Led replacement bulbs for older LGB

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Portsladepete

Registered
2 Jun 2020
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Having obtained a lovely LGB post van, (with lights), I wasn’t too concerned when one bulb didn’t survive the post. Then I looked for replacement screw in bulbs!!
There are led replacement bulbs which I bought very reasonably, they fit and they work, but obviously only in one direction. I know how to make a Wheatstone bridge with diodes, but it isn’t exactly a neat solution. Does anyone know of a rectifying solution off the shelf?
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
25,878
1,461
Tamworth, Staffs.
Having obtained a lovely LGB post van, (with lights), I wasn’t too concerned when one bulb didn’t survive the post. Then I looked for replacement screw in bulbs!!
There are led replacement bulbs which I bought very reasonably, they fit and they work, but obviously only in one direction. I know how to make a Wheatstone bridge with diodes, but it isn’t exactly a neat solution. Does anyone know of a rectifying solution off the shelf?
If you have diodes 'in stock', and know how ti wire them to form a bridge rectifier then that will be cheaper, and quicker, than ordering a bridge rectifier.

Are you *sure* the lights are supposed to be on in both directions?
 
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Portsladepete

Registered
2 Jun 2020
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If you have diodes 'in stock', and know how ti wire them to form a bridge rectifier then that will be cheaper, and quicker, than ordering a bridge rectifier.

Are you *sure* the lights are supposed to be on in both directions?
In it’s pure dc state, they are on all the time when power is on, I had some large diodes (in stock) ,but it was very unsightly. The loco must have some form of power reversal, ( an older Stainz). as the lights change with direction, .
The van has an office light! An internal light! and two tail lamps. The leds look pretty good in the tail light at reasonable voltages, so ,as long as the loco is going forward they illuminate.
I have had a dcc 00 layout for a few years and had forgotten the mental gymnastics with dc, (for me that is)
 
GAP

GAP

G Scale Trains, HO Trains
14 Jun 2011
2,767
318
Bundaberg Queensland, Australia
Wheatstone bridge, there's a term I have not heard since the 1960's..... had to refresh my memory.



Small 4 terminal bridge rectifiers are cheap and available.
Thread drift on;
Wheatstone bridge used to measure an unknown electrical resistance.
Aircraft airframe people (Non Destructive Inspectors) use them to look for possible cracks in wing spars without dismantling the wings.
Thread drift off;

Possibly making a bridge rectifier is what the OP is alluding to and as Greg says they are readily available.
An example W04M - W04M 400V 1A Full Wave Bridge Rectifier
 
P

Portsladepete

Registered
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Wheatstone bridge, there's a term I have not heard since the 1960's..... had to refresh my memory.



Small 4 terminal bridge rectifiers are cheap and available.
Good old Wheatstone ,doesn’t get the credit he richly deserves, think it was a memory from school.
 
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Dan

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28 Jan 2010
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Eastern MA
You can get 1 amp diode bridges and they are small. Or make a diode bridge with 1n4001's Even though these are 25 volt ratings one needs to remember the power goes through 2 diodes so you really have 50 volt protection. Of course you could use the 1n4002 which is a higher voltage rating.
 
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Portsladepete

Registered
2 Jun 2020
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England
You can get 1 amp diode bridges and they are small. Or make a diode bridge with 1n4001's Even though these are 25 volt ratings one needs to remember the power goes through 2 diodes so you really have 50 volt protection. Of course you could use the 1n4002 which is a higher voltage rating.
in 4007 ?? Hope so, just ordered them!
 
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Portsladepete

Registered
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1N4007? Blimey! :eek::eek:

1 Amp at 1000 Volts!! - Just what track voltage do you use? :sweating::wondering:

Overkill, but you will be fine..

:rofl::rofl::rofl:
I just tap in straight from the pylons, cheaper but quite shocking at times :tearsofjoy: :tearsofjoy: :tearsofjoy:
 
stevedenver

stevedenver

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24 Oct 2009
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OP.
aside from the LED issue, and not meaning to be insulting,
The post van lamps often simply need a bit of a tightening to light again. The lamps occasionally do move enough to lose contact.
Mine "go out" from time to time, with simple running. I have only needed to tighten the lamp in the base to get lighting once again.
 
P

Portsladepete

Registered
2 Jun 2020
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OP.
aside from the LED issue, and not meaning to be insulting,
The post van lamps often simply need a bit of a tightening to light again. The lamps occasionally do move enough to lose contact.
Mine "go out" from time to time, with simple running. I have only needed to tighten the lamp in the base to get lighting once again.
No insult taken Steve, It is quite a crude but effective way of lighting compared to modern 00 stuff. I was concerned about the original bulbs going, unnecessarily as they seem to very long lived apparently. The only replacements I could find were about £20 for 10. The led bulbs were £6.99 for 10!
My Aristocraft analogue controller has their PWM system, so the original bulbs were ok at modest speeds.
I also have a start set type Piko one that struggles to provide anything over what the loco needs, so the lamps are hardly visible at those speeds. I have fitted both tail lamps, and one of the internal lamps with LEDs, also the loco headlamp.
Just for a bit of fun really, as not many steam locomotives would have a searchlight at the front etc. It is quite effective though, probably better suited to a diesel! After the novelty has worn off, I will probably return them to original.