slot car power supply
Hi there Lejoy.
What you have there looks like a contender for a good slot car power supply.
Not sure what the red button is, reset or something like that, or charge start ?.
Any way the easiest way is to modify your psu for the job.
I very much doubt the full exciting circuit can be modded for 0 - 14 volts DC.
You could keep the bridge rectifier, and maybe use the filter capacitors, although motors of the permanent magnet type are not fussy on some out put ripple.
I would use a regulator circuit to power the cars, most wont go down to 0 volts DC , but they will drop to 2.5 volts or less, this wont move a 12 volt DC slot car, so is as good as 0 volts DC, when not powered the supply would be loaded at 2.5 volts or less, but the small motor windings will only draw a modest current, this is fine on the supply and the cars, until you turn up the voltage and power up the cars.
For control i would opt for a slider potentiometer as opposed to a rotary one, it would be more practical, although either will work.
A voltage regulator circuit can be found on the web, there are many, some easy some more complex depending on the final use, if it where me i would build a small circuit on copper strip board and mount inside the box unit.
Really i doubt the existing circuit will ever take you to 0 volts and back up to 14 volts.
there is a kit available from transformer to out put posts circuit, its relatively cheap, but only supplys 1 amp, you can replace the diodes for the rectifier with larger current ones, and use a 5 amp IC regulator in place of the kit one.
I will list the parts to replace in the kit to get higher current.
Vellman Kit is K1823, replace LM317 IC Regulator with an LM338T and change diodes to 1N5408 rectifier diodes the diodes will limit the power to 3 amps, but at a squeeze 6 amp diodes will fit, 6A10, either set of 4 diodes are a direct replacement for the 1 amp diodes in the kit, 1N4007. As is the voltage regulator, 3 amps for slot cars should be fine, and replace the horizontal preset potentiometer with an off the board rotary or sliding potentiometer of 4.7K oh on a final note the kit is available in most parts of the world.
I only suggested a kit configuration as it will uncomplicate things if you build a variable voltage regulator circuit, but if you want you can build a custom one from scratch, its up to you, but the units look like an ideal slot car psu contender.
Dave.
PS, The replacement parts are available at all good electronic retail stockists, or on the kit link site, under components as a PDF file of there components catalouge, but other electronic stores sell all the above including the kit.
http://www.esr.co.uk/velleman/products/index_kit.htm
