Buck converter. Great!

Correct.  Very very common easy-to-find connector.  Heck, even Radio Shack sells it! 

Or just search eBay for "5.5 2.1 plug" and you'll get over 10,000 choices of bare plugs, plugs with wires, adapter plugs, converter plugs, extension-cables, splitter-cables, you get the idea!

I build octopus cables for my Lemax buildings so I can power a bunch from one power supply.  A 5V regulated wall wart, one 3A diode, and half a dozen matching plugs on 6 foot cables and I can power a bunch of them.

I agree that 5V DC-output wall-warts are a zillion times cheaper and easier to find than 4.5V DC wall-warts.  BUT, in this case, I believe the issue is Menards, Lemax and the other building manufacturers do not (AFAIK) offer a solution for powering their 4.5V DC buildings via Accessory 14-16V AC.

Agreed Stan on the availability of 5V DC being easier to find.

So will a half volt difference really make all that difference to the Menards or  Lemax buildings?

Thanks

Dave

True Stan, that is a situation made for the buck converters.

Soo Line posted:

So will a half volt difference really make all that difference to the Menards or  Lemax buildings?

They specify 4.5 VDC, so that's what I give them.  Why take a chance for one five cent diode?

I like the ones forumite modified here with the digital voltmeter built in on the output side!

Yeah, accessory power from xfrmr was the task, then feed buss for connect to buildings.  Why would I want meter built in? Will the converter out voltage change/drift over time so I need to monitor that?   Oh, and Stan, found 20 plugs for $5 shipped at Walmart of all places!    What a country! TW

TedW posted:

Yeah, accessory power from xfrmr was the task, then feed buss for connect to buildings.  Why would I want meter built in? Will the converter out voltage change/drift over time so I need to monitor that?

Once set, the voltage will insignificantly drift/change with temperature, age, amount of buildings attached, and maybe even the phase of the moon. 

What baffles me is how Menards sells wall-wart adapters for buildings.  From what I can tell you choose the 1-plug adapter if you have 1 building.   You choose the 3-plug adapter for up to 3 buildings.  I get that this is easy-to-understand but seems overly simplistic.  In my opinion this was what got them in trouble with their unregulated 4.5V DC adapters but I've beaten that horse in other threads.

Anyway, for about $2-3 shipped on eBay you can get a meter that monitors both the voltage AND current to the buildings.

IIRC member cjack first showed this idea of using this (or similar) digital meter in another lighting thread.  So if you're making a DIY distribution scheme for 4.5V DC to buildings the addition of a current monitor can be handy.  Here's why. 

The current draw of the Menards buildings vary all over the map.  I believe the lowest is the quonset hut which has only 2 (I think) LEDs.  Then you have buildings with over a dozen LEDs, a blinking sign, and maybe a small motor spinning a fan.  Such a building might draw, say,10 times the current of the quonset hut.

By monitoring the current (shown as 0.73 Amps or 730 mA in photo above), you know where you are.  There have been a few data points in some of the other threads but nothing comprehensive.  Woodland Scenics provides guidance for their buildings on number of mA.  Then, since the wall-wart adapter are rated for, say, 1000 mA or 2000 mA you can plan accordingly.

I'm imagining how each Menards building would specify the # of mA so that end-users can plan accordingly.  Or at least someone who has some of these buildings (I don't) could make some measurements to ballpark the mA requirements.  Then you simply count up the number of LEDs, blinking signs, spinning fan motors, and whatever other goodies to get a handle on mA power requirements.

Is that one of the meters that requires an isolated supply for the meter circuitry?

The ones I used worked without an isolated supply for the meter circuitry. But you have to measure at least about 3 vdc for them to work.

The digital meter itself requires 4-30V DC to operate.  Since the load voltage is 4.5V DC, only a single power supply is required.

Needless to say, no instructions or wiring diagrams are provided.

But here's one from a similar meter.

Phssst zzzzzt hic hic    Just joking, but no way I can hook it up without destructions. My two menards buildings have a total of 55 leds and one slowww moving fan. Where do I connect a multimeter to check the draw once I have plugs to test light the buildings?  Or, would that even be helpful?

TedW posted:

Phssst zzzzzt hic hic    Just joking, but no way I can hook it up without destructions. My two menards buildings have a total of 55 leds and one slowww moving fan. Where do I connect a multimeter to check the draw once I have plugs to test light the buildings?  Or, would that even be helpful?

Not sure if you missed the feature of an AC to DC switcher power supply with a Voltmeter-Ammeter attached to it. It answers all the questions and solutions you would have for running 4.5 vdc  buildings and signs on your layout.

Like this...

Guess its obvious I did miss it.  Did you build that?  I'm ignorant of electronics so couldnt build a board like that without detailed instructions.  TW

I don't think cjack built any board.  The board in his photo is just an AC-to-DC buck converter like the one you had.  It's the same board I have in my photo.  About the same price ($5 or so) on eBay but a bit larger since it has screw-terminals for input and output wires and has mounting holes in the corners.

Like setting/confirming the voltage going to your buildings is 4.5V DC, you most surely can simply measure the mA current "once" upon installation to make sure it is not something fishy (excessive).  After all, a permanent meter is probably mounted under the layout anyway!

But I looked up what appears to be your meter and it unfortunately has a limited mA measurement range topping out at 200 mA.  Since you have 55 LEDs and a fan motor, you are probably drawing around 1000 mA which your meter cannot measure.

Your buck converter can handle the 1000 mA no problem so you can just be done with it and move on to your next layout chore.

But if you are the inquisitive type, you can also pick up a FREE (with coupon) digital meter from Harbor Freight Tools that has the ability (range) to measure up to 10,000 mA (10 Amps).  In which case one of us will show you exactly where to hook up the meter to confirm your ducks are in a row...

TedW posted:

Guess its obvious I did miss it.  Did you build that?  I'm ignorant of electronics so couldnt build a board like that without detailed instructions.  TW

That's the same two items shown in STAN2004's post above, but mounted on a plastic 3D printed base. I mounted the first one of those on a wooden piece of paneling, so you don't have to go out and buy a 3D printer. And the wiring diagram is shown in his post as well.

I use these. I have one for each side of the layout. The second one has 7 buildings, 2 incandescent billboards, and 8' of under layout led strip lights. The strips add 500ma. I am using 12vdc for all the buildings, lighting, and signals. 

Hmmm, like you say I'm already half way there.  In for a penny, in for a pound. Could cruise by harbor freight n see what's up, free meter is always good.  

Dang,  John, now we're gettin serious.  

Well, I got the plugs, so all hooked up and the buildings light fine. That depot is bright!  Still having trouble with measuring current. Did I get the wrong meter again?  Txfmr accessory side puts out 12vac and as you can see 4.5vdc on the other end at the buss.  Whats next?

You have the correct voltage on the output.  To measure current, you have to break one of the leads from the module output and insert the meter in series with the connection.  Move the red probe to the fused current jack, set the meter range to 2A range to start and fire it up.

I don't see a 2A range in the photo so you'll need to use the 20A range. 

1. Unscrew and remove the wire connector feeding your strip.

2. Attach Red alligator from meter to the loose wire connector.

3. Attach Black alligator to the vacated strip screw terminal.

4. Move Red meter lead to yellow jack.

5. Change meter mode to 20A DC current.

6. I'm guessing a reading of around 1 Amp with your previously indicated loads.

I couldn't read that in the picture, I thought it was logically a 2A step as it was going up by powers of ten.  In that case, use the yellow 20A jack for the red lead.

Im toast. Still cant get current. Uneducable. Meter always goes to zero. Obviously not hooking probs correctly or wrong dial setting or both.  Thanks for trying. As long as buildings light at  4.5vdc, I'm good.      Buck converters,  Great!

Stan, didn't see your post. So followed that. Pictures!!  Here's what I got. Is that 5900ma?

No, it's 590ma, less than an amp.  1.00 would be 1000 milliamps.

Ta da!

That's 0.59 Amps or 590 mA. 

So if I could ask you to do one more thing.  I see you have 2 buildings connected to the strip. 

If you remove a "red" connector to building A, the meter should then indicate the current to building B.  Then swap procedure to just measure the current to building A.  Obviously the two reading should add up to 0.59 Amps...but if you could document for us the readings for your 2 buildings it will be the first time (AFAIK) that we get some real/documented readings of current into the Menards buildings at the specified 4.5V DC operating voltage.   Oh yes, and tell us # of LEDs in each building and I think one bldg had a fan or something...

Visual learner.   Thx again for the lesson.  Do I change the jacks because the current is so low?  How do I know when to change them in the future?  You all might get tired of telling me each time.  

For measuring DC current, no need to change the meter jacks for this application.  If the current is really really low, like under 0.2 Amps, then you could/would but I don't think that's the case here.  Note that your readings are showing 2 digits of resolution or 0.xx Amps which is good enough for the matter at hand. 

Yes, we can get into a nerdy discussion about accuracy vs. precision vs. resolution vs. who-gives-a-rip

Ok, so now I'm starting to show off.  Farm Supply, 7 led and fan motor .08A, Depot, 48 led, .51A.  Total .60A!  Whuuut?    .59A most of the time!!

By jove, I think he's got it!

So, in round numbers, each LED is drawing about 10mA (0.01 Amps).  And the tiny fan motor about the same.  

The idea of course is the current measurements allow you to manage your building lights ... knowing where you stand.  Yes, it's more work/bother than using the 1-plug (1000 mA) adapter for 1 building and the 3-plug (2000 mA) adapter for up to 3 buildings but to each his own.

Probably, I should just move on to building boards and arduino coding.  Thx, John and Stan for the lessons. I really appreciate your patience, time and trouble. TW

Sorry I posted this on the wrong topic...............Paul

paul 2 posted:

Sorry I posted this on the wrong topic...............Paul

You can delete your own posts.

Thanks GUNRUNNERJOHN, I learn something new each day........Paul