assuming that it is highly likely that some soldering to the decoder's motherboard is required).

 

Hornby 4-function decoder R8249 (at £15.50)

 

Bachmann 4-function decoder 36-566 (at £15.50)

 

Gaugemaster 4-function DCC27 Omni decoder (at £16.95)

 

The decoders have to be small as I am thinking of fitting the decoder into Hornby's R9288 Percy locomotive for my grandson and I'm guessing that space inside will be somewhat at a premium.

 

Best wishes for the festive season and thanks in advance.

 

Art

 

Hi,

 

If your grandson is pretty young is fitting stay alive needed?. Won't he be running it full pelt as his mind works full pelt?. If the track get so dirty the loco wont run then fitting a stay alive will result in the loco not responding to the controller which might be frustrating for a young one.

 

Regards

 

Nick

[RAF96]

Adding stay alives to the Hornby R8249 and TTS decoders has been covered on their forum a few times and yes it does need some skillful soldering in between components on the decoder.

Rob

[Art Dent]

Hi,

 

If your grandson is pretty young is fitting stay alive needed?. Won't he be running it full pelt as his mind works full pelt?. If the track get so dirty the loco wont run then fitting a stay alive will result in the loco not responding to the controller which might be frustrating for a young one.

 

Regards

 

Nick

Hi Nick,

 

He may well indeed run the loco at 'full chat' although he does like to see my 9F slowly trundling around the test layout and has got his head around how to work the NCE PowerCab throttle (not bad for a just-3-year-old).

 

However, I thought I'd fit a stay-alive just in case he crawls the loco across a point and it stalls (the loco I'm thinking of is Hornby's R9288 Percy - which is an 0-4-0 and so may be prone to stalling).

 

There's plenty of room inside Percy (both at the front of the loco above the worm gear and between the chimney and dome and also in the bunker area) to hardwire a small decoder (such as DCC Concepts DCD Z218 decoder) and a stay-alive such as Digitrain's 860009 (which is hardly bigger than a 5p piece).

 

Currently he has Bachmann's train set loco No.49 Stuart (which is a bit of a dog tbh and doesn't do slow running at all well).

 

 

Adding stay alives to the Hornby R8249 and TTS decoders has been covered on their forum a few times and yes it does need some skillful soldering in between components on the decoder.

Rob

Hi Rob,

 

I've been re-thinking and rather than try to solder to the minute tabs on a decoder's motherboard (assuming you can find the correct places to solder that is), I think I'll go for DCC Concepts Z218 decoder (which already has the blue and black stay-alive wires soldered to the decoder motherboard) and so negating the need to (a) find the correct places to solder and (b) having to micro-solder the stay-alive.

 

It is slightly more expensive than the Gaugemaster DCC27 Omni decoder that I purchased this morning from Rails - but not bank-breakingly so.

 

As a general rule I try to stay away from Hornby DCC stuff as there is a lot which isn't NMRA-compliant. I do have one Hornby loco decoder which came in a s/hand DCC-fitted Class 108 DMU in the dummy car - acting as a function-only decoder - but I have no idea as to which model it is nor how many functions.

 

Suffice it to say that both my Prodigy Express system (now replaced) and NCE PowerCab have trouble reading back the CVs on that particular decoder - so it doesn't inspire confidence.

 

R9288 seems easy enough to do, once I've figured out which of the black wires are the track pickups and which are the motor feeds. I suspect that the track pickups go directly to either side of the motor as this 'model' is not marketed as 'DCC Ready'.

 

Will photo-document my exploits at hard-wiring a decoder into Percy for any folks that might follow in my footsteps.

 

I also have R9287 Thomas for him which I will DCC chip and I'll also photo-document that. Again there is a lot of space at the front of the chassis between the dome and chimney as this picture clearly shows https://www.rmweb.co.uk/community/uploads/monthly_06_2015/post-9747-0-41248800-1435492903_thumb.jpg ). There is a small (insulated) screw that holds the motor in place so a piece of 1mm plasticard could be mounted here and the decoder fixed to the top (and perhaps a stay-alive on the underside).

 

All the best Rob and Nick for the festive season.

 

Art

Edited December 20, 2018 by Art Dent

[Sir TophamHatt]

Search "LaisDCC" on ebay.

 

£9.95 + 95p P&P for the decoder.

 

Apparently they are copies of other decoders, but they're cheap and accept a stay alive.  The usual stay alive part is 860007, which is pitifully tiny - not really worth having.  However 860009 is the larger capacity stay alive, but I haven't tested that as I bought stuff to make my own.

 

Good for testing and getting to know what will work and what won't work though.

 

However, I had a strange problem with the 0007 kit stay alive.  When the loco lost contact with power, it would use all the stay alive juice in reverse.  Life got too busy for me to test further but I'm sure someone else on here had the same problem.  Tried with a Zimo stay alive and my own hom ebuilt version - all release their power in the opposite way the loco was originally running.

 

I've ended up buying a Zimo decoder with the stay alive wires attached so I can use my home built version stay alive and not have any funny reversing incidents.

[Art Dent]

Search "LaisDCC" on ebay.

 

£9.95 + 95p P&P for the decoder.

 

Apparently they are copies of other decoders, but they're cheap and accept a stay alive.  The usual stay alive part is 860007, which is pitifully tiny - not really worth having.  However 860009 is the larger capacity stay alive, but I haven't tested that as I bought stuff to make my own.

 

Good for testing and getting to know what will work and what won't work though.

 

However, I had a strange problem with the 0007 kit stay alive.  When the loco lost contact with power, it would use all the stay alive juice in reverse.  Life got too busy for me to test further but I'm sure someone else on here had the same problem.  Tried with a Zimo stay alive and my own home built version - all release their power in the opposite way the loco was originally running.

 

I've ended up buying a Zimo decoder with the stay alive wires attached so I can use my home built version stay alive and not have any funny reversing incidents.

 

Hi STH,

 

Thank you for that - I'd completely forgotten about LaisDCC decoders at about a tenner a pop.

 

If the 860009 is the same as that sold by Digitrains of Lincoln then it has a fair amount of energy storage as it powers my O-gauge Dapol 08 for around 10 sec and the sound for just under a minute.

 

Most decoders seem to have the blue & black stay-alive leads - you say that you make your own stay-alives.

 

Do you use ordinary electrolytics or super-capacitors and if the latter, what size/capacity/voltage.  Do you attempt to fit a balancing circuit at all?

 

Thanks in advance,

 

Art

Edited December 21, 2018 by Art Dent

[Sir TophamHatt]

 

Do you use ordinary electrolytics or super-capacitors and if the latter, what size/capacity/voltage.  Do you attempt to fit a balancing circuit at all?

 

To be honest, I don't know what I used :S

 

I need to write up a proper guide (to help myself in the future too!) but I used:

 

Super Capacitors: https://uk.rs-online.com/web/p/electric-double-layer-capacitors/7637750/

Cooper Bussmann 1F Supercapacitor EDLC -10 → +30% Tolerance Supercap HV Series 2.7V dc Through Hole

 

Diodes: https://www.rapidonline.com/dc-components-1n4001-1a-50v-silicon-rectifier-diode-47-3130

DC Components 1N4001 1A 50V Silicon Rectifier Diode

 

Resistors: https://www.rapidonline.com/truohm-cr-025-100r-carbon-film-resistor-0-25w-pack-of-100-62-0346

TruOhm CR-025 100R Carbon Film Resistor 0.25W - Pack of 100

 

I have no idea what half the stuff means (-10 --> 30%, Through Hole, Carbon Film?) but I'm happy not learning about that at the moment.  If someone gives me a list of things I need, I'm okay buying it and constructing it.

 

I guess I didn't use a balancing circuit?

 

After joining (6 of) them together, it worked as expected.  I used a LaisDCC decoder for testing though I wonder if their own large capacity ones work fine with their own decoders?  They're pretty cheap too.

 

Home made isn't as pretty as commercial ones but I spent about £26 and can make 5 stay alives, so they're about £5 each - much less than the ~£17 the commercial versions command for the size I require.  I bought 100 resistors and 100 diodes (the smallest quantity they did), but only bought 30 capacitors.  I use 6 capacitors in each stay alive so limited to being able to make 5 at the moment.

 

Bought a Zimo decoder with the stay alive wires so I'll be swapping things about and hopefully have a particular loco running sweet.  Just concerned a little though as I read elsewhere that CD motor conversions don't play well with stay alives :/

[Art Dent]

Thanks for the clarification and extra info STH.

 

Don't know what CD motor conversions are (unless you mean the 5v/12v motors from CD drives??)

 

Just concerned a little though as I read elsewhere that CD motor conversions don't play well with stay alives :/

 

Art

[Sir TophamHatt]

Thanks for the clarification and extra info STH.

 

Don't know what CD motor conversions are (unless you mean the 5v/12v motors from CD drives??)

 

 

Just concerned a little though as I read elsewhere that CD motor conversions don't play well with stay alives :/

 

Art

 

Yeah.

Many people convert old Lima (especially) motors to those from old CD drives to improve running.

 

I've done two myself.  The thread about it is here: http://www.rmweb.co.uk/community/index.php?/topic/138001-stay-alive-confusion/

Although I didn't really read it thoroughly so may have got the wrong end of the stick.

Edited December 24, 2018 by Sir TophamHatt

[Art Dent]

Hello folks,

 

Just received a couple of commercial stay-alives and opened them up to have a look-see.

 

First - a single (small-ish) stay-alive

 

 

This contains a 16V 470uF capacitor ...

 

 

and what I'm guessing is a simple resistor/diode charging/discharging circuit..

 

 

I'm a bit worried that this is only a 16V capacitor though!

 

The larger stay-alive is a bit more interesting ...

 

 

It contains four 2.7V 1.0F (yes, 1 Farad) super-capacitors ...

 

 

... and what I think is a dc-dc voltage doubling circuit ...

 

 

I can't identify some of the surface mount components in this circuit - one is labelled 'WG', one is labelled '1P'  and one is labelled 'SH1'.

 

 

I think the component above (labelled 'WG') is a Transient Voltage Suppression Diode (rated 6V as far as I can tell from Googling)

 

 

... and I think that these two are transistors forming an astable circuit??

 

There is also a large 1k5 surface mount resistor.

 

There is also a small (as far as I can tell) unmarked component - a diode or resistor (just underneath the large resistor in the picture below)

 

 

Any ideas what the other components are.  Are my guesses correct?

 

Cheers,

 

Art

Edited December 24, 2018 by Art Dent

[alfsboy]

I use Lais Dcc decoder in all US my brass locos and their  stay alive .I find the DCC concepts stay alive works well too.My switching layout uses insulfrog and stay alive solves all problems .I have a brass shay ,notoriuios for pickup problems ,thats stalls easily but a stay alive will probably solve it all .I will fit as large a version as I can get in .

[Nigelcliffe]

Hello folks,

 

Just received a couple of commercial stay-alives and opened them up to have a look-see.

 

First - a single (small-ish) stay-alive

 

This contains a 16V 470uF capacitor ... 

and what I'm guessing is a simple resistor/diode charging/discharging circuit..

 

I'm a bit worried that this is only a 16V capacitor though!

Yes, that's what I see. About 30p worth of components, at most, and good to 16v. Fine on most small DCC systems, there is a bit of rectifier loss in a decoder, so probably OK at 17 or 18v at the track.

 

 

The larger stay-alive is a bit more interesting ...

 

It contains four 2.7V 1.0F (yes, 1 Farad) super-capacitors ...

 

In series, which is 11v and 0.25F. Which is very over driven, or some circuitry to hold the volts under control (I think the latter).

 

 

... and what I think is a dc-dc voltage doubling circuit ...

 

Doesn't look to have anywhere near enough components to be a doubling circuit. For an example circuit, MERG journal, 2017 winter, page 34 onwards, or the Lenz Power-1 unit (it uses one 2.7v 1F capacitor, a couple of integrated circuits, various other gubbins, etc.. to produce the required voltages). 

 

My guess is its more about regulation of charge/discharge, to keep the voltage OK-ish without over-volting the capacitors.  

 

Try measuring the voltages in/out when its in use, that will give a lot of clues. Power the decoder (no need to run a motor), and put a volt meter on the two leads. What is the volt reading when it is on track power, and what is the reading when track power is removed ?

 

 

- Nigel

[Art Dent]

Yes, that's what I see. About 30p worth of components, at most, and good to 16v. Fine on most small DCC systems, there is a bit of rectifier loss in a decoder, so probably OK at 17 or 18v at the track.

 

 

In series, which is 11v and 0.25F. Which is very over driven, or some circuitry to hold the volts under control (I think the latter).

 

 

Doesn't look to have anywhere near enough components to be a doubling circuit. For an example circuit, MERG journal, 2017 winter, page 34 onwards, or the Lenz Power-1 unit (it uses one 2.7v 1F capacitor, a couple of integrated circuits, various other gubbins, etc.. to produce the required voltages). 

 

My guess is its more about regulation of charge/discharge, to keep the voltage OK-ish without over-volting the capacitors.  

 

Try measuring the voltages in/out when its in use, that will give a lot of clues. Power the decoder (no need to run a motor), and put a volt meter on the two leads. What is the volt reading when it is on track power, and what is the reading when track power is removed ?

 

 

- Nigel

 

Hi Nigel,

 

Totally agree that there doesn't seem to be enough components to be a voltage doubler - however the rwo components marked '1P' and 'SH1' appear to be transistors and as such the basis of a crude astable multivibrator (aka timer).  Most voltage doublers seem to use a 555 timer IC and some diodes.

 

I didn't have the time to figure out/measeure the input/output voltages of the stay-alive.  See this post to see what I have been up to >> http://www.rmweb.co.uk/community/index.php?/topic/140720-fitting-a-decoder-to-Hornby-r9288-0-4-0-percy/?p=3410846

 

Kind regards,

 

Art

[Crewlisle]

I respect all you modellers who have a lot more knowledge of electronics & the technicalities of DCC than I do, but all this technical talk is what put me off DCC in the first place.  When I sat down about 10 years ago & thought about what was required to convert my DC layout to DCC there was not much difference. Reading some of the articles in the model magazines gave the the impression you needed a degree in electronics!  It seems we are going back to repeating this impression.

 

If your layout is laid correctly with live frog points with polarity switching point motors (with which I vehemently disagree!), why do you need stay alive capacitors?  It is another expense & complication which can put people off DCC.  My layout is more or less the same design as I built 45 years ago.  Over the years I have improved the scenery & added to my stock of which the latest addition (curtesy of Father Christmas) is Hornby's Duchess Sir William Stanier. I now have 52 locos (including Thomas the Tank Engine), 12 with sound decoders & the others with Hornby, Bachmann, Lenz or TCS decoders.  Can someone tell me why do I have to spend lots of money & time to add 'stay alive' capacitors to all my locos?

 

I have a total of 30 points.  They were all initially Peco Code 100 Insulfrogs which I converted to Live Frogs & recently replaced some of them with new Peco Code 100 Livefrogs as the originals had worn out!  The only polarity switch of any kind that I have on my layout is for my converted live diamond.  Over the years of operating 'Crewlisle' & attending numerous exhibitions, in all that time the number of point failures or stalls on points I have had I can count on one hand.

 

So why should anyone fit 'stay alive’ capacitors if they follow my layout principles?

 

Peter

[Harlequin]

It's a good question.

 

Here's what Zimo say on the subject:

 

Connecting an external energy source (capacitor) for uninterrupted driving on dead track sections:

Energy storage devices connected to the decoder have many benefits; even very small capacitors as of 100uF have positive effects, larger ones even more so:

• Prevents stalling and flickering lights on dirty track sections or frogs, especially in conjunction with the ZIMO “smart stopping” feature (requires at least 1000μF to be effective)
• Lowers decoder operating temperature especially with low-impedance motors (minimum of 100uF is required)
• when RailCom is used: Eliminates the energy loss created by the “RailCom gap”, reduces motor noise caused by Rail-Com and improves the quality (= legibility) of the RailCom signal (minimum of μF is required)

 

Edit: I guess the use of stay-alive is also something of a personal choice, depending on; what type of locos you run, how fast, how clean your track is, how clean your pickups are and how fussy you are about stalling and sound/light drop-outs.

Edited December 27, 2018 by Harlequin

[Pete the Elaner]

 

So why should anyone fit 'stay alive’ capacitors if they follow my layout principles?

 

 

 

Any method of increasing reliability is good.

Your layout depicts a main line with short trains & steep inclines. This is not to everyone's taste but I do not seen anyone complaining about it (& they shouldn't) so why do you seem to have an issue with others doing things you find unnecessary?

[The Bigbee Line]

I respect all you modellers who have a lot more knowledge of electronics & the technicalities of DCC than I do, but all this technical talk is what put me off DCC in the first place.  When I sat down about 10 years ago & thought about what was required to convert my DC layout to DCC there was not much difference. Reading some of the articles in the model magazines gave the the impression you needed a degree in electronics!  It seems we are going back to repeating this impression.

 

If your layout is laid correctly with live frog points with polarity switching point motors (with which I vehemently disagree!), why do you need stay alive capacitors?  It is another expense & complication which can put people off DCC.  My layout is more or less the same design as I built 45 years ago.  Over the years I have improved the scenery & added to my stock of which the latest addition (curtesy of Father Christmas) is Hornby's Duchess Sir William Stanier. I now have 52 locos (including Thomas the Tank Engine), 12 with sound decoders & the others with Hornby, Bachmann, Lenz or TCS decoders.  Can someone tell me why do I have to spend lots of money & time to add 'stay alive' capacitors to all my locos?

 

I have a total of 30 points.  They were all initially Peco Code 100 Insulfrogs which I converted to Live Frogs & recently replaced some of them with new Peco Code 100 Livefrogs as the originals had worn out!  The only polarity switch of any kind that I have on my layout is for my converted live diamond.  Over the years of operating 'Crewlisle' & attending numerous exhibitions, in all that time the number of point failures or stalls on points I have had I can count on one hand.

 

So why should anyone fit 'stay alive’ capacitors if they follow my layout principles?

 

Peter

Peter,

 

I think you should 'bottle your secret' and sell it at exhibitions.  Seriously there are a couple of different viewpoints on the railhead conditions, some people keep it dry and clean regularly, others clean and then apply either graphite or a conducting oil of some kind.  I favour the dry and clean principle.  Some people have problems with crud build up on wagon wheels, especially plastic wheels and have to resort to cleaning sessions.

 

If there is a loss of continuity the sound system can see that and then initiates a re-start.  The stay alive will eliminate that effect.  It also allows the use of non switched crossings if desired and avoids switches etc.  It's up to the user obviously.  My view is that if I'm investing in a sound decoder I would like the benefits of the stay alive, working on the 'why spoil the ship for a happorth of tar' principle.

 

Best wishes for the new year

 

Ernie

[njee20]

Any method of increasing reliability is good.

Your layout depicts a main line with short trains & steep inclines. This is not to everyone's taste but I do not seen anyone complaining about it (& they shouldn't) so why do you seem to have an issue with others doing things you find unnecessary?

I have to agree with this. Surely you can see that not everyone wants trains whipping around at mainline speeds, some may want small locos to creep over pointwork without stalling.

 

It’s nothing to do with complexity of DCC either, it’s about some people having an interest in a different facet of the hobby to you. The discussion could building a PWM controller and the requisite components, that wouldn’t make DC control something that requires an electronics degree, it just makes complex electronics something you have no interest in or understanding of. Nothing wrong with that, but why do you feel the need to be so disparaging?

[Crosland]

Hi Nigel,

 

Totally agree that there doesn't seem to be enough components to be a voltage doubler - however the rwo components marked '1P' and 'SH1' appear to be transistors and as such the basis of a crude astable multivibrator (aka timer).  Most voltage doublers seem to use a 555 timer IC and some diodes.

 

 

 

There aren't enough components to be an astable, unless its a double sided board. You would need capacitors as well.One of the "transistors" only has connections to two pins so is mre likely a diode. The component marked WG is in series with one of the supply wires so will be a normal diode. As Nigel says, it's just a simple control circuit, I'm guessing a zener plus transistor to regulate the voltage. 

[Art Dent]

I have to agree with this. Surely you can see that not everyone wants trains whipping around at mainline speeds, some may want small locos to creep over pointwork without stalling.

 

Exactly.

 

As per my original post, I want to fit a small, cheap-ish decoder plus stay-alive into my Grandson's 0-4-0 Percy so that he can (a) run it slowly if required and (b) crawl across pointwork without the danger of stalling.

 

Being an 0-4-0 albeit with pickups on all wheels, it is most likely to stall on a point - and that would like as not be in the most awkward part of the layout!

 

Art

[Crewlisle]

Any method of increasing reliability is good.

Your layout depicts a main line with short trains & steep inclines. This is not to everyone's taste but I do not seen anyone complaining about it (& they shouldn't) so why do you seem to have an issue with others doing things you find unnecessary?

 

Pete,

 

I am sorry my article came across the wrong way.  I accept that the basis of our hobby is that everyone has their own preferences about their preferred scales, settings & eras.  I apologise if I have upset anyone.  

 

With reference to my own layout 'Crewlisle', of the 30 points quoted in my Comment No.14 half of them are on the high level where the 6 coach expresses & freight trains are assembled, shunted & light engine movements take place - all obviously at slow speeds.

.

 

 

It's a good question.

 

Here's what Zimo say on the subject:

 

Connecting an external energy source (capacitor) for uninterrupted driving on dead track sections:

Energy storage devices connected to the decoder have many benefits; even very small capacitors as of 100uF have positive effects, larger ones even more so:

• Prevents stalling and flickering lights on dirty track sections or frogs, especially in conjunction with the ZIMO “smart stopping” feature (requires at least 1000μF to be effective)
• Lowers decoder operating temperature especially with low-impedance motors (minimum of 100uF is required)
• when RailCom is used: Eliminates the energy loss created by the “RailCom gap”, reduces motor noise caused by Rail-Com and improves the quality (= legibility) of the RailCom signal (minimum of μF is required)

 

Edit: I guess the use of stay-alive is also something of a personal choice, depending on; what type of locos you run, how fast, how clean your track is, how clean your pickups are and how fussy you are about stalling and sound/light drop-outs.

 

 

Phil,

 

Thanks for that extract from Zimo.  It is the first simple quote I have seen as to why it is a good idea to fit stay alive capacitors.  However, because I have not had any real problems, I am certainly not going to retro fit my 52 locos with stay alive capacitors.

 

Peter

Edited December 31, 2018 by Crewlisle

[Sir TophamHatt]

If your layout is laid correctly with live frog points with polarity switching point motors (with which I vehemently disagree!), why do you need stay alive capacitors?

 

Can someone tell me why do I have to spend lots of money & time to add 'stay alive' capacitors to all my locos?

 

So why should anyone fit 'stay alive’ capacitors if they follow my layout principles?

 

As has been touched on, you don't need to do anything

 

I have a Lima 156 which the pickups are awful.  The loco will move along but it's stuttery all over the place.  I've added lights to make things even more fun, and either I have, or it's on the list to convert to a CD motor.

I'm hoping a stay alive will help this loco run a little more stable.

I could spend time messing about with creating better pickups from all wheels, but I suspect that is the same as building a stay alive in that I still have to perform some action to get reliable running.

Building my own stay alives has come in at about £5 per one, so not that expensive.

 

But you do raise a valid point.

 

Sometimes, not everyone is able to create a model railway that is reliable enough, as many people rush or have time constraints to get things done.  It's not an excuse for not doing things reliably, but is a remedy when things haven't been done reliably.

My layout was built for reliability... until I started rushing.  Now I have a set of points that don't throw properly, two places where a train can will derail if it's over a certain speed, and a hill that is a little too steep at the angle with the board, so some locos get stuck.  Funny as the (long) MK3 coach (which I used to test) is fine, yet a Class 68 gets stuck!

Edited January 4, 2019 by Sir TophamHatt

[Sir TophamHatt]

My efforts of a home made stay alive... think I may have gone overboard with capacity!

 

[YouTube]

[/YouTube]

[Art Dent]

Hi STH

 

There is a tendency - and I know that I am guilty here - of going for the largest capacity/energy storage possible.

 

However, in reality, all we really need is perhaps a half-second or second at most.  That's what I'm trying to achieve with my self-build units.  However, it seems to be that you can source small electrolytic or tantalum capacitors which give fractions of a second of power, or 1F and over super-capacitors which give tens of seconds.  There doesn't at present (at least I haven't found any yet for a reasonable price) anything that gives around 1/4 sec to 1 sec of running time.

 

Some decoders allow you to set how much stay-alive power (in seconds?) you can use but there hardly seems to be worthwhile fabricating a stay-alive that gives (say) 20 seconds of power and adjust the decoder so that you use less than 5% of the available energy.

 

There is a danger of the loco hitting a dead-spot with a large capacity stay-alive fitted to just carry on going - perhaps into the rear of some stationary wagons/coaches or the buffers etc.  The stay-alive will keep the decoder powered and obeying the last instruction it received.  What it can't do is keep the loco powered whilst continuing to receive signals from the DCC Control Station.

 

Given that stay-alives have been around in one form or another for about the last 10-15 years (to my knowledge) you would have thought that manufacturers would be able to offer a range of solutions rather than (using the LaisDCC units 39007 and 39009 as examples) very small or very large.

 

Certainly seems that you've got a lot more than you need there - unless that was what you were aiming for of course.

 

Rgds

 

Art

Edited January 6, 2019 by Art Dent

[Sir TophamHatt]

Certainly seems that you've got a lot more than you need there - unless that was what you were aiming for of course.

 

More than I expected but I don't think I can have any less because of the cap voltages.

That 156 (which is now on ebay as I couldn't get it to a stage I liked) is a bit of a poor runner, but that's mainly because of the pickups.  I have the stay alive components, but no way to improve the pickup reliability so the former it is.

 

Strangely, and I need to test more, I fitted the same chip and stay alive to another loco, which when losing power, kept the lights on but the motor stopped straight away.  Need to test but the SA wires came off the Zimo chip :/