Doubling Up Stay Alives

[brossard]

I've done a couple of quick searches on Google and here, but nothing leaps out.

 

It occurs to me that putting two stay alives on a decoder might offer benefits.  Anyone done this?  How is it wired?

 

I sense eyes rolling but humor me.

 

John

[nick_bastable]

series may  work parallel will half the effect why not just add extra capacitors ?

juxtaposed my reply apologies

 

Edited September 21, 2023 by nick_bastable
been a idiot

[brossard]

1 hour ago, nick_bastable said:

series may  work parallel will half the effect why not just add extra capacitors ?

 

I have two stay alives, one with a fried decoder and the other with the new decoder.    I guess I can daisy chain them.  I want to make sure there's enough capacitance to keep the vehicle going (Heljan 4 wheeled AC Railbus in 0).  I don't get the last part of your comment.

 

Anyway, thanks for commenting.

 

John

Edited September 21, 2023 by brossard

[Nigelcliffe]

Which stay-alives,  and which decoders ?   

 

In general, just increase the capacitors,  there's no need for "two control circuits".   

Which in turn may be "select the right capacitor chemistry".   

 

But, I wonder why you think you need "two".   If a decent stay-alive will give 0.5 seconds of run-on (and many are much much more than this), and you've lost power for 0.5 seconds, then you've a track problem.   

 

 

Note that quite a lot of "gold caps" /  "supercaps" you'll find on sale from electronics sources are not suitable for stay-alives;  they can store a lot of power, but only release it very slowly (eg. to keep a small microprocessor running for hours), rather than release power rapidly for running a motor.    One needs to know what you're looking at in specification sheets.  

 

 

[BroadLeaves]

11 hours ago, nick_bastable said:

series may  work parallel will half the effect  ?

It's the other way round. Two or more capacitors in parallel gives you a total capacitance of the sum of the individual capacitances, but two or more in series less than any of them on their own. Specifically, for series connected, the total capacitance is the reciprocal of the sum of the reciprocals of the individual capacitances.

[Nigelcliffe]

1 minute ago, BroadLeaves said:

It's the other way round. Two or more capacitors in parallel gives you a total capacitance of the sum of the individual capacitances, but two or more in series less than any of them on their own. Specifically, for series connected, the total capacitance is the reciprocal of the sum of the reciprocals of the individual capacitances.

 

Correct for capacitors. 

 

Connecting two stay-alive modules in series is likely to be "interesting", but probably not "blue smoke".   

[brossard]

4 hours ago, Nigelcliffe said:

Which stay-alives,  and which decoders ?   

 

In general, just increase the capacitors,  there's no need for "two control circuits".   

Which in turn may be "select the right capacitor chemistry".   

 

But, I wonder why you think you need "two".   If a decent stay-alive will give 0.5 seconds of run-on (and many are much much more than this), and you've lost power for 0.5 seconds, then you've a track problem.   

 

 

Note that quite a lot of "gold caps" /  "supercaps" you'll find on sale from electronics sources are not suitable for stay-alives;  they can store a lot of power, but only release it very slowly (eg. to keep a small microprocessor running for hours), rather than release power rapidly for running a motor.    One needs to know what you're looking at in specification sheets.  

 

 

 

Decoder is easy, Zimo MS440C.  It comes with a stay alive unit.  The stay alive that was attached to the fried decoder is DCC Concepts.

 

Here's a lousy pic:

 

The stay alive in the packet is labelled 1000 micro Farad.  (I like that the wires are pre-soldered, I never like having a soldering iron near a decoder). The other one has no indication of its value.

 

I do remember that the railbus would stall from time with it's old stay alive so think more capacitance might be the answer.  I don't have a feel for what the capacitance should be.

 

However, I've never seen doubling up on stay alives discussed before, perhaps it's taboo.

 

So, can I wire the two together?  Would that be in parallel, as mentioned above?

 

John

 

 

 

[Kaput]

2 hours ago, brossard said:

However, I've never seen doubling up on stay alives discussed before, perhaps it's taboo.

 

Think its less taboo and more just not really got any point.

 

If the stay alive isn't enough for reliable running then its either fix the track issue (ideal solution but not always possible) or put a bigger stay alive on. The LaisDCC stay alives can keep the average OO locomotive running without track power for far longer than is generally considered a safe idea.

[Nigelcliffe]

4 hours ago, brossard said:

 

Decoder is easy, Zimo MS440C.  It comes with a stay alive unit.  The stay alive that was attached to the fried decoder is DCC Concepts.

 

......................

 

 

The stay alive in the packet is labelled 1000 micro Farad.  (I like that the wires are pre-soldered, I never like having a soldering iron near a decoder). The other one has no indication of its value.

 

I do remember that the railbus would stall from time with it's old stay alive so think more capacitance might be the answer.  I don't have a feel for what the capacitance should be.

 

However, I've never seen doubling up on stay alives discussed before, perhaps it's taboo.

 

So, can I wire the two together?  Would that be in parallel, as mentioned above?

 

 

I would NOT try attaching the DCC-Concepts device to the decoder you have.    The decoder already has the capacitor management circuits built in, and is expecting just capacitors to be added to it.  

 

I would recommend following the Zimo manual.    

 

In that, the MS440C can accept unlimited capacitors that are at least 15v rated on the output.   The manual shows several options, including a block of six "gold caps" rated at 50,000uF.     
YouChoos are probably the easiest to follow for this sort of thing of the DCC retailers I've checked, they have six gold-caps unwired for £10 (0.3F as six in series = 50,000uF), or £12.50 (150,000uF, physically larger capacitors), or Zimo-badged and wired together for £20.    Alternatively, you can buy a capacitors which are >15v rated in various shapes/sizes, eg. YouChoos have a "flat brick" of 6800uF.      
If there's space, I'd fit the six smaller gold caps (0.3F each, 50,000uF when in series).   

 

 

"Too much" isn't an issue with a Zimo decoder.   If you find you have too much energy stored (so the loco can do a comedy run across the bench), then there's a CV in the decoder to say how many tenths-of-second the loco should run before it decides there is no DCC signal and stop the motor.     

There's an advantage to "lots of stored energy" in a Zimo decoder - should the loco come to a stop on a piece of dirt, it will attempt to move forwards off the dirt to find track voltage (I don't know of any other decoder which tries to do this, and with a big enough capacitor you can see it doing it).   This requires lots of energy as a motor which is stationary needs quite a shove to make it move.   

 

 

[brossard]

32 minutes ago, Nigelcliffe said:

 

I would NOT try attaching the DCC-Concepts device to the decoder you have.    The decoder already has the capacitor management circuits built in, and is expecting just capacitors to be added to it.  

 

I would recommend following the Zimo manual.    

 

In that, the MS440C can accept unlimited capacitors that are at least 15v rated on the output.   The manual shows several options, including a block of six "gold caps" rated at 50,000uF.     
YouChoos are probably the easiest to follow for this sort of thing of the DCC retailers I've checked, they have six gold-caps unwired for £10 (0.3F as six in series = 50,000uF), or £12.50 (150,000uF, physically larger capacitors), or Zimo-badged and wired together for £20.    Alternatively, you can buy a capacitors which are >15v rated in various shapes/sizes, eg. YouChoos have a "flat brick" of 6800uF.      
If there's space, I'd fit the six smaller gold caps (0.3F each, 50,000uF when in series).   

 

 

"Too much" isn't an issue with a Zimo decoder.   If you find you have too much energy stored (so the loco can do a comedy run across the bench), then there's a CV in the decoder to say how many tenths-of-second the loco should run before it decides there is no DCC signal and stop the motor.     

There's an advantage to "lots of stored energy" in a Zimo decoder - should the loco come to a stop on a piece of dirt, it will attempt to move forwards off the dirt to find track voltage (I don't know of any other decoder which tries to do this, and with a big enough capacitor you can see it doing it).   This requires lots of energy as a motor which is stationary needs quite a shove to make it move.   

 

 

 

Now that is very useful information Nigel.  What I think I am reading is that the so called stay alive with my decoder is nothing more than a bog standard capacitor.  I thought that the stay alive had some clever circuitry but that's in the decoder.  So, I should be able to go to an electronics store and buy these, I might even have some, must do a rummage.  I suppose that's what others above were trying to tell me.

 

Message received about the DCC Concepts SA.

 

I added a DCC Concepts SA to my Dapol Sentinel which has an earlier Zimo decoder, MX644 I think.  The loco runs well but after this I'm thinking I should put a simple capacitor in.

 

Many thanks everyone.  Isn't education wonderful?

 

John

Edited September 21, 2023 by brossard

[Nigelcliffe]

3 minutes ago, brossard said:

 

Now that is very useful information Nigel.  What I think I am reading is that the so called stay alive with my decoder is nothing more than a bog standard capacitor.  I thought that the stay alive had some clever circuitry but that's in the decoder.  So, I should be able to go to an electronics store and buy these, I might even have some, must do a rummage.  I suppose that's what others above were trying to tell me.

 

Whether you can find suitable capacitors in a local electronics store depends on the store.   
Not all super-caps (things in the 100,000uF and above region) will be suitable,  many are designed for low current use (so won't work), some are designed for higher current applications.  

 

 

The "clever circuitry" can be little more than a resistor and a diode;  resistor to limit charging current to the capacitor (otherwise the charging in a mili-second would overload and shutdown a DCC system) and the diode to allow maximum outbound current when required.       
But, it can be considerably more complex than that,  Zimo's system on the MS440 allows the use of 15v rated capacitors, yet the decoder is safe on track at well over 20volts,  so the Zimo is regulating the voltage at the capacitor.   

 

 

5 minutes ago, brossard said:

 

I added a DCC Concepts SA to my Dapol Sentinel which has an earlier Zimo decoder, MX644 I think.  The loco runs well but after this I'm thinking I should put a simple capacitor in.

 

 

A different decoder, which will have a different manual to consult.....      And has two different ways to connect a stay-alive.     What applies to one decoder design does not apply to another one.    

 

 

 

[peterm1]

I'd go with the Lais stay alive for simplicity. I use them as belt and braces. I adjust CV153 to 20 tenths of a second and CV111 to 1 so that the loco stops dead after 2 seconds, rather than going to CV4 deceleration.

[brossard]

I've been talking to YouChoos about their 6x Mini Caps with 0.3F of capacitance.  Good thing I did because I also need a "Life Link" board.  I expect I'll order these for both the Railbus and Sentinel.

 

John

[Michael Hodgson]

Some stay-alives have their own control circuitry built in.

Some decoders have stay-alive control circuitry and you just need to add the capacitors.

 

I've seen pretty impressive demos of a loco being taken off the rails and running on bare baseboard.

Great trick, but how long do you really want your loco to continue running if it happens to have left the rails?

[brossard]

I'm a complete newb when it comes to stay alives, so this thread has been an education.

 

I gather that ZIMO MX644 and MS440 decoders have control circuitry already, so I just need to add capacitors.  How much capacitance?  Well, frankly I don't know.  I suspect the 1000 micro Farad cap supplied with the decoder is way too wimbly, which is where my original question stemmed from.

 

We were talking about this yesterday when the lads came round.  My layout is no problem since there are no precipitous drops.  However, if you have a lift up section and rely on a section of dead track before the gap, a loco with excessive stay alive may defeat that and plunge to it's demise.

 

John

[Free At Last]

I only have the 'stay alives' as supplied with Zimo MX644 and MX645 decoders.

I would be happy if they just kept the sound going when the polarity changes on my Heljan turntable.

[Michael Hodgson]

9 minutes ago, Free At Last said:

I only have the 'stay alives' as supplied with Zimo MX644 and MX645 decoders.

I would be happy if they just kept the sound going when the polarity changes on my Heljan turntable.

Your turntable has flange squeal?

[brossard]

47 minutes ago, Free At Last said:

I only have the 'stay alives' as supplied with Zimo MX644 and MX645 decoders.

I would be happy if they just kept the sound going when the polarity changes on my Heljan turntable.

 

I'm curious, do you find the, as supplied, 1000 micro farad caps effective?  I am skeptical hence this thread.

 

John

[Free At Last]

1 hour ago, brossard said:

 

I'm curious, do you find the, as supplied, 1000 micro farad caps effective?  I am skeptical hence this thread.

 

John

No, what I was trying to say is that they don't even keep the loco sound going for the split second the turntable goes over the polarity change gap, and that if they did then I would be happy with just that. I don't see their purpose, they behave no different to the locos I have that don't have 'stay alives'. 

Edited September 23, 2023 by Free At Last

[brossard]

58 minutes ago, Free At Last said:

No, what I was trying to say is that they don't even keep the loco sound going for the split second the turntable goes over the polarity change gap, and that if they did then I would be happy with just that. I don't see their purpose, they behave no different to the locos I have that don't have 'stay alives'. 

 

Depends on the loco I think.  The two I've been going on about are 4 wheeled and, in my experience, these are prone to stalling.  I have never met track that is perfectly laid.  My others, 6 coupled and diesels, are fine.  Even my latest Dapol B4 is excellent despite being 4 coupled, because it has factory compensation.

 

So, I sort of agree with you and I'm doing stay alive on a case by case basis.

 

John

[Nigelcliffe]

4 hours ago, brossard said:

I've been talking to YouChoos about their 6x Mini Caps with 0.3F of capacitance.  Good thing I did because I also need a "Life Link" board.  I expect I'll order these for both the Railbus and Sentinel.

 

 

Don't need the Life Link board for the MS440 decoder.    Read the Zimo manual for MS/MN decoders, it shows precisely the arrangement you are proposing to fit: six 2.7v capacitors in series onto the two wires.

Life Link board connects to different wires to the two you have emerging from the side of the MS440.   It will work, but is different. 

 

MX decoders are a different matter.  Again, read the Zimo manual for MX decoders.

 

 

- Nigel

 

[brossard]

1 hour ago, Nigelcliffe said:

 

Don't need the Life Link board for the MS440 decoder.    Read the Zimo manual for MS/MN decoders, it shows precisely the arrangement you are proposing to fit: six 2.7v capacitors in series onto the two wires.

Life Link board connects to different wires to the two you have emerging from the side of the MS440.   It will work, but is different. 

 

MX decoders are a different matter.  Again, read the Zimo manual for MX decoders.

 

 

- Nigel

 

 

Right Nigel, not for the MS440 but I also bought a 6x stay alive for the Sentinel which has the MX644 and that does need the Life Link.  Easier to ask YouChoos, a lot of words in the manual.

 

Cheers

 

John

 

BTW, shout out to YouChoos.  They have answered my questions promptly.  My order will be in the post on Monday.

 

Edited September 23, 2023 by brossard

[Free At Last]

1 hour ago, brossard said:

 

 The two I've been going on about are 4 wheeled and, in my experience, these are prone to stalling.  I have never met track that is perfectly laid. 

I have an old Hornby pug that never falters, I'm not saying my track is perfectly laid but the use of a graphite stick has done away with the need for 'stay alive' for running purposes.

[Sir TophamHatt]

On 21/09/2023 at 09:42, Nigelcliffe said:

But, I wonder why you think you need "two".   If a decent stay-alive will give 0.5 seconds of run-on (and many are much much more than this), and you've lost power for 0.5 seconds, then you've a track problem.   

If it's a means to an end though?

 

If you develop a track problem, I'd rather have a stay-alive of 10 seconds than half a second if it means I don't have to rip up half the layout :P

 

0.5 seconds is barely worth it IMO but then I see the advantages of much longer stay alive times more than disadvantages.

[brossard]

25 minutes ago, Sir TophamHatt said:

If it's a means to an end though?

 

If you develop a track problem, I'd rather have a stay-alive of 10 seconds than half a second if it means I don't have to rip up half the layout :P

 

0.5 seconds is barely worth it IMO but then I see the advantages of much longer stay alive times more than disadvantages.

 

Well, yes, intuitively I think more is better in this case.  I really don't think you can rely on track being straight, flat and true.  Dirt comes into the equation as well.  Loco compensation, or even springing, helps.  It is very frustrating to have a loco stop, especially one fitted for sound.

 

So, stay alives are winging their way across the briny and we'll see what we get.  I shall report on my observations.

 

Obviously, coming into this thread I was totally clued out about stay alives and I (others too I hope) have been educated.  From that point of view this thread has been worthwhile.

 

John