DIY power supply for Technic Control Center II

[le60head]

SOLVED! Thanks to Blakbird, i learned that the TCC II works just fine with DC, although the input jack is labeled with "~".

Feel kinda stupid now that i've learned that the problem i was trying to solve is not there to begin with :)

Hello guys! I am in need on advice / help!

First of all, i want to apologise if i have selected the wrong forum for my question. I think this might concert a lot of people in general, who would like to try and make their own power supply compatible with Train Speed Regulator / Technic Control Center II / Mindstorms RCX 1.0 with jack plug, That's why i hope its for this topic to be here.

I got my hands on one of these:

For those of you unfamiliar, that's a technic control center II from 1995.

MY GOAL

I intend to use the TCCII for bench testing while i'm building. It would be much easier to use than having to connect batteries and/or IR receivers each time, and it would have a consistent power of 9 volts at all times - just Plug & Play ;)

Also it seems to be a suitable power supply for exhibitions, so that's a plus too.

I chose the TCC II (technic control center II) over the first version, since it has a transformer input, and i read somewhere that its current limit is higher. How much, i do not know unfortunately.

(One could probably modify the first TCC to enable it to be powered by a transformer instead of batteries, but that's a different story.)

Here is where i need your help and superior competence :)

All i know is, that the TCC II needs to be powered by a 9-12 volt AC transformer. Unfortunately i do not know how much current it can handle.

So far i've narrowed down my options to these 3:

Option 1:

Use an original LEGO AC transformer.

I do not know if there is an official transformer, which is supposed to be used with the TCC II. ( If you do, please let me know! )

My bad! According to bricklink, this transformer came together with the TCC II set:

http://www.bricklink...tem.asp?P=70928

Its 10 v AC, 7VA . It is the same transformer that is used with the LEGO Train Speed Regulator.

I've tried using it, and though it worked, from my experience the transformer didn't provide sufficient current to run power hungry motors (XL, RC Buggy motor), especially more than one of them.

That is the only original LEGO transformet that i've tried. If you know of another that is more-powerful and can be obtained, please share the info :)

Option 2:

Buy an off-the-shelf 12v DC transformer and modify its output to AC.

In short, this means buying a 12v DC transformer and removing or disabling the AC to DC conversion. I expect this to be the easiest option.

What remains for me to find out is how much amperage would be sufficient to use with the TCC II, in order to use its full capacity ( reach its current limit ).

Luckily i have an old ATX PSU that i could try to adapt for this purpose.

Option 3:

Build a DIY power supply from scratch.

This idea implements buying a 12 v ac transformer and soldering input and output wires to it. Also, i suppose i will need to add some kind of filtering and protection.

Since i lack any knowledge in this matter, i think it would be safer and easier for me to choose the second option.

Those are my thoughts so far.

I would really appreciate your input on this topic :) Thank you in advance!

Edited June 21, 2013 by le60head

[AlmightyArjen]

If there´s an AC input on the thing, there´s probably a AC-DC converting circuitry inside. You can also screw it open and connect a 9V DC supply at the output of this circuit. Or does this go beyond your electronic capabilities?

[le60head]

Arjen, thank you for your suggestion.

I'll check if i can identify the ac to dc converter inside the TCCII. Im not an expert, but hopefully i will be able to figure out how to bypass it.

Still, i would like to see what it would take to make an AC transformer to do the job.

Edited June 21, 2013 by le60head

[AlmightyArjen]

To make a nice DC/AC converter is quite a hassle, google on it and you'll see

[le60head]

i do not intend to make a dc -> ac converter. I'd rather buy a readily available DC transformer, and remove or bypass its AC to DC conversion.

[robertd]

Hi,

as far as I understand this unit has the option to be battery powered or powered by the AC-transformer.

Since there are various DC transformers available in every electronic store, and of course batteries deliver DC power, my try would be to

- either build an adaptor to fit into the battery compartment instead of the batteries

- or to wire the installed jack to the battery contacts and use it with a DC transformer

I'd prefer the first option, since you wouldn't have to change anything on the unit. You just leave the battery cover away when you use it with plug-in-power (or if the battery cover must be on during use you'd have to cut a small slot into it to lead the cables out).

cu,

Robert

[le60head]

thanks for your input!

That sounds like a safe way of doing it. I would have to use a 9v dc regulated transformator then.

I have found a small PSU from a mini-atx. It outputs 6 ampers on 12 volts. I guess it would be perfect for the job, if i could bypass the ac to dc conversion.

[Blakbird]

I use an off-the-shelf 12V, 1000mA transformer for my Control Center. Works great. Using a larger transformer doesn't hurt anything. For example, you could use a 20Amp transformer if you could find one. The Control Center will only draw as much current as what it needs, and that need will always be regulated so you don't have to worry about burning anything out. Just don't try to use a higher voltage. The Control Center was not designed for XL motors though and my guess is that it won't power more than one at a time at full torque.

I use the Control Center to power PF models at conventions pretty regularly. It can power a model all day with multiple motors. I have never attempted to find the current limit, but I think it is low.

[le60head]

That's great info, thanks a bunch!

just want to make sure i got you right:

By 12v off-the-shelf transformer, do u mean AC?

Also, from what u said i understand that the control center has built-in regulator, so i shouldn't worry if my transformer is regulated or not.

[Blakbird]

Transformers convert from AC to DC. AC comes out of the wall, and you want 12V DC to your Control Center. Transformers are not regulated. They supply what the load calls for, up to their capacity. Get as big a transformer as you can to make sure that your motors are limited by the Control Center and not the power supply.

[le60head]

Thanks for the clarification, blakbird!

So you use ac to 12v dc transformer for your cc. I was asking you that, since it is labeled "9-12v ~" on the control center itself, meaning ac power input.

If i can use 12v dc for it, than there's no probem at all :)

Once again - thank you for clarifying my doubts!

[Blakbird]

To clarify "~9-12V" is not AC power input. It is DC power input. You absolutely cannot connect AC power to your Control Center. That's why you need a transformer which will supply DC power converted from your AC wall plug.

Notionally, you could connect a 12V DC car battery to your Control Center directly and it would run almost forever. There would be nothing wrong with doing this.

[1974]

Transformers convert from AC to DC. AC comes out of the wall, and you want 12V DC to your Control Center. Transformers are not regulated. They supply what the load calls for, up to their capacity. Get as big a transformer as you can to make sure that your motors are limited by the Control Center and not the power supply.

Not quite true. Transformers can only convert AC voltage to another AC voltage. Transformers as such are not regulated, but will give their rated output voltage at the rated load. A much smaller load (or none) will give a rise, sometimes up to 20%, in voltage

A PSU, which is a transformer with a rectifierbridge, smoothing capacitor and - but not always - a voltage stabilizing curcuit is something different

[Blakbird]

Not quite true. Transformers can only convert AC voltage to another AC voltage.

I agree that this is what the word technically means, but when you go to the store to buy a "transformer", it is always an AC/DC converter. That's just the consumer use of the word. Commercial transformers such as are used by utility companies step AC voltage as you describe.

[le60head]

I spoke to a friend of mine, and i think i figured out something significant.

Both the LEGO Train Speed Regulator and the LEGO Technic Control Center II are sold together with the 10v AC, 7VA transformer (shown in the first post in this topic). For that reason the input for both is labeled "9-12 v ~"

Thanks to Blakbird i learned that the LEGO Technic Control Center II works just fine with a DC transformer, although it was originally sold with an AC transformer.

Though this is just a guess, the Train Speed Regulator would work with DC as well, but perhaps it will be unable to alter the output voltage. ( i have not tested that)

[Blakbird]

Thanks to Blakbird i learned that the LEGO Technic Control Center II works just fine with a DC transformer, although it was originally sold with an AC transformer.

No, no, this keeps getting mixed up. We're talking about the same thing. The Control Center came with an AC/DC transformer which is the same thing I am recommending that you use. You cannot run your Control Center directly on AC. If you try to do this it will fry immediately. Forget about anything AC. You need a transformer that produces 9-12V DC which is the same thing the batteries do and the same thing the original transformer that came in the box did.

The original transformer that came in the box was not AC. I'm not sure where that idea came from. If you look closely at the label, you will see that the input is 200V AC at 50 Hz (European standard) and the output is 10V DC. The one that came in the box only supplied 0.7 Amps of current, so I'm suggesting getting a bigger one. 1.5A should do it.

[craig1]

Hi, I have a question about a power supply for the Control Center, after reading all this information I have found a power adapter at home, originally from a external CD drive that supplies DC power at 12 volts and 2 amps. It also has a symbol with a solid line over a 3 dashed line. It uses AC input 100 - 240 volt at 50 - 60 hertz and states it is L.P.S (limited power source)

I believe this adapter would be ideal to power the Control Center as it delivers DC power at the right voltage and amperage, however I am hoping you can confirm or advise if it will actually work safely. Thank you.

[Blakbird]

It should work fine as long as the plug is compatible.

[DrJB]

While it's true that the set was sold with an AC/AC transformer, using an AC/DC transformer won't do any harm. The second stage (low voltage) takes the 12 V AC and converts it to 9V DC via a rectifier (diode bridge) then a capacitor/zener to filter out the ripple. If you feed a DC voltage instead (from an AC/DC transformer), that DC output will simply gets regulated/stabilized further when it goes through the rectifier/filter stage. So, yes, you can use an AC/DC transformer instead of an AC/AC ... but the opposite is not possible.

[CP5670]

You can use any regular 12V AC-DC transformer with the newer control center, which you have shown above. I have several of them lying around and they all work fine with it.

It's a bit trickier to power the original control center (with yellow/red buttons) like this, since it does not have a plug for a transformer. I use one of the Radio Shack "hobby plugs," which is essentially a pair of bare wires that plugs into their lineup of adjustable-voltage transformers, with the plugs clipped to the battery contacts inside the control center. It's fiddly but works pretty well, and the wires stay in place without any soldering needed.

I use an off-the-shelf 12V, 1000mA transformer for my Control Center. Works great. Using a larger transformer doesn't hurt anything. For example, you could use a 20Amp transformer if you could find one. The Control Center will only draw as much current as what it needs, and that need will always be regulated so you don't have to worry about burning anything out. Just don't try to use a higher voltage. The Control Center was not designed for XL motors though and my guess is that it won't power more than one at a time at full torque.

I use the Control Center to power PF models at conventions pretty regularly. It can power a model all day with multiple motors. I have never attempted to find the current limit, but I think it is low.

The second control center is not too bad and seems to work with a single XL. A loaded RC motor will shut it down though. The first control center is much worse, and doesn't even handle a single PF medium motor properly.

[Blakbird]

For what's its worth, the old train regulators accept 9-12V DC input and power any of the PF motors very adequately. I use them all the time at conventions.

[craig1]

Hi, thanks for your reply, now I have another question if you can help. I bought the set on eBay and it came with the original Lego transformer but that transformer is from Britain and does not fit a US power outlet. I do have a plug converter that fits a US outlet and will connect to a British style plug, but I am unsure if this transformer will work with an American power supply as the voltage and frequency are both different (110 Volts and 60 Hertz in the US instead of 230 Volts and 50 Hertz in Britain).

Do you know if the transformer would work on this different voltage and frequency?