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Denney's New Track


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#21 kalbfellp

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Posted 27 April 2009 - 01:53 AM

This is the best value supply around.
DS 3800
They will onlt be available until stock runs out and will not be restocked.

Cheaper supplies will almost certainly be Switch Mode supplies.

Edited by kalbfellp, 27 April 2009 - 01:55 AM.


#22 gzminiz

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Posted 27 April 2009 - 07:40 AM

View PostDenney, on Apr 27 2009, 01:24 AM, said:

Hey Johnnyfly41. I may add elevations once I get the track running. Simple "cut and raise" method would probably work fine. I didn't have anything on hand that would work as a flexible strip so I just made a simple trammel to do the corners. The straights on the other hand are giving me a LOT of grief. Even though I line up the router at both ends, my straight lines still don't match up. Very annoying. I guess a bit of sanding is in order. :lol:

Don't know anything about the difference between switch mode power supplies.

I just found another supply: 13.8v / 0 to 12amp regulated ($70).

Where did you find that one? That is what i need, I found one on ebay a while ago but can't find it for that price.

If you want to get tricky, you can get the non-variable power supply and build the variable regulator into each drivers station so they can control their own lane. That is what I have planned. Pretty cheap for the components to do it. Most expensive piece is the LCD or Analog gauge to display the voltage.

#23 kalbfellp

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Posted 27 April 2009 - 10:38 AM

Quote

Pretty cheap for the components to do it

Have another look you should aim for about 4 to 5 amps per lane and it really needs to be regulated.

#24 gzminiz

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Posted 27 April 2009 - 10:59 AM

View Postkalbfellp, on Apr 27 2009, 10:38 AM, said:

Quote

Pretty cheap for the components to do it

Have another look you should aim for about 4 to 5 amps per lane and it really needs to be regulated.

12a should be good for upto 3 lanes nad he is doing a 2 laner. You can make it regulated by using a variable regulator and a pot to control the output voltage. All I am doing is taking what makes it a variable regulated power supply out of the power supply and into each drivers station. The components to do that part is cheap. In reality I just need a transformer to convert the 240AC to DC but a simple 13.8v 12a power supply is just as good and already has the heat dissipation taken care of for me.

#25 kalbfellp

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Posted 27 April 2009 - 12:22 PM

The regulator will need to be pretty big! I have seen 317K's give up the ghost,so will need at least two transistors off the regulator. All the tracks down here have 15 3055's for regulation! Plenty of grunt.

#26 Denney

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Posted 27 April 2009 - 12:26 PM

OK, a couple more questions... The D3800 isn't in stock at any DSE near me (I wish Chermside hadn't moved into the shopping centre, they have NOTHING now).

The 13.8v / 0 - 12a is from Jaycar: http://www.jaycar.com.au/productView.asp?I...mp;SUBCATID=381

I'm not sure if it's switch mode or not. Why is switch mode no good for slot cars?

@gzminiz: Do you have a schematic for the variable regulator? It's something that would interest me because then I can turn down the voltage for just one lane if that person is new to racing while still have the other lane at full speed.

#27 gzminiz

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Posted 27 April 2009 - 12:29 PM

View Postkalbfellp, on Apr 27 2009, 12:22 PM, said:

The regulator will need to be pretty big! I have seen 317K's give up the ghost,so will need at least two transistors off the regulator. All the tracks down here have 15 3055's for regulation! Plenty of grunt.
317 are only 1.5a, at least a 350 for double that (this is per lane, not for entire track) and should suffice for 1/32 cars and a 338 is 5A

shouldn't be any issues at that range. Heatsink and all is well

(edit: 15?? how many lanes? 317 and a 3055 per lane (3-4A per 3055))

Edited by gzminiz, 27 April 2009 - 12:38 PM.


#28 Denney

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Posted 27 April 2009 - 01:07 PM

Just rang around DSE stores and nobody has any of the D3800 in stock anymore. :lol:

#29 Denney

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Posted 27 April 2009 - 01:15 PM

Dick Smith sell another one which is 3-30v 20amp but it is a switch-mode power supply. What is so bad about switch-mode power supplies? Most, if not all, of the power supplies I can source now are switch-mode.

I know switch-mode means that instead of dissapating the excess power is turns the input on and off as needed but I can't see how that would affect the output that much.

#30 kalbfellp

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Posted 27 April 2009 - 01:52 PM

QLD:- Calamvale DSE, Carindale DSE, Dalby DSE, DSE Bundaberg (FRN), Gladstone DSE, Hervey Bay DSE, Kingaroy DSE, Maroochydore DSE, Toowoomba DSE, Townsville Powerhouse, Victoria Point DSE, Warwick DSE, Yeppoon DSE

All are showing stock. I had the same answer down here BUT found two stores still with them.

#31 gzminiz

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Posted 27 April 2009 - 01:55 PM

View PostDenney, on Apr 27 2009, 01:15 PM, said:

Dick Smith sell another one which is 3-30v 20amp but it is a switch-mode power supply. What is so bad about switch-mode power supplies? Most, if not all, of the power supplies I can source now are switch-mode.

I know switch-mode means that instead of dissapating the excess power is turns the input on and off as needed but I can't see how that would affect the output that much.

Well, depends on how fast it switches. The faster the better. Kinda imagine if you were to run your car at WOT then slam it close and smash it open and slam it closed constantly just to maintain 60kph as cruise through your neighborhood. Ends up killing your motor a lot quicker and uses a heck of a lot more petrol.

#32 Denney

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Posted 27 April 2009 - 02:04 PM

Here are the specs:

Ripple & Noise: 50mV peak - peak
Load regulation: 200mV typical (0 - 100% DC load)
Line regulation: 50mV typical

@kalbfellp: Rang around the three closest ones on that list and none have them in stock. The others would require a lot of driving (1+ hours) which would use up to much fuel.

Edit: Reading around, I've seen conflicting reports on where it works for some, doesn't for others. Seeing as it's the only one with 15+ amps and variable voltage that I can get in my area, I may just have to go with it.

Edited by Denney, 27 April 2009 - 02:11 PM.


#33 Johnnyfly41

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Posted 27 April 2009 - 02:50 PM

Denny,

a switch mode power supply may work just fine. it is impossible to make a blanket statement in that regard. I probably should have not confused the issue. A switchmode supply refers to how the voltage is regulated. Usually the regulater is swithching the bulk unregulated DC power on and off to charge up the filter caps. If anything could be a problem, it could be the no load condition. A few 12 volt track lights connected would take care of that if it was a issue.

Switchers are particularly useful where you need several secondary voltages. You use a primary of a transformer in series with the large filter caps. A multi tap secondary can then provide various voltages higher or lower than the original rectified bulk DC voltage. Perfect for things like a computer power supply.

My experience with switchers was in designing them for a specific piece of equipment, with known current draws for each voltage. In a fly back switcher, the current available on secondary voltages is reliant on the primary voltage drawing sufficient current. Typically, the primary voltage needed to be loaded in the range of 10%-90% for the secondary voltages to work.

I much prefer a lab type supply with a lot of current capability and solid regulation. I use three HP 6286A lab type power supplies. I bought them on ebay for between 60 and 80 dollars each. They are brutes and rock solid, 0-30 volts at 10 amps. Remote voltage sensing, I dont use it and adjustable current limit with a meter for voltage and for current. To me, they are just about the perfect slot car supply, front and rear connections as well.

My Craperra wall wart, would float to over 18 volts with no load. With a mild RTR car under full power, it would drop to around 11 volts. You get used to it. when I first drove with my big supplies, the cars felt dead at low throttle. This is because of that high no load voltage of the unregulated carerra supply. ten minutes of driving and I couldnt tell the difference.

Sounds like guys have some potential other solutions for you. keep a eye on ebay in the industrial listings, I forget the exact place, but you can get to electric and electronic test equipment. I think there is even a topic for power supplies.

post pics of your track, we love pictures.

j

#34 Denney

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Posted 27 April 2009 - 03:43 PM

So the voltage could spike up with no load on a switch-mode power supply (or the voltage would spike down under load?)?

Say I bought the 13.8v / 20amp power supply... does that mean that the 13.8 WOULDN'T be regulated with no load? At the moment my understanding is very limited and to me it seems like a switch-mode power supply is opposite to what a regulated power supply would achieve. Arghhh.. damn electronics.

#35 SlotsNZ

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Posted 27 April 2009 - 04:32 PM

Switch mode supplies "adjust" the voltage in very short time periods, to provide regualted/stable voltage under varying loads.

I have heard from some electronic techs that the smoothing provided by switchmode supplies IN THEORY may cause incremental harm to some motors, but most of our home tracks use switchmode supplies, as did our old club track which ran "magnet sleds", and up to 12 amps draw on a supply rated at 25 amps. This was a during a period of a little over 2 years.

I use the same supply at home. We never found any problem with the supply, we "dead shorted" it quite a few times and it made groaning noises of protest, re-set itself in a few seconds, and carried on as before.

We didn't have any motor failures we could attribute to the supply, and the ease, pprice and simplicity of using them makes them a very suitable option

(IMHO)
And remember, all these guys with highly sensitive RF ham radio equipment use them as standard these days .... and I think their demands are just a little more precise than a little brush based DC motors we use.

So I think you are perfectly safe going with it.
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#36 gzminiz

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Posted 27 April 2009 - 08:23 PM

I am/was a hammy. A cheap switch mode can cause damage as it doesn't switch fast enough. Nothing wrong with switchmode as long as it is decent. With that said how much damage is negotiable. Might be negligble for our normal use. I guess it is more the faster it switches the less the risk (and probably the better components inside too)

#37 kalbfellp

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Posted 27 April 2009 - 08:54 PM

Typical Dick Smith don't update their stock as they all had them still listed as in stock! Sorry.

Edited by kalbfellp, 27 April 2009 - 08:54 PM.


#38 Denney

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Posted 27 April 2009 - 09:41 PM

It's all good. I ended up getting the 13.8v / 23a switch-mode regulated supply for Dick Smith. Came with a 3 year warranty to. :lol:

I tested it all out with the digital multi-meter I have any everything seems ok. It is adjustable from approx. 13 to 14.5 volts using a flat head screw underneath.

I swear I will post pics tomorrow. I didn't get much done today but tomorrow I want to finish routing the track and get it prep'd for paint.

#39 Denney

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Posted 28 April 2009 - 12:04 AM

Ok guys, here are the photos I promised. I have only made 2 routing mistakes so far. Not bad for my first time ever routing. Tomorrow I plan to finish my routing and get the tables prepared for painting. I also ordered my Phidget 0/16/16 interface board for PC Lap Counter today. Should arrive by mid week. :D

Here's the trammel I used for the corners:
Posted Image

Getting ready to start routing the tables:
Posted Image

All the corners routed, time for the straights:
Posted Image

Painting the test piece. Turned out rather well:
Posted Image

The power supply I settled on:
Posted Image

As usual, more photos in the gallery.

#40 kalbfellp

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Posted 28 April 2009 - 12:22 AM

IMO the 13 volts might be too much on such a short tight track,you will probably need spme heavy cars. We run up to 13.2 on my 65' track and our cars are uo to 130 grams. We are now running at 12 volts for most class's as the DUPR is run at 12 volts.





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