How do I make a simple power buffer for coach lighting.

stockers

stockers

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I am thinking of using a single set of pick up wheels (because they are expensive) to run some carriage lights - LEDs. If I add a capacitor it could run the lights whilst the wheels are not picking up for any reason.
It cant be that simple, can it?
I assume I need some form of voltage limiter feeding from the capacitor to the LEDs, and what about over supply to the capacitor.
Can anyone come up with a seriously simple design - a bit crude is OK - its only a few LEDs after all.
 
stockers

stockers

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Thanks - parts ordered on ebay. Multiple quantities will be cheaper - i just spent about £6 to make one.
 
Slawman

Slawman

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I am doing that now by just putting a capacitor (whatever size you need depending on your lights) across the output terminals of your regulator. You don't even need to solder it if your converter has screw terminals already. ie:

https://www.ebay.com.au/itm/LM7812-DC-AC-Three-terminal-Voltage-Regulator-Module-15V-24V-to-12V-1-2A/183164014089?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Plus 1000uF cap:

https://www.ebay.com.au/itm/5-x-25V-1000UF-105C-Radial-Electrolytic-Capacitor-10x20mm-G5M2/183032835297?epid=1969065735&hash=item2a9d9b6ce1:g:tzwAAOSwn9VaZwUU

Equals flicker free lighting.

This wont hold the lighting up for any period of time, just enough time to stop them dropping as the carriage makes intermittent electrical contact while moving along your track.
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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Hi John,
Value, and source of 'Super-Caps' please?

TIA,
PhilP.
 
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Slawman

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Slawman

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I agree it is worth clarifying which side you are planning on attaching. I am using 25v now with no problem. My system peaks at 22v.

Do you recommend attaching the Cap to the output side?
 
stockers

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I like the board with rectifier built in. using 35V cap here.
 
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stockers

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Thanks for that John.
 
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stockers

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That is exactly what I was on about - simples.
Thanks.
 
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Slawman

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That looks a neat unit John. How are your terminal blocks mounted? I can only find ones you must solder into the board. What size cap is that?
 
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Last edited:
Bill Barnwell

Bill Barnwell

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I am thinking of using a single set of pick up wheels (because they are expensive) to run some carriage lights - LEDs. If I add a capacitor it could run the lights whilst the wheels are not picking up for any reason.
It cant be that simple, can it?
I assume I need some form of voltage limiter feeding from the capacitor to the LEDs, and what about over supply to the capacitor.
Can anyone come up with a seriously simple design - a bit crude is OK - its only a few LEDs after all.
Well I would like to recommend battery powered LED's. I used 10mm soft white , was able to mount them in the factory location , hid the batteries(2AAA) and RC car switch in the clearstory. Used stained glass copper foil tape to make connections so that there were no wires hanging down. Accidently left on for 3 weeks and were still lit when found.
No flicker and stay lit when in station, Bill
 
stockers

stockers

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Thanks Bill but I dont want the hassle of batteries. I have several coaches already running with bulbs but am sorting out a simple way of using LEDs with minimal pick ups. With over twenty coaches, the recharging would drive me nuts. Have loads of power in the rails already.
Stick coach on rail - lights work, 'Simples' as the meercat would say.
 
stockers

stockers

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Well, it works. My strip of LEDs has an inbuilt resistor to be fed at 12 V. At this output the capacitor lasts about a second - not really long enough. The advice above indicates using bare LEDs at 3V which should result in a much longer supply from the cap. I need to go collect my plain LEDs which are at the Kent &East Sussex Railways model railway.