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I am often pleasantly surprised when the MLS Archives turn up answers to new questions I may have.

There were a couple of Lionel 0-4-0 locomotives I wanted to modify by adding a headlight and LGB smoke unit. Since current LGB locos use 5 volt circuits I wanted to try to do the same with the Lionel locos.

Remembering that someone had once recommended a Radio Shack 5 volt regulator I worked backward and first found the Radio Shack part number at http://www.radioshack.com/product/index.jsp?productId=2062599&cp

it was 276-1770. 

A search of the MLS archives for 276-1770 turned up http://archive.mylargescale.com/forum/topic.asp?TOPIC_ID=41065

and I found my answers.



[script removed] alias E.R.

1st Class Member


USA
Posted - 27 Aug 2006 :  13:15:59    [script removed]
Hi Ward,

I just got done making that circuit.

Went to Radio Shack and got the following

Full Bridge Rectifier - 276-1146
5 volt regulatgor - 276-1770
47uf Electrolytic Capactior - 272-1015
100 ohm registor - 271-1108

cost me $6.16

reason for the rectifier - allows the headlight to be on no matter which way the direction the engine is moving.

delete the use of the rectifier if you only want the light on in one direction. Since the 5 volt regular only works when + = + and - = -.


Hope that helps

Rick R.


The guy at Radio Shack could not tell me how to connect the regulator but Del had provided the information:





[script removed] Engineer

1st Class Member


USA
Posted - 27 Aug 2006 :  18:01:25  http://www.fairchildsemi.com/ds/LM/LM7805.pdf
http://www.datasheetcatalog.com/datasheets_pdf/L/M/7/8/LM78L05.shtml
The topic had been "LED Circuit Question" but that did not matter. The results were what I wanted.

Thanks to Rick and Del I now have two Lionel locomotives with lights and smoke (I like the 6 volt light I installed better than a LED). I just added a single diode to protect the 5V regulator which gives me a light in forward (only) which is what I wanted anyway.

The smoke also only works in forward but that is fine with me.

There were three main reasons why I wanted the 5 volt circuit:

1. the light reaches full intensity and stays at it quickly
2. the smoke does the same
3. I had some spare 5 volt smoke units so I did not have to buy any new ones.

Thanks Rick, Del and Shad - for making my task a LOT easier.

Jerry
 

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Hey Jerry - Your right. this place is a great resource. I am sure there are many folks that get what they need from the archives. Thanks for telling us of your success.
 

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LGB runs their smoke units on 6 volts.

You can get LM7806 regulators via mail order, lights will be bright and possibly burn out faster.

OR, just add a diode to the 5 volt regulator ground leg and get an extra .7 volts. 5.7 volts works good and you can stil have 5 volts for lights. Lights go across the ground and 5 volt output, smoke goes to the other side of the diode and output.

http://1stclass.mylargescale.com/DanPierce/LM7805_2diodes.GIF
 

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Discussion Starter #4

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A diode in series with a load will drop the voltage to the load.

In the case of my diagram, the diode on the ground leg of the regulator will raise the voltage if you tie one bulb lead to the minus side of the diode bridge and the other lead to the output lead of the regulator.

Some diodes drop .7 volts, others do .3 volts. Always verify with a meter after building the circuit.

In my diagram, you could use the LM7806 regulator and add a single diode that drops .3 volts and this is what you may have done.

Take a picture of your circuit so i can see how you hooked up the diode.
 

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Discussion Starter #6
Hi Dan,

I've reassembled the locos so a photo would mean disassembling on of them.

What I did is pretty simple.

1. I used the center of the regulator as a common ground to the negative from the drivers (track) and also to one side of the light and smoke units.

2. The input of the regulator was connected to the bar side of the diode. the blank side of the diode was then connected to the positive from the drivers (track). 

3. The output of the regulator was connected to the other leads to the light and smoke unit.

Both the smoke unit and the light are wired the same.

I get mixed up on the positive and negative of the diodes so I simply use an ammeter to tell me when I have it hooked up right. Then the light coming on in forward confirms it.

In addition I connected a LGB wiring harness (from their 68333 light) through the back of the tender to MU with a trailing sound car but that was simply connected to the driver wires and is not part of the 6 volt circuit.

Jerry


Posted By Dan Pierce on 03/20/2008 5:27 AM

Take a picture of your circuit so i can see how you hooked up the diode.
 

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A diode conducts when the BAR end is negative.
 

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Jerry, I fully understand how you hooked up the regulator.

Reason for 6.4 volts could be a meter reads the possible oscillations from not using a .1uf capacitor on the input and output of the regulator.

Your diode protects the regulator from having reversed voltage input. I use a diode bridge so reversing track power still allows my regulator to function.
 
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