# Making a bridge rectifier



## infernisdiem (Nov 12, 2011)

ok, I know that I posted something like this before, but I have come across some what I believe are diodes, and I was wondering if anyone has had success in making a bridge rectifier from scratch. I have found a couple of diagrams online and have tried to replicate them, but have had no success in making my Lionel 8902 DC powered train run off from my Lionel AC transformer. 

This is one of the sites that I found, and based my design off from:
http://www.instructables.com/id/AC-to-DC-converterdiode-bridge/?ALLSTEPS


----------



## infernisdiem (Nov 12, 2011)

Thought that just crossed my mind, is there a way to take a Marx 1666 motor set up and mount it into the lionel 8902 body?


----------



## Kwikster (Feb 22, 2012)

I know it can be done, but it will lock you into only one direction with no reverse. Lionel does have a part list here: http://www.lionel.com/ForTheHobbyist/GeneralTipsAndFAQs/TechTip2.cfm that converts a d/c to a/c while retaining reverse via and electronic reverse unit.

Carl


----------



## infernisdiem (Nov 12, 2011)

Kwikster said:


> I know it can be done, but it will lock you into only one direction with no reverse. Lionel does have a part list here: http://www.lionel.com/ForTheHobbyist/GeneralTipsAndFAQs/TechTip2.cfm that converts a d/c to a/c while retaining reverse via and electronic reverse unit.
> 
> Carl


I know, but I am not to worried about it going in two directions at the moment, the lionel electric E unit is a bit to expensive for this rail roader at the moment, at least that is what the wife says until we get a new place :laugh:


----------



## Dave Sams (Nov 24, 2010)

If you aren't sure what you have, I'd suggest buying a rectifier at Radio Shack. Get the largest one they have. 

You may have to use a heat sink as well. 

I have several on my layout.


----------



## T-Man (May 16, 2008)

Make a bridge. Sure. 











For engine running you need 8 amp diodes at a minimum. The ones shown are small switching diodes. I had heat problems with a scout motor and gave up.

A reverse unit is 15 bucks and worth it. You could look at my powersupply and convert the transformer to 12 volts DC. The cost is the same or more. Mine is only 4 amps I do not know if it is enough to run a Lionel DC motor.


----------



## gunrunnerjohn (Nov 10, 2010)

A bridge rectifier is simply four diodes, there's no magic in creating one.

Connect them like this, the line on the diagram is the band on the diode. 

*+* and *-* go to the motor, and the *~* leads go to the track pickup and wheels.


----------



## T-Man (May 16, 2008)

Buy any small HO transformer rated a 7volt amps DC. They get as cheep as a buck. Lionel has a version of these too. I have one .I have one DC transformer on my layout to work with a Reverse board I made.


----------



## infernisdiem (Nov 12, 2011)

where do you find the HO transformers at?


----------



## gunrunnerjohn (Nov 10, 2010)

Tons of them on eBay. I have a couple here in a box somewhere.


----------



## infernisdiem (Nov 12, 2011)

I have a few ho scale transformers as well, but it doesn't seem to have enough umph to run it off track, I'll see if I can find my other two, maybe one of them will work


----------



## BigAl56 (Dec 14, 2011)

You can pick up bridge rectifiers for cheap at Digikey.com or Radio Shack. Watch out for the wattage. A locomotive draws far too much power for a typical 1/2 watt diode you have. They will fry in seconds. 

Bridge rectifiers are great to quiet the buzzing sound some accessories make. I use them for crossing gates and semaphores. You can also use them to quiet the buzz of an e-unit.


----------



## T-Man (May 16, 2008)

I tested a mantua transformer and ran my 8402 DC off the track at 7VA.


----------



## infernisdiem (Nov 12, 2011)

I had one that was handy, but apparently it isn't working, so after digging through all of my HO track and trains, I found two more, one by tyco that works, and a no-name one that at 40% moves my train at a good clip, any higher and it flies off the track. I have to say that this 2-4-0 runs great for a train that hasn't been run in a long while.


----------

