Fine tuning voltage to post war accessories supplied by a fixed bus

The potentiometer should also have been rated in ohms. How many ohms was it?

Resistors limit current, not voltage.

 

You can drop AC voltage with diode pairs.  A quick search of this forum will give up many discussions on different methods of doing this.

you can use a diode dropper,shown here. Some Lionel vibrating accessories work better on pulsed half waved DC with the single diode.

 

http://www.jcstudiosinc.com/Bl...=413&categoryId=

 

the forklift may have a voltage regulating circuit,lowering voltage will not effect it maybe. You could pull it apart and maybe install a few diodes. Not sure what is in it.

 

Dale H

This kind of thread always confuses me.

 

My experience is similar to taylorra. When I insert a rheostat in series with an accessory I am able to fine tune something as the accessory will speed up or slow down as I adjust it.

 

I am not a electrical engineer so I cannot say that I reduced the voltage or that I reduced the current by inserting the rheostat. But, I can say that the rheostat did make a difference to the circuit and I got the end result that I was looking for.

 

My biggest confusion is as a layman trying to understand EE terms. I thought that if I inserted a resistance in series with a load, the current would be equal through both the new resistance and the load, but that the voltage would be proportionally divided. So if I originally have a 12V accessory connected to a 12V source that it would run at a certain speed. If I change the source to 14V and insert a proper sized rheostat that I would be able to adjust the accessory voltage to a value above or below the original 12V. In other words if I wanted the accessory to receive 11V I would adjust the rheostat so that the resistance is ohms would eat up 3V and the load would get the other 11V.

 

I hope that I have made my confusion clear and have not tried to make any one else wrong.

 

Denny

Denny, that's a pretty good explanation, and also correct.

In response to Flash's question, the pot I got at Radio Shack is labed as a 500K ohm B taper, .2 watt 20%

Thanks gunnrunnerjohn - I will no longer consider myself confused.

Denny

A 500k pot is way too high a value!  You need much lower values and much higher power handling capability.  What you have is a signal handling pot, it wouldn't pass a fraction of the current required by any accessory.

 

 

I like Dale and Rob's suggestions for using diodes for this task.

 

As Gunner said 500k is way to high. It depends on the current the accessory draws. I think a 500 ohm to 1000 ohm pot would be a better start. Probably for most accessories a 2 watt  or even 5 watt pot would be a good start. All IMO; Don