Barman's V-8 Engine Building Instructions/ 2,862 Parts

[Tcp]

So I almost got all my parts for this build. I got the train regulator but didnt know I would need an ac adapter. So I found one specs are within limits but seems a lot weaker when I hook it up to my crane 42009 compared to the battery pack hook up. Is this normal? Or is the adapter incorrect? Input: 120VAC 60Hz 14W Output: 9vDC 800mA.

[Blakbird]

800mA is a little low, but should run the engine without any problems. I use a 1.2 Amp transformer at 12V. Using it for running the crane is probably a little low on power; should be at least an amp. Also make sure you have good clean terminals on the regulator because dirty terminals will lose voltage.

Something is strange about the rating of your transformer. If it is 9V at 800mA, then thats 7.2 Watts, not 14 Watts. I don't know how they can claim 14W when it is only half that. Suspicious.

[bonox]

I don't know how they can claim 14W when it is only half that. Suspicious.

the input is 14W, the output is 7.2W.

50% efficiency

[DrJB]

Also, and if I recall correctly, the power adapter needs to output AC voltage, not DC. Gotta dig out my official lego adapters and read the fine print.

the input is 14W, the output is 7.2W.

50% efficiency

That can't be, 50% losses for transformers? That's on the high side. Unless it's a cos phi factor missing somewhere:

For DC machines: Power = Current × Voltage

For AC machines: Power = Current × Voltage × Cos(Phi)

Behind heaters, transformers are the most 'efficient' electrical machines as there are no moving parts/friction/losses.

Edited February 3, 2015 by DrJB

[Blakbird]

Also, and if I recall correctly, the power adapter needs to output AC voltage, not DC. Gotta dig out my official lego adapters and read the fine print.

No, no! There's never been a Lego that should use AC power. All Lego motors, controllers, battery boxes, and regulators have been DC. You'll instantly fry your regulator with AC. Luckily, I don't think anyone makes such a thing as an AC transformer for consumer use, so it is hard to screw up.

I'm not sure how the AC rumor ever got started. I can't think of any toy that runs on AC. I think at some point people got confused because people were calling it an "AC transformer" because it plugs into the wall, but of course if it output AC then it wouldn't be a transformer.

That can't be, 50% losses for transformers? That's on the high side. Unless it's a cos phi factor missing somewhere:

That does sound terrible. I've also never seen a transformer rated for input power since that would be meaningless. It would just be telling you how much it is going to heat up your room! The output is always the rating.

[DrJB]

No, no! There's never been a Lego that should use AC power. All Lego motors, controllers, battery boxes, and regulators have been DC. You'll instantly fry your regulator with AC. Luckily, I don't think anyone makes such a thing as an AC transformer for consumer use, so it is hard to screw up.

I'm not sure how the AC rumor ever got started. I can't think of any toy that runs on AC. I think at some point people got confused because people were calling it an "AC transformer" because it plugs into the wall, but of course if it output AC then it wouldn't be a transformer.

Well, it's more than a rumor. In fact, I just went upstairs and grabbed one I had, and below are a couple of pictures. I know this topic had been debated on multiple occasions, and it's difficult to reach a final answer, but one cannot deny the print on the back of the transformer ... unless it's a typo. The next thing is to hook up the output to an oscilloscope and put this to rest. What I do not recall however is whether I got that transformer with the Express Deluxe Train 4535-1 or with the Technic Control Center II 8485-1

Edited February 4, 2015 by DrJB

[DrJB]

Adding to the above post, and that's really getting confusing, is that a search on BrickLink of item 70931 brings up the picture below, which says the output is 12 VDC. Note however that the inscriptions on the back of the transformer do not mention LEGO at all (in contrast with my prior post/picture).

Here is another picture from peeron.com, where the printed output is 10 VAC (not 12)

and yet another picture off the net, with 10 VAC and and 7 Volt-Amps of 'apparent' power (not Watts)

Edited February 4, 2015 by DrJB

[Blakbird]

Well, that clears up where the rumor got started. Some of the transformers are mislabeled. Rest assured, they all output DC. If you actually have access to an oscilloscope, it would surely be interesting to see the output. If the output were actually AC, you'd expect a frequency to be listed (i.e. 60 Hz).

Obviously anything designed to run on batteries but that can also be plugged into the wall is going to need to be DC. All LEGO motors including train motors are DC.

[bonox]

That does sound terrible. I've also never seen a transformer rated for input power since that would be meaningless. It would just be telling you how much it is going to heat up your room! The output is always the rating.

have you not had much to do with linear supplies? Old laminated core transformers in plug packs were often that poor, especially the unregulated ones. The newer switch mode supplies are much better, but still rarely exceed 80%.

The input is also very relevant. There's no point basing your input power requirements on an output without knowing the efficiency of the device. In leiu of efficiency, they will commonly have an input power specified. Probably quite meaningless for tiny output devices, but when you're talking about 1200W (output) computer supplies there's a great reason they tell you that you'll need a 16A circuit if you're running on less than 200V input!

Other examples:

[Blakbird]

The input is also very relevant. There's no point basing your input power requirements on an output without knowing the efficiency of the device. In leiu of efficiency, they will commonly have an input power specified. Probably quite meaningless for tiny output devices, but when you're talking about 1200W (output) computer supplies there's a great reason they tell you that you'll need a 16A circuit if you're running on less than 200V input!

Hopefully it was clear that we're talking about transformers for powering LEGO motors here, not computers or industrial applications. In this context, input power is meaningless. All I care about is that I'm getting somewhere in the neighborhood or 9-12V at somewhere in the neighborhood of 1 Amp max current. The power that it takes at the wall to provide me with that doesn't really matter as long as it is less than the 15A at which the household breaker will blow, and you'll never get anywhere near that no matter how inefficient the transformer is.

My point with the rating is that when you buy a "10W transformer", you should reasonably expect that it provides 10W of usable power, not that it consumes 10W at the supply. 10 Watts is a reasonable target for purchasing a transformer for use with LEGO.

To get back on topic, the transformer you should use to power the train regulator for Barman's V-8 should be 9-12 Volts DC and capable of 1 Amp (1000 mA) or more. More doesn't hurt you. Something like this:

http://www.radioshack.com/nte-57-9d-1000-3-ac-dc-9v-1a-1-35mm-plug/55057421.html#q=AC/DC&start=4&tab=tab3

[bonox]

hey, it's an explanation of something you said is suspicious and misleading. It's neither (both input and output are specified in this example at post 26) and applicable to any power conversion device, whether team america believes in it or not! I'd have thought that was fairly obvious to an engineer and that transformer is not (to my knowledge) advertised as a 14W output device anywhere.

Whether it will blow your supply breaker is irrelevant - you're still getting confused by what the nameplate on the device is telling you, whether it's for lego or not.

[DrJB]

hey, it's an explanation of something you said is suspicious and misleading. It's neither (both input and output are specified in this example at post 26) and applicable to any power conversion device, whether team america believes in it or not! I'd have thought that was fairly obvious to an engineer and that transformer is not (to my knowledge) advertised as a 14W output device anywhere.

Whether it will blow your supply breaker is irrelevant - you're still getting confused by what the nameplate on the device is telling you, whether it's for lego or not.

Let's just cool it off here. This topic is not about 'lecturing' people. We're all grown-ups (I hope) and expect some civility, and what the heck is Team America?

No one is confused, and I advise you read the prior discussions that lead to this specific one before jumping in and calling people names! This just shows some immaturity from your side.

The topic being discussed IS suspicious AND misleading. You only need to see the variability in all the specs of the Lego parts (as I stated in post #32) to 'appreciate' the source of confusion. We've all had university courses in electrical engineering and are trying to approach this from that level. If we have something positive to bring to the table, so be it. Else, be quiet and move on.

Going back to our topic, I'll take the example from my prior post: The input power is 4.5 Watts, whereas the output power is Voltage×Current = 12×0.2 = 2.4 Watts

This suggests an efficiency of 2.4/4.5 = 53% ... This is very low (from my experience). I'm not the expert on transformer design but, can anyone explain what type of losses make this transformer so inefficient ... or is it the 'Made in China' label suggesting poor quality and workmanship?

Edited February 5, 2015 by DrJB

[bonox]

Anyone one to shed some light as to why the efficiency of such transformer is so low?

would you like an answer, or is it going to be treated as a 'lecture' like posts 29 and 37?

The input value is a maximum and may not be what it draws at the rated output. It may also include an inrush current component, however this is unusual and tends to appear in specification sheets for supply installations of large units, not little wall warts.

You also state above that transformers are close to perfect because they have no "moving parts/friction/losses". That's not quite right as there are losses involved in quite a few ways in transformers - type, construction, material, frequency etc - and there's a valid reason for transformers carrying cooling jackets or otherwise getting warm. If there were no losses, they wouldn't heat up. Sadly they do (but the new switch mode units much less), which is why they get warm, even when not actually loaded.

One of the biggest losses comes from lower quality materials and or construction (where you get significant loss in the core from hysteresis or a poorly constructed laminated core having the plates move around and the friction between moving plates causes heating and noise losses). A big power distribution transformer can exceed 95% efficiency because they are made well with good materials and tend to have fairly tight operating criteria.

In this case, the plug pack may be expected to deliver anywhere from 1 to 800mA; at some point in there, it'll probably draw up to 14W. That doesn't mean it'll draw 14W at every load (or even at maximum load). Also keep in mind that if this is an unregulated pack you'll get perhaps 15V out of it with no load. You'll get losses from voltage drop in the rectification diodes, plain winding loss from relatively high resistance wire, core losses, resistance at internal connections (it's a small cheap transformer after all) and if they're a really conscientious designer, they'll account for loss in the wire all the way to the plug. You'll find the new switch mode units have much better performance, which is one reason (along with universal input voltage) for them pretty much replacing all the old linear units.

I note from wikipedia that

Considering the total efficiency of power supplies for small electronic equipment, the older mains-frequency linear transformer-based power supply was found in a 2002 report to have efficiencies from 20–75%

http://en.wikipedia....pter#Efficiency

edit:

If the output were actually AC, you'd expect a frequency to be listed (i.e. 60 Hz).

whilst not disputing the rest of your argument about providing external power to something running on batteries, expecting an output frequency would rarely to never happen on a transformer since output frequency is always the same as the input (and the input is specified). You can get lead/lag issues with regard to when the maximum rise and fall occur, but the frequency will always match. The only exception would be a frequency converter or inverter, but if you want to focus on lego, this is getting way out on a limb.

also

No, no! There's never been a Lego that should use AC power. All Lego motors, controllers, battery boxes, and regulators have been DC. You'll instantly fry your regulator with AC. Luckily, I don't think anyone makes such a thing as an AC transformer for consumer use, so it is hard to screw up.

I'm not sure how the AC rumor ever got started. I can't think of any toy that runs on AC. I think at some point people got confused because people were calling it an "AC transformer" because it plugs into the wall, but of course if it output AC then it wouldn't be a transformer.

not sure where this is coming from, but all transformers output AC. As far as providing AC to a control box like the lego 'regulator', are you aware of whether the thing has a diode bridge as its input stage? If it does, it would enable it to cope with DC polarity reversal or also accept an AC input, which would match the pictured transformer and not "instantly fry your regulator". I'm aware of a large number of older train power controllers that use 18VAC inputs.

edit2: There also seems to be proof of this:

http://bricks.stacke...speed-regulator which even has the plastic body with an 9-12VAC input cast into it which would imply that the prior statements about incorrectly labelled supplies is not quite correct.

ie, if you have a train controller, you don't need a DC power supply for it.

Edited February 5, 2015 by bonox

[bonox]

on a different note and back to the moc, is anyone else having trouble finding 1x6 thin liftarms south of the equator?

[Tcp]

Wow look at what I started.... I'm at picture 117 and got a question. What is the timing on the cam gears for the 8 pistons? Say we start with the first two pistons (in order of install) with the pointy part of the gear pointing up (12o clock).... where does the next set of gears point (9o clock)? Then 6 then 3???

Edit: Nevermind I found it in the renderings thanks for all the great detail!!!

Edited February 11, 2015 by Tcp

[Tcp]

on a different note and back to the moc, is anyone else having trouble finding 1x6 thin liftarms south of the equator?

yeah they are hard to find and if you do find them its like a dollar each.

[bonox]

I think i've managed to get enough scraped together to start building and looking forward to it. I can't see why a cam alignment procedure from any real engine wouldn't work with this one, but you could begin by putting cylinder 1 at top dead centre, aligning the cam to have closed valves at that point and then turning it over to see if the rest of the bank lines up.

I even have a 12V AC power supply to plug into my controller.

[DrJB]

The input value is a maximum and may not be what it draws at the rated output. It may also include an inrush current component, however this is unusual and tends to appear in specification sheets for supply installations of large units, not little wall warts.

This is very clear (to me ). When you plug any device into an electrical supply, the voltage is decided by the power supply, and the current is decided by the impedance/resistance of the load. In addition, power supplies have a max-rated power to prevent them from overheating/melting. This means the max current out of the power supply is 'limited'.

You also state above that transformers are close to perfect because they have no "moving parts/friction/losses". That's not quite right as there are losses involved in quite a few ways in transformers - type, construction, material, frequency etc - and there's a valid reason for transformers carrying cooling jackets or otherwise getting warm. If there were no losses, they wouldn't heat up. Sadly they do (but the new switch mode units much less), which is why they get warm, even when not actually loaded.

Nuances. I did not say transformers were perfect, but their efficiency is somewhere in between that of motors and heaters. I recall measuring the efficiency of a transformer during a physics course many many years ago, and the number was in the mid 80's.

One of the biggest losses comes from lower quality materials and or construction (where you get significant loss in the core from hysteresis or a poorly constructed laminated core having the plates move around and the friction between moving plates causes heating and noise losses). A big power distribution transformer can exceed 95% efficiency because they are made well with good materials and tend to have fairly tight operating criteria.

We seem to agree on this, it's cheap materials and poor workmanship that are responsible for low efficiency.

So, back to our topic then, and to finalize the AC/DC discussion, Would you agree to the following?

1. Lego Train Controller and Technic Control Center can operate with either AC or DC power adapters.

2. There is a 4-diode rectifier bridge inside both controllers, followed by a cap (low pass filter) to smooth-out the ripple

3. If the adapter is AC, then the diode bridges rectifies the voltage

4. If the adapter is DC, then only 2 branches of the bridge get used, not all 4 of them.

To me, it seems Lego choose to have their controllers operate on AC simply as a precautionary measure. No one knows how 'non-clean' the adapters from China would be, so Lego decided to do the conversion AC/DC internally in their controllers. It also could be a cost idea? An AC/AC power adapter might be cheaper than an AC/DC. In the end, the customer (you/me) is the ultimate winner as the controllers work with either AC/DC.

Edited February 11, 2015 by DrJB

[bonox]

So, back to our topic then, and to finalize the AC/DC discussion, Would you agree to the following?

1. Lego Train Controller and Technic Control Center can operate with either AC or DC power adapters.

2. There is a 4-diode rectifier bridge inside both controllers, followed by a cap (low pass filter) to smooth-out the ripple

3. If the adapter is AC, then the diode bridges rectifies the voltage

4. If the adapter is DC, then only 2 branches of the bridge get used, not all 4 of them.

yes. Also worth noting that the same mistaken arguments pop up in a different thread I found today

http://www.eurobricks.com/forum/index.php?showtopic=83788

regarding the Control Centre. The same issue was addressed, but not accepted by some parties. Your post in that thread even stated what you repeated here.

To me, it seems Lego choose to have their controllers operate on AC simply as a precautionary measure. No one knows how 'non-clean' the adapters from China would be, so Lego decided to do the conversion AC/DC internally in their controllers. It also could be a cost idea? An AC/AC power adapter might be cheaper than an AC/DC. In the end, the customer (you/me) is the ultimate winner as the controllers work with either AC/DC.

I have no basis for claiming what TLG's design decisions may have been at the time. You could certainly postulate that for an international market, a product that will accept an AC or DC input is likely to be more robust in the hands of consumers. Extra low voltage AC inputs used to be fairly common (hands up if you ever had a hornby train set or an analogue computer modem) but seem to have died out, probably because it's cheaper/smaller/cooler to put the conversion and regulation circuitry in the plug pack than have to handle it in a small device like a mobile phone for example. Whatever the real answer is, your last sentence is certainly true.

On a great plus note, I'm getting a second train controller today, so I can leave it bonded to the engine. Really looking forward to this one

[DrJB]

... I found today http://www.eurobrick...showtopic=83788 regarding the Control Centre. The same issue was addressed, but not accepted by some parties. Your post in that thread even stated what you repeated here. ...

Thanks. I had totally forgotten about that thread. It's good that my story is consistent

Edited February 11, 2015 by DrJB

[Tcp]

Ive finally gotten to the end of the build... A very fun and great build!!! The only problem I encountered was with the flex axles for the headers. Says to use flex axle 16 32202 but they are too short cant fit the 27 pieces as noted in the instructions and doesnt reach the block on some of the heads. Going to try and get the axle 19.... Has anyone else had similar problems?

[Blakbird]

Ive finally gotten to the end of the build... A very fun and great build!!! The only problem I encountered was with the flex axles for the headers. Says to use flex axle 16 32202 but they are too short cant fit the 27 pieces as noted in the instructions and doesnt reach the block on some of the heads. Going to try and get the axle 19.... Has anyone else had similar problems?

I just bought a spool of tubing and cut it to length after the plates were attached.

[bonox]

I used third party 19L axles for mine - it could do with a few more than 27 plates to cover the axle though. I'm happy with mine, but I would agree with BB about using plain tube instead. It's a small pain to trim the ends off another set of softies.