# How to make a power supply variable



## Hornet (Dec 1, 2005)

Couple Variable voltage articles using LM style regulators,first one is close to 10 yrs old and comes from Brent Carlson.

http://slotcars.carlsoncomputers.com/articles/slotcar_powerbase/variable_power_base.htm

The second one is from Rich Dumas.

http://www.slotcarillustrated.com/portal/forums/showthread.php?t=33667


----------



## Hornet (Dec 1, 2005)

Enough views it looks like some guys are interested in voltage regulators.
Here's a link to my learning experiences with them.

http://routedtracks.yuku.com/topic/27/Voltage-Regulators

Pic's

http://routedtracks.yuku.com/topic/28/Rick-s-boards-for-Dave-to-see

If you use a 2500 (2.5K) ohm pot and a 1000 (1K) ohm pot tied in series ,you'll get a variable voltage set-up that gives you a coarse and fine voltage adjustment,and doesn't need any extra resistors.
The 1K pot gives roughly a 6 to 7 volt variation as a fine adjustment pot,and the 2.5K pot is the coarse adjustment pot.
This set-up will let you take the voltage from roughly 23 volts to 0 volts.If you add 1500 ohms resistance in series to this set-up,it'll give you approximately from 30 volts to about 9 volts as the low end setting

I settled on 2 pots for my regulators,and haven't had any problems with them

Post 74 shows the pots

http://www.hobbytalk.com/bbs1/showthread.php?t=331698&highlight=Routing+Sintra&page=5


----------



## Mike(^RacerX^) (Mar 15, 2003)

I have nothing to add to your thread,just taking an opportunity to pop my head out and say hello:wave:

I will soon be in a situation wher I can do what ever the hell I want.Like a slot car track in the living room.And possibly a drill press.

I have a ton of HO stuff,but some of the digital 1/32 stuff intrigues me.

In the end,I will probably stick with HO.Something simple to build motors,like a 20 foot 2 lane oval,and then maybe a small 2 lane set up on one of those cheapo walmart folding tables.I want to try winding some more t jet arms.I have a possible source for a watch makers poising tool.I will share this stuff when it transpires.

Back to your original topic,which made me laugh.

Some of the most epic flame wars that ever took place on the internet took place on HO slot car boards on threads that dealt with power supplies.

Fantastic battles,guys threatening to beat each other up,guys jumping off of buildings and in front of moving buses.....it was NUTS!!!

Funny how it seems this hobby seems to cycle up and down over the years.

Good times....I can never stay away for long!!:wave:

Mike


----------



## Hornet (Dec 1, 2005)

LOL,good to see you Mike,it's been too long:wave:

Those were the days huh

O O,i remember your old basement,i'm just imagining a place with no limits,lol:wave:
It'll have to come with a map,lol lol

Any big track plans for the new found freedom

Take care Mike
Nutbar Rick:thumbsup::wave:

Hows the guitar building going these day:thumbsup:


----------

