limiting train full throttle speed??

[Blizz]

I want to cut down the o/p voltage of my transformer by 2-3 volts to slow the train down but yet enabling my grandson to use the full throw of the throttle..    What can I use to accomplish this..  I tried a resister and it worked but  prevented the horn/whistle from operating.   Would really like to have the whistle function and keep the train on the track..   Was thinking of trying a house dimmer inline with the output line to the track..    Any help would be appreciated.   This application is for a O gauge setup steam engine using a Lionel CW-80 transformer.

Thanks in advance

Blizz

[TrainLarry]

An easy solution is to use a variable isolation transformer. It would allow you to set the output voltage to any value you choose.

 

Larry

[Blizz]

Thanks Larry..  Is that in place of my Lionel transformer??

Blizz

[ADCX Rob]

Check THIS LINK for a discussion on this.

lionelsoni

... the best voltage-dropping element that I know is a string of silicon diode pairs.  They will give you a constant voltage.  The simplest way to do this is with one or a few bridge-rectifier modules:  http://www.radioshack.com/product/index.jsp?productId=2062583  Connect the + and - terminals together.  Then use the ~ terminals to wire the module in series with your transformer.  You can use the +- junction as an intermediate tap.  If you need lower voltage, just add another module in series.

 

[lionelsoni]

Rob, I started to suggest that, but I hesitated because he says he's using a CW-80, which makes the DC voltage component to blow the whistle by differentially offsetting the turn-on times in the positive and negative half-cycles of the waveform.  Reducing the waveform voltage, whether with diodes or the resistor that he tried, will also reduce the DC voltage component that the offset causes.  The diode scheme does this by subtraction of voltage instead of multiplication, which might make it marginally different; but I am not optimistic about it.  The same consideration applies to lowering the line voltage supplying the CW-80.

Traditional Lionel transformers avoided this problem by switching in the separate 5-volt whistle winding.

I don't have a CW-80 to experiment with; but I wonder whether simply offsetting the handle on the speed potentiometer would be hard to do.  Perhaps someone familiar with that can post some advice. 

[8ntruck]

I've got diode strings in the downhill block of my layout powered by a CW80.  With a Railsounds tender, the whistle and bell still work.  A tender from circa 2005 with a motor type whistle works on this set up as well.

I have not tried any post war relay type whstles.

Good Luck.

[bobhwalker]

Although there are a number of ways to control maximum speed, one of the great advantages of bluetooth based app enabled speed control is that maximum speed can easily be set for each individual loco. Also, the reaction to throttle changes can be adjusted on both speed increases and decreases. Very useful for keeping things under control.

[Blizz]

Don't know whats needed to accomplish that bluetooth setup but it's probably too late to do it for Christmas..

Thanks for you input.

Blizz