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Fabrication of Small Capacity DIY Locomotive Stay-Alive


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In a previous thread, I had discussed my thoughts on fabricating a small stay-alive unit using super-capacitors.

 

This was prompted by me buying my 3-y-o grandson a 'Percy' 0-4-0 locomotive (and me not wanting it to stall on pointwork it only being a SWB 0-4-0).

 

Over the last couple of weeks I have refined my ideas and the design whilst trying to source the components.

 

When fitting a stay-alive - one if the biggest dangers (as I see it now) is to go for 'The Best Bang for Your Buck' - in other words, the biggest stay-alive you can fit (in terms of capacity) in a given space and for reasonable cost.

 

As 'Percy' isn't what you'd call a 'highly detailed' nor expensive model, so I didn't want to fit an overly-expensive decoder or stay-alive.  This lead me to buying and trying a LaisDCC 860012 NEM651 + 2 stay-alive wires decoder and two LaisDCC Stay-alives ('small' 860007 and 'large' 860009).  The decoder is less than £10, the small stay-alive (don't bother with it) is £3 and the large stay-alive (huge over-kill) is £9.00

 

More about the LaisDCC Decoder and Stay-Alives later.

 

To make sure that you don't encounter problems (like the loco taking off at high speed or running backwards - or both) when track power is cut, disable DC running in CV29

 

Anyway, to the main course ...

 

I had managed to find some 470,000uF, 5.5V rectangular supercapacitors.  Three wired up in series would give a 16.5V, 157,000uF unit.

 

Fabrication of the 15.7mF (15700uF) stay-alive unit.
 
My aim was to arrange these rectangular capacitors side-by-side so first I bent the negative and positive of adjacent capacitors at right-angles:
 
31787311127_483fe2a410_k.jpg
 
The legs were then angled slightly before the legs were cut to length and the capacitors were superglued together:
 
45813144385_4956315f92_k.jpg
 
The first two capacitors were super-glued together ready to be soldered:
 
45813143785_605bef9e13_k.jpg
 
Then three capacitors were glued together ready to be soldered in series.  This gives a maximum voltage that the stay-alive can handle of 16.5V and a capacity of 15700uF.
 
It also makes for a relatively compact unit.
 
46676086112_6f4daef367_k.jpg
 
Another view of the 15700uF stay-alive unit:
 
31787309797_1a726477eb_k.jpg
 
Checking for fit inside Percy's bunker (it only just fits):
 
45813142555_f1ccfb5be4_k.jpg
 
Capacitors soldered together and the discharging diode and charging resistor soldered:
 
31787308867_9bee8eb04f_k.jpg
 
Another view:
 
46676084592_37faa5e1e1_k.jpg
 
All-important insulation added:
 
46676084312_fd4c6b0da0_k.jpg
 
First testing (using cheap LaisDCC decoder rather than anything more expensive and some very Heath-Robinson wiring) as currently fitted to Thomas:
 
45813140025_db429855d9_k.jpg
 
I ran Thomas ran for 5 mins at 75% throttle to ensure stay-alive is fully charged (not having previously calculated the time that a full charge would take).
 
Upon disconnecting track power (using the centre-off switch you can see on the white panel) ...
 
... NOTHING!
 
No indication at all that the stay-alive is doing anything at all.  The wheels just stopped dead.
 
So, is the stay-alive not charging or is it a problem with the LaisDCC Decoder (and yes, DC running has already been turned off in CV29).
 
I thought it was the decoder, so onto Percy with the DCC Concepts Zen 218 decoder ...
 
Percy on the rolling road with the stay-alive:
 
46004852284_ff23474ff7_k.jpg
 
Video here (not sure if I can link a video - so here's the YouTube link: https://www.youtube-nocookie.com/embed/9hhorqaSWkI)
 
So yes, the LaisDCC Decoder doesn't play nicely with my stay-alive.
 
When the LaisDCC Decoder had earlier been fitted to the smaller of the two LaisDCC stay-alive units (860007), it did nothing.
 
Connecting the larger 860009 unit certainly had an effect but on removal of track power - the loco's wheels (thankfully running on the rolling road) rand backwards at high speed.
 
I'm coming to the conclusion that that particular decoder dosn't like any stay-alives!  I guess it proves that you get what you pay for.
 
Anyway ...
 
The stay-alive with heat-shrink applied (makes sure there is no possibility for short circuits):
 
46004851564_7efe19c637_k.jpg
 
Decoder and stay-alive installed in Percy's bunker and cab and held in place by black-tack (really useful stuff that):
 
46004851124_a779a0ecfb_k.jpg
 
The positives
 
As you can see, the stay-alive a) runs, b) runs in the right direction! c) lasts for around 1/4 to 1/3 sec (enough to get it over a dead frog)
 
The one negative
 
Only runs for around 1/4 to 1/3 sec and just a couple of cm.
 
However, this is kind of what I was after.  Possibly (if there is room) two of these could be wired in parallel thus doubling the run-time.
 
Cost?
 
Aside from the various different sizes of heat-shrink which I had anyway ...
 
1x 1N4007 rectifying diode (1kV, 1A - although a 1N4001 which is 50V, 1A would do) - cost 8p (bag of 50 for less than £4)
1x 100-ohm 1%, 1/4 watt metal film resistor - 1p??  No idea really as I bought a 'bag' of mixed resistors (10 of each of 30 different values for 99p)
3x 47000uF super-capacitors at 40p each
 
So, all-up around £1.30-ish
 
Beats £3 for the LaisDCC 860007 (which did nothing) and £9 for the LaisDCC 860009 (which lasts for 25 seconds but runs in reverese and is way over the top).
 
Plus, there was the fun of the journey as well  :mosking:
 
If you have managed to get this far, I hope you have enjoyed reading about this and maybe this will encourage you to try fabricating your own stay-alive units.
 
Cheers,
 

 

Art
Edited by Art Dent
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  • 3 weeks later...

 

Plus, there was the fun of the journey as well  :mosking:
 
If you have managed to get this far, I hope you have enjoyed reading about this and maybe this will encourage you to try fabricating your own stay-alive units.
 
Cheers,
 

 

Art

 

art,

 

Thanks, exactly the issue I've been trying to address. Friend of mine just built me a similar device but only 11v, I think the Blue / Black SA output is around 12V on my setup. Comforting to know it all works on a DCC Concepts chip,

 

Colin

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On 1/29/2019 at 6:45 AM, BWsTrains said:

art,

 

Thanks, exactly the issue I've been trying to address. Friend of mine just built me a similar device but only 11v, I think the Blue / Black SA output is around 12V on my setup. Comforting to know it all works on a DCC Concepts chip,

 

Colin

 

Hi Colin,

 

I'd worry using your mate's stay-alive on your system.  An 11V unit (two 5.5V caps?) on a 12V system is asking for trouble IMHO.  If the stay-alive does indeed use two 5.5V capacitors (I'm going with super-capacitors here) then there is a fair amount of energy stored in them and most super-capacitors are not tolerant at all to over-voltage.

 

There is no reason why a stay-alive shouldn't work with the DCC Concepts decoder - it is already set up to accept their own small stay-alive (which has no measurable effect as far as I can see).

 

The LaisDCC decoder I used should also work as it too comes pre-wired with the black and blue stay-alive wires.

 

However, I found that the small 860007 stay-alive also did nothing whilst the larger 860009 stay-alive certainly had a measurable effect in keeping the motor turning but at high speed and backwards!

 

I'm possibly being unfair to the LaisDCC decoder and large stay-alive here as when they were tested, I hadn't turned off DCC running in CV29 (to turn DC running off clear bit 2 in CV29) and when testing my stay-alive unit although I'd turned off DC running on both the LaisDCC cnd DCC Concepts chips, I'd misplaced the LaisDCC 860009 stay-alive (it was hiding under a piece of paper) so couldn't re-try it.

 

I also need to check if Railcom is enabled as apparently this can have an effect when decoders are running on stay-alive power.

 

This useful link shows a table of different values for CV29 and their effect >> https://tonystrains.com/news/cv29-look-up-table/ - although it neglects to mention Railcom (which is controlled by bit 3 (decimal value = 8) of CV29.

 

The highlighted line in the table (decimal value 6) means 28/128 speed steps, DC running, forward running and short addresses are all set to ON.  To switch DC running off, program CV29 with the value 2.  With CV29 set to 6, Railcom is also disabled.

 

The 2mm Scale Association provide a handy on-line calculator for CV29.  Just tick (or clear) the relevant boxes in column 3 and it gives you the required value to program into CV29 >> http://www.2mm.org.uk/articles/cv29 calculator.htm

 

Hope this helps.

 

Art

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Art,

 

Thanks for the concern but my "mate" knows his stuff. The 5.5V (25,000uF) capacitors he used were in series and each had a 5V Zener Diode to voltage regulate their charging. Fully charged they duly showed a Voltage just under 10V.

 

What the experiment did disclose is the fundamental weakness of using low cost Super-Capacitors of the type I deployed. Unless you pay quite a lot it appears you may be getting a device with a high ESR (or so i've been told) and hence a very limited ability to deliver any decent current. The devices my friend used were rated to operate at under 1mA and so were not up to the job, something he realised a bit too late. They worked well but after a number of cycles their storage capacity failed, just about the time he emailed me to predict that occurrence!

 

Not all was lost, I pulled off the other relevant components and used 4400uF of electrolytic capacitors. These worked a charm delivering about 60% of 1 wheel turn or 40mm of run on, more than enough for my needs on a Class 48xx.

 

If you want more storage, then go to "designed for purpose" Super Caps from a specialist DCC supplier. these will deliver the required currents but are not cheap.

 

Do you know the rate current for the Caps you used?

 

 

Colin

 

Edited by BWsTrains
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11 hours ago, BWsTrains said:

Do you know the rate current for the Caps you used?

 

Colin

 

 

Hi Colin,

 

Sadly, no I don't.  Possibly a Google search for "470000uF", "5.5V" and "Tokin" will turn up the specs?  The NEC Part No. is FM0H473ZFTP

 

This link has technical details (I note there is a 0.1F version, part number FM0H104ZF or FM0H104ZFTP ) >> link

 

These 0.1F super-capacitors are available from RS Components (RS Stock No. 135-6160 ) >> link for £1.28 each

 

Hope this helps.

 

Art

Edited by Art Dent
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1 hour ago, Art Dent said:

 

Hi Colin,

 

Sadly, no I don't.  Possibly a Google search for "470000uF", "5.5V" and "Tokin" will turn up the specs?  The NEC Part No. is FM0H473ZFTP

 

This link has technical details (I note there is a 0.1F version, part number FM0H104ZF or FM0H104ZFTP ) >> link

 

These 0.1F super-capacitors are available from RS Components (RS Stock No. 135-6160 ) >> link for £1.28 each

 

Hope this helps.

 

Art

Not that hard!

 

You'll see below you only needed to get to p4 of your link to learn that the FM series you used are rated for "uA order back-up". Your loco will require 30-60mA!

 

Colin

 

215935472_Capture-tokinspec.JPG.3ec000a35375c0b99e02329ce713ec8a.JPG

 

 

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Hi Colin,

 

I know that now.  My initial reply was accurate as I didn't know - I then went trawling for specs and found the links I posted in the edited thread.

 

It would explain why the stay-alive that I've fabricated and fitted to Percy only moves the motor a small amount (and at much reduced speed).

 

Thanks for the 'heads up' anyhow.  Looks like none of these really deliver "large" currents in the 100's mA range.

 

The FME0H473ZF 5.5V 470000uF super-cap offers 0.071mA (or 71uA) and similarly the 5.5V, 0.1F FMR0H104ZF super-cap only offers twice this at 0.15mA (or 150uA) so neither appear suitable for motors.

 

Art

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  • 4 weeks later...

Too bad I didn't read this informative topic before I bought cheap supercapacitors...

 

I am using LaisDCC decoders and if I understand right the question whether one can assemble his own stay alive module remains unanswered.  LaisDCC claims that "(...) this decoder only support our own brand LaisDcc 860007 Stay Alive kits (...)".  Is this real or just a retail trick?

 

LaisDCC is pretty shadowy DCC producer and despite his products work fine it is next to impossible to get relevant characteristics and information.  Also, I just can't understand what is stay alive module, if not a capacitor with the support resistor-diode circuit.  What do you think?

 

Anyways, I did some research and found out this supercapacitor with a reasonable price and fairly low ESR (equivalent series resistance):

 

https://www.aliexpress.com/item/2pcs-20pcs-0-47F-3-6V-ELNA-DBS-Series-13-5X7-5mm-3-6V0-47uF-Low/32966714946.html

 

Assuming four capacitors are put into series, that is 3V and 25 Ohm ESR per capacitor, this capacitors should give current of about 120 mA.  And with huge capacity of about 120mF, it would provide that current for hefty 12s.   By the way, typical value for ESR for classical capacitors is only 0.1Ohm, theoretically giving currents up to 120A!

 

I searched also standard electronic providers, but couldn't find anything better; if reasonably cheap, supercapacitors have the ESR of about 20 Ohms or more.  So in the end there are only two choices: using supercapacitors with 50 times capacity and limited output current or classical capacitors with practically unlimited output current and 1/50 capacity.  I didn't find anything in between.

 

But in the end, how much time does one really need for a stay alive module?  Modest locomotive speed is in order of few centimeters per second, which means that classical 2.2mF capacitor could provide 300mA for about 0.1s, corresponding to few millimeters mode.  Isn't that enough?

 

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The only other interesting thing that I could find is this one:

 

https://www.digikey.si/product-detail/en/illinois-capacitor/105DER2R5SFN/105DER2R5SFN-ND/5410532

 

If you put five in series, you get 5A top current and 200mF capacity, which corresponds to 8s @ 300mA.  The problem is the size of the whole pack, approx. 8mm x 14mm x 40mm.  Minimum order: 12 pieces for 4 EUR (without P&P).

Edited by pygmalion
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1 hour ago, pygmalion said:

 

LaisDCC is pretty shadowy DCC producer and despite his products work fine it is next to impossible to get relevant characteristics and information.  Also, I just can't understand what is stay alive module, if not a capacitor with the support resistor-diode circuit.  What do you think?

 

Just a marketing gimmick.  As you say, a stay-alive is simply a capacitor (or bank oc capacitors - usually in series) plus a charging resistor (to limit the in-rush current) and which may (or may not) include a resistor/diode balancing circuit.

 

That's all the LaisDCC modules are anyway (I know, I bought the large (860009) and small (860007) stay-alives and cut the heat-shrink off them)!

 

My efforts to get the LaisDCC decoder I had (newly-purchased) with the small stay-alive proved fruitless. There was no discernable difference between having the stay-alive connected to the decoder or not.

 

The large LaisDCC stay-alive (860009) certainly had an effect - of making the loco motor run at high-speed and in reverse the moment track power was cut, powering the loco for around 22 seconds.  Good job it was on a rolling road.

 

This was with DC-running not switched off via CV29.  I didn't bother testing again after disabling DC running, it may have sorted this particular problem out.

 

1 hour ago, pygmalion said:

Assuming four capacitors are put into series, that is 3V and 25 Ohm ESR per capacitor, this capacitors should give current of about 120 mA.  And with huge capacity of about 120mF, it would provide that current for hefty 12s.   By the way, typical value for ESR for classical capacitors is only 0.1Ohm, theoretically giving currents up to 120A!

 

FOUR SUPER-CAPACITORS IN SERIES @ 3V each should not be exposed to the 14V DCC rail supply, nor indeed the 'rectified' output of a decoder which can be over 13.5V.

 

1 hour ago, pygmalion said:

I searched also standard electronic providers, but couldn't find anything better; if reasonably cheap, supercapacitors have the ESR of about 20 Ohms or more.  So in the end there are only two choices: using supercapacitors with 50 times capacity and limited output current or classical capacitors with practically unlimited output current and 1/50 capacity.  I didn't find anything in between.

 

You seem to be able to get super-capacitors that give you very brief fractions of a second, or tens of seconds - but nothing inbetween.

 

1 hour ago, pygmalion said:

But in the end, how much time does one really need for a stay alive module?  Modest locomotive speed is in order of few centimeters per second, which means that classical 2.2mF capacitor could provide 300mA for about 0.1s, corresponding to few millimeters mode.  Isn't that enough?

 

 

That's all I require certainly.

 

Art

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19 hours ago, pygmalion said:

But in the end, how much time does one really need for a stay alive module?  Modest locomotive speed is in order of few centimeters per second, which means that classical 2.2mF capacitor could provide 300mA for about 0.1s, corresponding to few millimeters mode.  Isn't that enough?

 

It's not really about how long in time for me though.

If I have the space and components to make a stay alive that just so happens to run for 10-20 seconds, that's great.  I'd certainly be aiming for something more than the tiny 470 capacity you get with many stay alives (like Zimo!).

No.  Stay alives aren't the answer for dirty track.  But if they provide a fairly decent solution then that's the aim surely?

 

I have three locos that simply don't run very well at low speed.

 

Two have older motors that I can't replace.

The other has a nice new CD motor but I think the wheels and pickups aren't that great, so the stay alive doesn't have that much of an effect at the moment.  But too busy to do some real testing.  They're all long term projects anyway.

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On 04/03/2019 at 19:03, Art Dent said:

 

Just a marketing gimmick.  As you say, a stay-alive is simply a capacitor (or bank oc capacitors - usually in series) plus a charging resistor (to limit the in-rush current) and which may (or may not) include a resistor/diode balancing circuit.

 

FOUR SUPER-CAPACITORS IN SERIES @ 3V each should not be exposed to the 14V DCC rail supply, nor indeed the 'rectified' output of a decoder which can be over 13.5V.

 

 

Thank you for your information about marketing gimmick.  I suspected so, but it is easier when I have first-hand confirmation.  I will try using five (not four) pieces of this capacitor in series (I have realized that for the previous one minimum order is 12000 pieces...):

 

https://www.digikey.si/product-detail/en/illinois-capacitor/DGH105Q2R7/1572-1758-ND/7387508

 

I will let you know the result.

 

I think 5 x 2.7 = 13.5 is enough for my use, after all I am powering my DCC controller with 12V.  But even if I powered my controller with 14V, I could still shield my capacitors with 12V Zener in parallel, wouldn't I?

 

Now, one digression question: Is there a reason to power DCC controller with more than 12V, say 14V?  I am using Pi-SPROG One and I was reluctant to use more than 12V, because more than 12V is not safe for locomotive motors.  Producer of the Pi-SPROG told me it is OK to use more than 12V, as far as DCC controller is concerned.

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On 08/03/2019 at 17:18, pygmalion said:

Now, one digression question: Is there a reason to power DCC controller with more than 12V, say 14V?  I am using Pi-SPROG One and I was reluctant to use more than 12V, because more than 12V is not safe for locomotive motors.  Producer of the Pi-SPROG told me it is OK to use more than 12V, as far as DCC controller is concerned.

 

*shrugs* No idea.

 

The decoder will deliver an apporpriate voltage to the motor, so I wouldn't worry.

 

My NCE system wall-wart (the DC plug-in power supply) says that it outputs 13.8V at 1.8A

 

Art

 

 

Edited by Art Dent
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On 08/03/2019 at 17:18, pygmalion said:

 

Now, one digression question: Is there a reason to power DCC controller with more than 12V, say 14V?  I am using Pi-SPROG One and I was reluctant to use more than 12V, because more than 12V is not safe for locomotive motors.  Producer of the Pi-SPROG told me it is OK to use more than 12V, as far as DCC controller is concerned.

 

It depends on what you want. If 12V gives a realistic/desired top speed for all your locos then it's fine.

 

If any loco is too slow than you need to increase the track voltage.

 

The motor is isolated from the track voltage by the decoder.

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On 14/03/2019 at 11:54, Crosland said:

 

It depends on what you want. If 12V gives a realistic/desired top speed for all your locos then it's fine.

 

If any loco is too slow than you need to increase the track voltage.

 

The motor is isolated from the track voltage by the decoder.

 

This confuses me even more.  If decoder makes sure that the motor is never provided more than 12V, it is only important that supply voltage is more than 12V.  12V or 14V should make no difference (apart from the diminutive drop of voltage due to controller and decoder electronics).  If supply voltage is increased from, say, 13V to 14V, that should make no difference, as I understand that.

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On 17/03/2019 at 12:06, pygmalion said:

 

This confuses me even more.  If decoder makes sure that the motor is never provided more than 12V, it is only important that supply voltage is more than 12V.  12V or 14V should make no difference (apart from the diminutive drop of voltage due to controller and decoder electronics).  If supply voltage is increased from, say, 13V to 14V, that should make no difference, as I understand that.

 

I didn't say that that the motor is never provided more than 12V. If you turn the throttle up full then the motor will see, more or less, the full track voltage.

 

So, if 12V with full throttle gives you an acceptable top speed, you don't need more.

 

If 12V at full throttle is too slow, you need to increase the track voltage, being careful not to go too high for the motor.

 

If the track voltage is too high for some locos (i.e. they run too fast at full throttle) then you can adjust the decoder to limit the top speed. Without going into detail of how they do this, in effect they see a lower maximum voltage. This could be more or less than 12 V.

 

Whilst models may be nominally 12V, I am sure there are many DC controllers that output (or are capable of) more than 12V.

 

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  • 1 year later...
On 14/01/2019 at 06:38, Art Dent said:

In a previous thread, I had discussed my thoughts on fabricating a small stay-alive unit using super-capacitors.

 

This was prompted by me buying my 3-y-o grandson a 'Percy' 0-4-0 locomotive (and me not wanting it to stall on pointwork it only being a SWB 0-4-0).

 

Over the last couple of weeks I have refined my ideas and the design whilst trying to source the components.

 

When fitting a stay-alive - one if the biggest dangers (as I see it now) is to go for 'The Best Bang for Your Buck' - in other words, the biggest stay-alive you can fit (in terms of capacity) in a given space and for reasonable cost.

 

As 'Percy' isn't what you'd call a 'highly detailed' nor expensive model, so I didn't want to fit an overly-expensive decoder or stay-alive.  This lead me to buying and trying a LaisDCC 860012 NEM651 + 2 stay-alive wires decoder and two LaisDCC Stay-alives ('small' 860007 and 'large' 860009).  The decoder is less than £10, the small stay-alive (don't bother with it) is £3 and the large stay-alive (huge over-kill) is £9.00

 

More about the LaisDCC Decoder and Stay-Alives later.

 

To make sure that you don't encounter problems (like the loco taking off at high speed or running backwards - or both) when track power is cut, disable DC running in CV29

 

Anyway, to the main course ...

 

I had managed to find some 470,000uF, 5.5V rectangular supercapacitors.  Three wired up in series would give a 16.5V, 157,000uF unit.

 

Fabrication of the 15.7mF (15700uF) stay-alive unit.
 
My aim was to arrange these rectangular capacitors side-by-side so first I bent the negative and positive of adjacent capacitors at right-angles:
 
31787311127_483fe2a410_k.jpg
 
The legs were then angled slightly before the legs were cut to length and the capacitors were superglued together:
 
45813144385_4956315f92_k.jpg
 
The first two capacitors were super-glued together ready to be soldered:
 
45813143785_605bef9e13_k.jpg
 
Then three capacitors were glued together ready to be soldered in series.  This gives a maximum voltage that the stay-alive can handle of 16.5V and a capacity of 15700uF.
 
It also makes for a relatively compact unit.
 
46676086112_6f4daef367_k.jpg
 
Another view of the 15700uF stay-alive unit:
 
31787309797_1a726477eb_k.jpg
 
Checking for fit inside Percy's bunker (it only just fits):
 
45813142555_f1ccfb5be4_k.jpg
 
Capacitors soldered together and the discharging diode and charging resistor soldered:
 
31787308867_9bee8eb04f_k.jpg
 
Another view:
 
46676084592_37faa5e1e1_k.jpg
 
All-important insulation added:
 
46676084312_fd4c6b0da0_k.jpg
 
First testing (using cheap LaisDCC decoder rather than anything more expensive and some very Heath-Robinson wiring) as currently fitted to Thomas:
 
45813140025_db429855d9_k.jpg
 
I ran Thomas ran for 5 mins at 75% throttle to ensure stay-alive is fully charged (not having previously calculated the time that a full charge would take).
 
Upon disconnecting track power (using the centre-off switch you can see on the white panel) ...
 
... NOTHING!
 
No indication at all that the stay-alive is doing anything at all.  The wheels just stopped dead.
 
So, is the stay-alive not charging or is it a problem with the LaisDCC Decoder (and yes, DC running has already been turned off in CV29).
 
I thought it was the decoder, so onto Percy with the DCC Concepts Zen 218 decoder ...
 
Percy on the rolling road with the stay-alive:
 
46004852284_ff23474ff7_k.jpg
 
Video here (not sure if I can link a video - so here's the YouTube link: https://www.youtube-nocookie.com/embed/9hhorqaSWkI)
 
So yes, the LaisDCC Decoder doesn't play nicely with my stay-alive.
 
When the LaisDCC Decoder had earlier been fitted to the smaller of the two LaisDCC stay-alive units (860007), it did nothing.
 
Connecting the larger 860009 unit certainly had an effect but on removal of track power - the loco's wheels (thankfully running on the rolling road) rand backwards at high speed.
 
I'm coming to the conclusion that that particular decoder dosn't like any stay-alives!  I guess it proves that you get what you pay for.
 
Anyway ...
 
The stay-alive with heat-shrink applied (makes sure there is no possibility for short circuits):
 
46004851564_7efe19c637_k.jpg
 
Decoder and stay-alive installed in Percy's bunker and cab and held in place by black-tack (really useful stuff that):
 
46004851124_a779a0ecfb_k.jpg
 
The positives
 
As you can see, the stay-alive a) runs, b) runs in the right direction! c) lasts for around 1/4 to 1/3 sec (enough to get it over a dead frog)
 
The one negative
 
Only runs for around 1/4 to 1/3 sec and just a couple of cm.
 
However, this is kind of what I was after.  Possibly (if there is room) two of these could be wired in parallel thus doubling the run-time.
 
Cost?
 
Aside from the various different sizes of heat-shrink which I had anyway ...
 
1x 1N4007 rectifying diode (1kV, 1A - although a 1N4001 which is 50V, 1A would do) - cost 8p (bag of 50 for less than £4)
1x 100-ohm 1%, 1/4 watt metal film resistor - 1p??  No idea really as I bought a 'bag' of mixed resistors (10 of each of 30 different values for 99p)
3x 47000uF super-capacitors at 40p each
 
So, all-up around £1.30-ish
 
Beats £3 for the LaisDCC 860007 (which did nothing) and £9 for the LaisDCC 860009 (which lasts for 25 seconds but runs in reverese and is way over the top).
 
Plus, there was the fun of the journey as well  :mosking:
 
If you have managed to get this far, I hope you have enjoyed reading about this and maybe this will encourage you to try fabricating your own stay-alive units.
 
Cheers,
 

 

Art

Hi can I ask what polarity should the cap be fitted to the DCC concepts blue and black wires? is the blue positive and the black negative?. Cheers T

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1 hour ago, posneg6 said:

Thanks for those links . I've seen them both. I still need to know what the the polarity of the blue and black wires are from my DCC concets decoder . It says nothing about that in their 12 page decoder manual 

 

Hi, Sorted by using  my multi meter, Blue is positive black is negative on the DCC TS4sax 

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  • 5 months later...

OK folks, I have finally reached stay-alive experiments.

I made 4400uF stay-alive (2x2200uF) for my 860014 LaisDCC decoder with black and blue stay-alive wires.

I also forgot to turn off DC (CV29 = 38) so the decoder was just acting all crazy. After I turned off DC (CV29 = 34), the decoder works normally, but the effect of stay-alive is ZERO. After the line loses power, the motor and/or LED stop immediately.

I know that the motor should only work for a fraction of a second, but I expected LED to work for at least a second.

I checked my stay-alive against LED and LED is kept on for a few seconds. I measured the voltage on the stay-alive while it was mounted on the decoder, and the voltage slowly drops after I turn off the power, but LED stops immediately.

Now I'm am clueless. Either I damaged LaisDCC somehow by providing stay-alive with DC turned on, or the decoder is just a piece of junk.

Does anyone have any ideas on this?

 

Edited by pygmalion
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