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making my own stay-alives for HM7000TXS?


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  Does anyone know what the capacity rate of the Hornby stay-alives for the TXS decoders is?

  I plan to make my own following the guy at Strathpeffen's tutorial.  I figure that after sourcing the capacitors (10,000mf), the resistors, the diodes and the 

twin pin connectors, they work out to be about £2 each to make plus your time.

  I realise that the size of the 10k capactor will only fit old loco's and RailRoad stuff, but I have plenty of these I want to keep running and in

Jenny Kirk's latest YouTube video, she positively drools over the Hornby DMU 110, which is another old set I intend to breath new life into...

Cheers Daz  

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3 hours ago, Darren-373700 said:

  Does anyone know what the capacity rate of the Hornby stay-alives for the TXS decoders is?

  I plan to make my own following the guy at Strathpeffen's tutorial.  I figure that after sourcing the capacitors (10,000mf), the resistors, the diodes and the 

twin pin connectors, they work out to be about £2 each to make plus your time.

  I realise that the size of the 10k capactor will only fit old loco's and RailRoad stuff, but I have plenty of these I want to keep running and in

Jenny Kirk's latest YouTube video, she positively drools over the Hornby DMU 110, which is another old set I intend to breath new life into...

Cheers Daz  

This topic has already been covered on the forum several times. Whilst Strathpeffers diy stay alives are good for TTS decoders they are lacking several components that the power bank used by the TX~s decoders has. Wise advice is to not attempt to make your own even if just because you have no circuit diagram nor can you easily source the 3 pin plug.

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Posted (edited)

  Ah ok that's a shame .. but still a cheap upgrade for the couple of TTS decoders I have ... I would have thought the electronic wizardry would have been installed on the TXS decoders by Hornby already to utilise their own brand?  Does the likes of DCC Concepts and Laisdcc stay-alives mean NOT compatible also?

Cheers Daz

 

Edited by Darren-373700
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@Darren-373700 Hornby appear to have included circuitry/components in the power bank that interact with the decoder - so using an alternative is not recommended & risks damage.

It has previously been stated that the circuit diagram for the power bank is proprietary & those in possession have signed NDAs to prevent its publication.

Therefore until an electronics whizz decides to dismantle one - the only available advice has to be no there isn’t a compatible alternative.

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41 minutes ago, LTSR_NSE said:

@Darren-373700 Hornby appear to have included circuitry/components in the power bank that interact with the decoder - so using an alternative is not recommended & risks damage.

It has previously been stated that the circuit diagram for the power bank is proprietary & those in possession have signed NDAs to prevent its publication.

Therefore until an electronics whizz decides to dismantle one - the only available advice has to be no there isn’t a compatible alternative.

Back engineering the electronics is no problem but to make your own to that design requires a neat pcb to mount the bits on. A DIY version is likely to be oversize for common use.

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Asides the cost, which is not bad and you know it works, I did open a Hornby PB up and re configured its shape to allow easier fitting in a restricted space by adding fly leads to the capacitors. Easy job. 

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On 22/03/2024 at 14:38, 96RAF said:

I wouldn't give them room in my dust bin - purely personal opinion.

Actually you are so very wrong, I use these an awful lot, they are probably one of the best on the market. You obviously have never used them. Strathpeffen's tutorial explains how to make one but the thing it doesn't do is explain how to overcome the issue of when you try to program the decoder. With a simple capacitor network strung across the Vref and Ground supplies you get the issue that it takes a while for the voltage to rise when power is applied to the decoder. So in the case of a programming pulse of power the decoder can never work properly because of that huge time lag. So you need some sort of intelligence. If you analyse the Powerpack and LaisDCC "stay alives" you will see that they contain a transister/fet/triac (not sure what) and a couple of other components that basically overcome this issue. Now some people tell me that they get the simple "stay alives" to work in programming mode, how, I must admit I don't know. They have never worked for me. I did take the Hornby Powerpack apart and considering it is supposedly controlled by the decoder the circuitry didn't back that up. There again I didn't design it so I don't know. I do think though that originally they meant to use the same type as the Train O Matic ones, which would explain use of the three pin connector.

Anyway cutting to the chase, the Hornby one works ok as does the LaisDCC one. In the case of the LaisDCC ones you have to attach them between Vref and Ground rather that the 3 pin connector. Incidentally Digitrains initially guided me to LaisDCC ones as they said those and the Train O Matic ones are the ones they used all the time. The LaisDCC ones are cheaper.

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@ColinB I think the 3 pin connector thing is a red herring. It is only there to distinguish it from the 2 pin speaker connector, so they can't be interchanged. The PB is actually only 2 wires.

Edited by Brew Man
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Just now, Brew Man said:

@ColinB I think the 3 pin connector thing is a red herring. It is only there to distinguish it from the 2 pin speaker connector, so the can't be interchanged. The PB is actually only 2 wires.

I know, that is what it says in the datasheet but I suspect either they put it in, in case they needed to use the three wire device or wanted to use the three wire device but found they could get away with only using two wires. People quite often explain away their reasons for doing something, when the truth is a lot different. As I said I didn't design it so I don't know. I do know I designed a lot of electronics and software and I always added connector pins just in case I needed that signal in the future.

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The 2 pin v 3 pin plug is to differentiate between speaker port and the PB port. These size plugs don’t have the moulded ‘key’ like larger ones used in cars etc. it is to stop people not paying attend and trying to plug their PB into the speaker port etc. It’s amazing how people ignore instructions and end up causing themselves grief. 

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8 minutes ago, Rallymatt said:

The 2 pin v 3 pin plug is to differentiate between speaker port and the PB port. These size plugs don’t have the moulded ‘key’ like larger ones used in cars etc. it is to stop people not paying attend and trying to plug their PB into the speaker port etc. It’s amazing how people ignore instructions and end up causing themselves grief. 

If you do it properly (read the Train O Matic description of their product) you need one pin for ground, one pin for Vref and one pin for the charging circuit. Now you can get round this by including the charging circuit on the "stay alive" pcb which is what they have done. As I said I didn't design it but if you wanted to truly control the charging rate that is how you would do it. The LokSound decoder has a separate pin for the charging circuit. Either way that is not how the current product works. As I said when I was looking at "stay alives" I did a lot of background reading and tried out many different products.

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2 wires in a 3 pin plug was designed in purely (as stated) to stop folk plugging into the wrong socket. I believe it even points that out in the manual.

The decoder signals when (after a time lag to preclude programming in-rush problems) to enable the charging transistor on the PB. This lag allows the PB to charge when the loco is standing on track.

No simpler and no more complex than that. As stated you could do a Liais and clone your own if you are handy at direct wiring of components or can make pcbs.

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37 minutes ago, 96RAF said:

2 wires in a 3 pin plug was designed in purely (as stated) to stop folk plugging into the wrong socket. I believe it even points that out in the manual.

The decoder signals when (after a time lag to preclude programming in-rush problems) to enable the charging transistor on the PB. This lag allows the PB to charge when the loco is standing on track.

No simpler and no more complex than that. As stated you could do a Liais and clone your own if you are handy at direct wiring of components or can make pcbs.

It does and that is what I said, it is you guys that seem to be kicking up a fuss. I just pointed out the LaisDCC ones work perfectly well, which they do.

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@ColinB we have had this discussion before where you champion using the LaisDCC stay alive - with non HM7k decoders.

However since this thread is about whether anything other than the Hornby power bank is compatible with HM7k - are you saying that the LaisDCC are?

Or are you simply stating a preference that isn’t relevant to this thread?

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1 minute ago, LTSR_NSE said:

@ColinB we have had this discussion before where you champion using the LaisDCC stay alive - with non HM7k decoders.

However since this thread is about whether anything other than the Hornby power bank is compatible with HM7k - are you saying that the LaisDCC are?

Or are you simply stating a preference that isn’t relevant to this thread?

96RAF stated that LaisDCC "stay alives" were not very good which is an incorrect statement, they are in fact very good. I only use them with my Zimo decoders. With my HM7000 decoders I either use the Powerbank or in the case of P2s and 9Fs none at all. Perhaps one day when I am brave enough, I might see if a LaisDCC works with a HM7000 having looked at both circuits they look very similar. I suspect the HM7000 just uses a software switch to enable it. 

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On 22/03/2024 at 14:38, 96RAF said:

I wouldn't give them room in my dust bin - purely personal opinion.

What I said @ColinB is above. Nothing to do with quality, simply my opinion of clones.

You try what you like and I will stick with what I like.

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1 minute ago, 96RAF said:

What I said @ColinB is above. Nothing to do with quality, simply my opinion of clones.

You try what you like and I will stick with what I like.

Their decoders may be clones but in this case they are not. Now whether I haven't found the company they cloned them from, but any decent analogue electronics can design one so I am sure they can. They also make four sizes ranging from large to small, which no other company does. Zimo and YouChoos do one you can populate with your own capacitors but the circuit is missing the all important switching transistor, which means it screws up programming mode. As I said I have tried several different makes. 

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1 hour ago, ColinB said:

Their decoders may be clones but in this case they are not.
Now whether I haven't found the company they cloned them from,

They also make four sizes ranging from large to small, which no other company does.

DCC Concepts’ Zen range includes 4 sizes - might this be the company you haven’t found/heard of?

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20 minutes ago, LTSR_NSE said:

DCC Concepts’ Zen range includes 4 sizes - might this be the company you haven’t found/heard of?

No, unless they have changed the design lately. I tried them.

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The HM7000 BT IS compatible with a lot of other, and I daresay more sophisticated, stay-alives. As there's a sizeable capacitor involved, you have to provide some means of cutting the connection while programming via DCC. Sophisticated means a smaller capacitor ( usually only one or two operating @2.5..5V ) plus a step-up converter to use the capacity to its full extent. Buffering times of ~10sec under full load are not uncommon ( whether it is desirable to that extent is a matter of controversy, though ). Here's an example of how to do it

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Interesting ateshci, and everyone seems to have forgotten you posted this last year.

In summary, you’ve completely ignored that the PB is controlled for all the necessaries to allow for charging and programming via the sound profiles and you’ve put all the sophistication for this in the proprietary mini PCB made by your friend.

Is there any chance of this PCB or it’s design being available more generally?

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