How to lower track power for grain of wheat bulb for the drumhead

Using a diode will cut the ac voltage by half

Why bother with a grain of wheat bulb that will eventually burn out? Just put in an LED.

Hello Matt.........

 

Interesting, How do I hook up right using the Diode ? Can you make a wiring drawing of that and what brand and model of Diode should I use ?

 

Tiffany

Hello Chris...........

 

I would have used the LED but no one makes a kit for that (single LED and 2 wires hook up)

 

Tiffany

Tiffany,  check with Roy

 

http://www.royztrains.com

 

Try Evan Design .  They have everything.      

 

 

http://www.modeltrainsoftware.com/ledlights1.html

Hi Tiffany,

Go to Tomar Industries,they sell drum head kits and the diode size may be listed or contact me and I will photo the Tomar  instruction sheet and send them to you.

Mikey

You can also call Tomar Industries and speak to Duane who can tell you what size resistor to use.  I asked that question myself because I wanted to eliminate the ballast bulb and rectifier chain that they used long ago.  IIRC, Duane said to use a 220 ohm resistor. 

 

Mikey, about a month ago I burned out the incandescent bulb in an older, pre-LED Tomar drumhead, and bought an LED replacement kit from TI.  It included a full bridge rectifier and resistor, along with a tiny, pre-wired LED.  Glad to report the installation went well.

 

 

The other issue if one uses the gow bulb is the heat it will generate in this confined space. The heat will eventually brittle the plastic in the long term. Do it right the first time and use the chip led to light up the drumhead. Evans designs will take care of you.

Add another 14v bulb in series with the drumhead one, it will cut the voltage in half for both. Just put the added bulb somewhere in the car. easy and very inexpensive.

Second the Tomar Industries.  The kit includes a very small LED and the dropping resistor. 

 

The kit also includes a bridge rectifier to convert AC to DC along with the dropping resistor.

Bridge rectifier.

Note how small the LED is. Red and Blue wires.  Bottom of picture next to the keystone.

 

 

Evan designs make a 2 wire LED that is a drop in replacement for the grain of wheat...

 

Marty

Hello Marty..............

 

Do you have the picture of that ?

 

Tiffany

I'm not Marty but I have used the LEDs he refers to. They are shown on the Evan Designs webite here:

 

http://www.modeltrainsoftware.com/bl-212.html

 

and (best of all) they are indeed a simple drop-in LED bulb replacement for the GOW bulb. You probably want the medium size of the three shown; these lights are VERY bright.

Hello Hancock52.............

 

Thank you !!! is the 3mm size the right size for the drumhead that's about 1/2 inch inside dia. What is that black square thing in the middle between the wires ? I wondered how to get it through the drumhead then small hole that I drilled on bottom of the back door then to the back ? see picture guys

 

Tiffany

Tiffany, if you scroll down the page of the link Hancock52 supplied you'll find a tab titled "LED Installation Tips."  You can probably find the answer to your installation questions.  And click on the "rectifier unit" link to answer your question about the "black square thing."

 

 

 

 

 

  This is early Tomar.

 

Bill

In some of the threads regarding LED lighting, are links to voltage regulators, dirt cheap from China.  Output voltage is adjustable, and they work just as well with incandescent as LEDs.  You can set it at the desired voltage, and it will never get higher, nor get dimmer unless you cut inpit voltage below the setting.

 

In those threads, you can also find "home-built" equivalents.  I believe Gunrunner John markets one through Hennings Trains.

I would convert all the cars to LED lighting. Is anything in the drumhead now? You also may want to series wire your engines or install a voltage dropper.

 

Dale H

Hello Dale H........

 

There is a grain of wheat bulb in the drumhead but its not hook up yet.

 

Tiffany

 If you have a spot to use the bulb elsewhere & don't mind the money, and extra efforts go led.

 But the resistor should work for pennies. You have a bulb. And the lower brightness means less heat effect if you mount it in the car vs drumhead.

 The led can produce a more localized spot of light on the drumhead than a bulb does too. Choose the widest focus you can find. I've faced leds backwards to use only reflected light too, but that produces a dark spot most often.

 

 Staying with the bulbs, and not the cheapest option, but is more of a future led friendly set up, a few diodes, bridge rectifier, two capacitors, and a 7809 voltage regulator would give nice steady power that would also continue for a few seconds uninterrupted at power losses (seconds? decided by choice of "bulb side" cap).(google for 7809 diagrams, they are common) Its rating is up to 24 volts if I remember right, but about 15v is best for longevity so with command at 18v, I'd add a diode or two so the power enters at it about 15v. I think 1.5 amp or maybe a touch more was ok for steady current flow. If you research it more one quick look at a spec sheet would answer doubts as to exact variances.

Lots of ways to do it, what's best for you depends on your tastes. I like bulbs.

Just put a diode on the Hot leg of AC current. it will cut off the negative voltage drop on the AC thus reducing the voltage potential by 1/2

I think that the black square component is mainly the bridge rectifier to convert AC track current to DC. Not sure where the resistor and any other components are. But in any case the beauty of these things - apart from the fact that they are guaranteed to work and do - is that you don't have to construct your own power feed or worry about which of the lead wires goes to hot and ground. You literally just wire it in in place of the GOW bulb.

 

I recommend opting for their warm white version. 3 mm will be OK if you want the drumhead to be bright but the 1.8 mm one would most likely work as well. I think you would just put the bulb in the drumhead and conceal the rest of the wiring elsewhere.

 

Only downside is that these are small components and therefore slightly fiddly to work with but otherwise they are great.

If you want to keep the bulbs,the easiest way is to get a 3 or 4 amp bridge rectifier. Connect the + and - together and put the remaining 2 leads marked ~ in series with either lead of the light bulbs for general lighting in the car. This will drop car lighting by only 1.4 volts. The tapping those same 2 leads you will have a constant 1.4 volts when current is pulled through the rectifier. . Wire a 1.8 or 3 volt or 6 volt grain on wheat bulb to it. It will burn at constant intensity regardless of throttle setting.

 

Dale H

hello Hancock52 and Dale H, guys

 

I wanted to install LED type bayonet base bulbs and use the factory light sockets. LED

small size for the drumhead will do the trick?  The cars are Lionel 15 inch aluminum 

passenger cars being pulled by Williams F-3's.

 

Tiffany 

The LED bayonet are rated at 12 VDC. You are running up to 18 VAC on the layout. They will dim the same way the light bulbs do. You could put an LED in the drum head. Install the bridge rectifier conventionally with the 2 AC track leads to the bridge AC leads, then + and - to the LEDs to get DC,then use a single diode string dropper, 4 or 5 in4001 diodes in proper polarity and in series from 1 of the polarized leads. . . That will drop a bit less than 3 volts with 4 diodes or 3.5 volts for 5 diodes. and reduce voltage to the bayonet LEDs.  Use that clamped around 3 volts voltage from the ends of single diode string for the LED in the drum head. There should be enough voltage to drive it with an 18 ohm resistor in series. 

 

Dropping voltage with diodes is explained here

 

LINK

 

Dale H