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Matt Tucker
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Discussion Starter · #1 ·
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this is hopefully not too a long shot but I am after a product developed by Chas Keeling called a voltage dropper:



Unfortunatley he has none left and is unsure if he will get any more. I was wondering whether any members had one they no longer wanted and would be willing to sell it to me

cheers

Matt
 
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A "Variac" will drop voltage . It is like a large dimmer switch. I used to use it to lower the voltage for childrens parties byt i am not sure if this works on regulated power supplies.
It's up for grabs if of use.
 

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A "voltage dropper" using diodes or resistors is a fairly easy do it yourself job for those with a little electrical knowledge.

A "Variac" is a trade name for a variable transformer, it won't work on regulated power supplies.
 

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Matt Tucker
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Discussion Starter · #6 ·
thanks guys - my electrical understanding and skills are really poor, so if I am unable to locate the CK voltage dropper do you know of anyone whom would be able to fabricate me one?

Also I note that CK also offers a 3 point choke box - would that work with resistor based controllers and used mainly with low amp drawing motors? If so what would be the main difference with the choke box and voltage dropper.

cheers
Matt
 

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Also I note that CK also offers a 3 point choke box - would that work with resistor based controllers
Yes

and used mainly with low amp drawing motors?
Yes
However, all (resistive) choke boxes will make more differance to high amp drawing motors than low amp drawing motors.
Does the box you are looking at have any more of a specification?
Subsisting higher ohmage resistors would make more differance to low amp drawing motors and probably slow down high amp motors too much.

If so what would be the main difference with the choke box and voltage dropper.
A voltage dropper would have a more similar effect on high amp drawing motors and low amp drawing motors.
A voltage dropper would have relatively more effect on top speed and less on low speed acceleration that a (resistive) choke.

The names "voltage dropper" and "choke" are applied somewhat loosely in slot racing, sometimes they are used for diodes which function somewhere between the two (usually nearer a true voltage dropper than a (resistive) choke.)
 

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Varic WILL work if you wish to use it with standard controllers and transformers, it will not work with digital these require 10 volts minimum to switch lanes.
Maybe grab the one Graham is offering
Zen
 

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A Variac will work if you plug it into the mains, and plug the track transformer into the Variac. That lets you change the power to all the lanes fed by the transformer.
I do mean transformer - like the standard home set ones. Regulated power supplies won't work this way.
 

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I dont mean to be difficult, but can somebody please explain what is meant by 'regulated power supplies', see above, I thought ALL DC transformers were regulated even variable ones.
I am a total numpty with these things and would like to know
In anticipation
Zen
 

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A regulated power supply adjusts itself so the output voltage stays the same even when the input mains voltage or output current changes.

With an unregulated supply (like the standard home set transformers) a 10% drop in the input mains voltage will result in (approximately) a 10% drop in the output voltage. So connecting a Variac and turning down the input mains voltage will reduce the output voltage.

With a regulated supply (like the ones often used at slot car clubs and as an upgrade on home tracks) it automatically adjusts itself for a drop in the input mains voltage and keeps the output the same (up to the point where the input drops too low and mostly they just switch themselves off). So connecting a Variac and turning down the input mains voltage will not reduce the output voltage.

With an unregulated supply an increase in output current (such as when two slot cars rather than 1 accelerating) the extra current will result in a drop in the output voltage. This is one of the main causes of power surges on slot car tracks.

A regulated supply automatically adjusts itself for the increase in output current so the output voltage remains the same. This eliminates one of the main causes of power surges on slot car tracks (but power surges can still happen due to wiring problems.)

I could add some detail about how accurately the regulated voltage stays constant, but I won't go into all that unless somebody is really interested.
 

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Matt Tucker
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Discussion Starter · #12 ·
Having read and researched more I am more convinced the voltage dropper product that CK offered is what I am after. So if anyone has one and wants to sell or knows someone who'd be willing to fabricate one for me then please drop me a line

thanks
Matt
 

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Hi Matt

I use a rotary switch with diodes. A diode is designed to only allow current to flow one way. however a diode will drop power by approx 0.5v so if you have a switch with 12 on it you can drop a max of about 6 volts in 0.5v steps. I made it up to drop one controller for the little girl to race with me without having to drop the whole track.

It works great, easy to do and well worth it. I have added one to my controller to drop a volt or so when i'm running slot it cars.

I can send you some pics if you fancy having a crack?

Wayne
 

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QUOTE (wayne69x @ 12 Oct 2011, 07:03) <{POST_SNAPBACK}>I use a rotary switch with diodes. A diode is designed to only allow current to flow one way. however a diode will drop power by approx 0.5v so if you have a switch with 12 on it you can drop a max of about 6 volts in 0.5v steps.
I've made a few of these and they work great.
If you want more voltage drop, just put 2 or 3 diodes (instead of just one) between the last couple of switch terminals, or more if needed.

For regular 1/32 cars, I'd go for diodes to handle 1 amp, or more.
If you are into the hotter motors, you may need to go up to 4 amps, but these get a bit bulky.
 
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