slot car track

[goner19]

so santa brought the kids a new slot car track from carrera
its really cool
but it runs on 4 d cells...
didnt last past 3pm xmas day

so i hacked it to run from a 6v 600ma 3.6va wall wart

only problem is when one car stops the other car get too much jucie and flys off the track

i need to wire in a cap or a resistor of some sort to even out the spike when the power jumps

any suggestion would be grand!

t.i.a.

G-

[Robert Reed]

Why not a 7805 with a small resistor in its ground leg to boost to 6 volts and max out at that point?

[Externet]

If the effect does not happen using D cells, sounds interesting. But replace the wall wart with one with same volts, more current capability... like over one Ampere. The thing is to maintain the voltage stable with one or both cars running.

A voltage regulator as Robert says should work too, but make it a 78T06 instead of a 7805, fed by an over 9V/3A wall wart.
Miguel

[jimmy101]

A D cell will source a fair amount of current, perhaps 20A or more. If the track is burning through the batteries pretty quick then it's likely that track is pulling more than the 600mA the wall wart can supply. Hook an amp meter in series with the track and see how much current it is drawing.

You need a beefier power supply. There a good chance that the track will work with a 5V supply (it certainly can't be hurt by 5V since that batteries will put out that voltage as they die.) So, do you have a 5V computer power supply laying about? You'll need a couple 10 ohm 5~10 watt resistors as ballast for the power supply. (Or, you might be able to just use 120V light bulbs as loads.)

I don't think a voltage regulator will work with the current setup. The wall wart can't source enough power so the regulator will not be able to maintain voltage. A regulator and a 9V or 12V supply might work but you probably still need a supply of at least an amp or more.

[reloadron]

I would check the voltage out of the wall wart. A 6 Volt wall wart in most (not all) cases is an unregulated DC out and most put out much more than their rated voltage. I like the idea of using a 7805 with a resistor in the common leg so you can adjust for 6 volts but you will need likely about 8 volts or more to get it working. Maybe feed the 7805 with a higher output voltage wall wart?

Ron

[Robert Reed]

Goner
From your post I assumed your voltage was holding up under load and only soaring when the load was reduced (i.e.-car(s) fall off track. My suggestion was NOT for regulation, but rather to limit the voltage soaring when that takes place. Much better way than a clamp zener. It would only take 2 minutes to haywire together and patch in. If it works-great. If it does not- then on to bigger and better things.

[goner19]

you guys rock!

i love forums with good positive feed back
not just a bunch of meanies full of put downs!
=)

i have a gallon (literally its a bucket) of wall warts
i just chose the 6v cause i know it was the same as the 4 d cells put out
truthfully im not so good in the amp department

im kinda finding that the lil 6v wall wart aint cutting it any ways

ive got some 7805's laying around
i have just figured out the whole regulated 5v power supply deal with two caps on the base and the emitter

im not so sure about how id put a resistor on the common ...
i mean i could phyical do it ...but not sure id do it right...

would i just run my 9v wall wart to the base and out emiter and the resistor to the common and ground? no caps needed?
i hope the link below works...




thanks again guys!!!!

(and btw this slot car thing is becoming a disease...=) )

[Bob Scott]

I remember that the cheap slot cars in the early '60s used braid brushes to pick up power on the slots. The transformer output was AC.

Independent rheostat control of two different cars was possible even if the two cars were in the same slot. Each car had a "top hat" rectifier diode in series with the motor, one installed backwards from the other so that one car used + current from one half of the AC cycle and the other car used - current on the other half of the cycle. The same was true for each rheostat pistol grip control. Each controller had a diode in series with it but one was in reverse position to the other. That is how they achieved independent speed control of two circuits.

So those cars did not use smooth DC, voltage regulators or filter caps. Everything worked OK. You don't need regulated voltage. To cure your problem you just need a larger wall wart that won't drop so much voltage under heavy load.

I use the same independent control system for my doorbell wiring. The front doorbell button and chime use the same wire pair as the rear doorbell, but each button activates a different buzzer/chime in a different location.

I should say "a similar system" because I have the diodes connected in parallel across each chime and pushbutton because the chimes and pushbuttons are all in series.

[Robert Reed]

Goner
In your print of the 7805- to jack up the output voltage, insert a resistor in the ground leg. Start with 100 ohms and go up or down from there to get desired voltage. 1/4 watt resistor is sufficient. As to the transistor solution- run a zener supply from the wallwart's filtered output and drive the base of a power pass transistor with it, emitter to the track output and collector to the wallwart's filtered output. I can't give any details because I don't know exactly what your requirements are, but the zener voltage should be 1/2 volt higher than the desired output. You will have to do some simple number crunching for load current, base drive, Hfe and so on. This is the beauty of the 7805 - so simple. Be sure to allow adequate "headroom" from the wallwart supply in either case. More headroom- better regulation and more wattage dissipation. Less headroom- lower wattage dissipation but poorer regulation under heavy load. Shoot for 2.5 volts of headroom under the heaviest load encountered.

[goner19]

hey thanks a lot guys...
i wont get a chance to try it till next year (pending hangover)
but i truely apperciate all the help

have a safe and happy new year!!!

[CeaSaR]

From everything I have come to understand about electric motors (which is nowhere near what others
on this forum know ), you have to have enough of both voltage and current to make one run at optimum
efficiency. So, even if the voltage is there (~6 V), if the current is not enough, the motor will be slow(er).


Let's look at the situation: D cells can source ~ 1 amp for a certain amount of time - enough to run your
cars around the track satisfactorily for (supposedly) the young'uns. Your "hack" can only source "up to"
600 milliamps, probably a wee bit less. Now, if you take into account that the cars may draw more than
300 mA each, then you can "assume" that they are actually underpowered. When you run only one car,
especially if you cut the second car off abruptly, you'll get an instant increase in amperage AND a voltage
spike, which sends the remaining car into dragster mode. With the batteries, you don't get that sort of
problem because with wear, they drop in both voltage and current, therefore preventing such drastic changes.

Hope I explained this correctly. If not, would one of the members of "higher schooling" correct me, please?

What Robert, Bob, Externet, Relodron and Jimmy101 are suggesting makes absolute sense, in that a regulated
supply will more closely simulate a battery in it's power delivery characteristics, keeping things from spiking
too much.

BTW, just last summer I found that there were 2 slot car tracks within 20 miles of my home. You might find
that a local hobby shop can help you locate one if racing gets deeper in your blood. My youngest is bugging
me to get into it again, after almost 30 years.

CeaSaR

[goner19]

hey ceasar
im sure that pretty well sums it

i just pulled out a 24v ac transformer that i got at a local junk store

im in process of building a bigger and better track
proably form scratch ...
i got a 5603 retifier im got hook it up and see what i get out of it

http://www.hoslotcarracing.com/

has tons of info....

thanks again.

[Janitor Tzap]

Wow,
Now that brings back memories.....

I use too have an HO-Gauge Aurora Model Motoring/AFX set.
It used a 18VAC Transformer with rheostat speed controllers that had a Brake Button, Forward/Reverse switch.
The cars had guide pins on the front and back of the frame chassis.
So you could use Reverse backing down the track.

The Carrera Slot Car set you purchased.
Are they the 1/32 scale, or the smaller 1/64[HO Scale] scale cars?

I looked at a few sites that carry Carrera Slot Cars, and sets.
But, none had battery operated sets that I could find.

I agree with the others that a regulated supply will certainly solve the voltage and current spiking problem your seeing.

Well, if your kids really get into the sport.
I hope you have got room to setup a table and buy more track and cars.


Signed: Janitor Tzap

[goner19]

yeah the battery op set i got it at toy r us...
carrera #62180
the cars are about 5" long
so i guess they are sub 1/32 but bigger than ho


i hit my folks garage and pulled out a momogram set my mom brought from german for us
its in near mint condition....
too cool to play with

i build sets and props for a living
so building a track out of mdf is no problem
space for it ?
well thats something else....

i want to build a lap counter using a pic...
nuts a volts had an articale a while back
where a guy built a winners gate for a hot wheel track
anyone know what issue that was?

[Janitor Tzap]

yeah the battery op set i got it at toy r us...
carrera #62180
the cars are about 5" long
so i guess they are sub 1/32 but bigger than ho

Ok, I checked Toy R Us site.
They do list this set.
{I would of opted for the set that had the wall-wart power supply.}

i hit my folks garage and pulled out a momogram set my mom brought from german for us
its in near mint condition....
too cool to play with

Why let it go to waist?
Clean it up and use it with the Carrera Set.
I've looked, but I don't see Track Adapters to go from the Revell/Monogram Track to the Carrera Track.
But, if you ask around some of the hobby shops, or guys who have slot car tracks.
They'd probably know where you can get them.

i want to build a lap counter using a pic...
nuts a volts had an articale a while back
where a guy built a winners gate for a hot wheel track
anyone know what issue that was?

Here's a site that carries lap counters for the Carrera track.
http://www.hotslots132.com/index.php?cPath=92_385

Happy motoring!


Signed: Janitor Tzap