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'Keep-Alives' - Well Travelled Ground But ...
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 Posted: Sat Feb 6th, 2021 03:48 pm
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Stan S
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I know this has been discussed at length but here goes ...

There is quite a bit of info here and in other online communities,
about adding 'Keep-Alives' to Bachmann Porters with sound.

Larry Knapp, Verne Niner and others, have provided lots of help.


What I haven't been able to find,
is anyone who has connected a 'Keep-live' to a non-sound Bachmann Porter.

I found one series of posts from someone who attempted it,
then "bricked" the decoder and bailed-out.


For a whole host of reasons that don't really matter, I would like to do this,
but I have so far been unsuccessful determining the connection points.

The headlight output (function +) is easy, but the decoder common (Ground) is elusive.

I have followed Marcus Ammann's guidance,
and can measure 12V D.C. from the bridge-rectifier diodes to the function common,
but connecting the 'Keep-Alive' this way, only keeps the headlight on, not the motor.


Has anybody done this?

Stan






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 Posted: Sun Feb 7th, 2021 08:02 pm
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Helmut
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The function common (if provided) is a blue-wire (+V)
and is directly connected to the bridge-rectifier.


Addendum:

Judging from your photo, the black-wire is not connected to a proper Ground.
Take the SMD-tantalum-capacitor's (the yellow capacitor) -V tab instead.
 
It is even easier to solder there.




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 Posted: Mon Feb 8th, 2021 11:46 am
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Warren G
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The Ground is sometimes harder to find ...

You must select a point, after the bridge-rectifier, for the negative.







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 Posted: Mon Feb 8th, 2021 08:11 pm
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Si.
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" Take the SMD-tantalum-capacitor's (the yellow capacitor) -V tab "


Hi Stan  :!::brill:


BOY ! ... Those SMD capacitors are HUGE !!  :shocked:


;)


Helmuts  'Find The 0-Volts Plan'  is a good one.  :thumb:

There is very likely only one BIG polorized-capacitor, on any small PCB circuit.


The  -V  zero-Volts point on these  (most often yellow)  'solid' SMD tantalum capacitors ...

... being the UNMARKED -V end-tab  (the +V end-tab is the MARKED one on these).


The opposite way of marking, compared to an 'electrolytic' polorized-capacitor.





L:





'Common' or 'zero-Volts' or '-V' is a less confusing term than 'Ground' ...  L:

... as of course none of it is in fact 'Grounded' at all ! 


:!::cool:


Si.




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 Posted: Mon Feb 8th, 2021 09:00 pm
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Si.
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" I have followed Marcus Ammann's guidance,
and can measure 12V D.C. from the bridge-rectifier diodes to the function common,
but connecting the 'Keep-Alive' this way, only keeps the headlight on, not the motor."


Hi Stan  :wave:
Arh ... yes ... I just read this again.  :doh: :java:


The 'Stay-Alive' would need to be connected BEFORE the bridge-rectifier & capacitor.

The motors +/- polarity in 'old skool' D.C. operation, changes with loco direction.


I have never fitted a 'Stay-Alive' to anything before & know little about them. :us:


Do they have some kind of rectifier diodes of their own in there ...  ???

... to protect the 'Stay-Alive' from reversed polarity & damage ?





This is a circuit schematic for a 'DIY' stay-alive & there are NO protection rectifier diodes.  L:


:dt:


Si.




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' Mysterious Moose Mountain ' - 1:35n2 - pt.II
http://www.freerails.com/view_topic.php?id=7318&forum_id=17&page=1

' M:R:W Motor Speedway !!! ' - 1:32 Slotcar Racing Layout
http://www.slotforum.com/forums/index.php?showtopic=59295&st=0&a
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 Posted: Sat Feb 13th, 2021 02:06 pm
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Helmut
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We are talking DCC here,
where the bridge-rectifier acts as the power supply for the decoder,
which in turn governs the motor's speed AND direction.

So the 'Keep-Alive' MUST be attached to +V of the onboard bridge-rectifier,
via that resistor/diode charge/discharge arrangement,
and its minus to the -V of the bridge-rectifier.

Easiest way to do this is the tantalum capacitor's -V tab.
(seems that every decoder has one)




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 Posted: Sat Feb 20th, 2021 12:40 am
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Si.
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" We are talking DCC here,
where the bridge-rectifier acts as the power supply for the decoder,
which in turn governs the motor's speed AND direction "


Hi Helmut  :wave:


YES ! ... I know YOU are "talking DCC here" ...

... but the question is ... Is Stan ?  :us:


Cos he doesn't mention DCC anywhere ...

... just calling his loco a "non-sound Porter"


Stan will probably get back & let us know, in a few months.  ;)


I don't know $4!7 about DCC hardware ...  L:





... is that PCB hovering above Stans Porter a DCC-decoder ? ...  ???

... or is it just a Bachmann directional-lights :!: PCB ?  ???


I think I realise at any rate, you can't fit a 'Keep-Alive' to a DC loco ...  L:

... or can you ?  ???  :brill:

Anyway, Stan should be back by the Spring !  :time: :y:  :old dude:

We'll probably have figured it out by then. :!:


:java: :P  ;)


Si.




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' Mysterious Moose Mountain ' - 1:35n2 - pt.II
http://www.freerails.com/view_topic.php?id=7318&forum_id=17&page=1

' M:R:W Motor Speedway !!! ' - 1:32 Slotcar Racing Layout
http://www.slotforum.com/forums/index.php?showtopic=59295&st=0&a
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 Posted: Sun Feb 21st, 2021 03:04 pm
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Helmut
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@Si.

You bet this is a decoder :-)

Oh, it is possible for analog operation,
but may turn out to be a Rube Goldberg affair in the end:


http://www.buntbahn.de/fotos/data/8202/1900SUPERCAP.gif


And here it is working in a DC loco passing a dead spot.

Here again you can see the loco coasting,
going uphill after a supply break.




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