Recommendation for voltage adjustable buck convertor?

Here's one good for a couple of amps out, $6.39 on Amazon.

Mini AC/DC to DC Buck Step Down Module

For what you want to do you need an AC-DC converter.  You can find them on both Amazon and E bay.  Look for one which is adjustable and the input range has to be more than output.   I like to use  those with a built in volt meter but they can also be added.  As far as which to buy I cannot recommend one seller.

Marty

Given that you're going to adjust the voltage one time, I can't see spending extra money for a meter on the module.

Thank you all for the quick responses,  I've ordered the one that John recommended from Amazon.  I know these probably aren't made in the US.  My issue with China is that I just don't like sending my credit card information there.

Wehonest used to sell them for like 1.59 without the meter. It was DC/DC so you needed to add a rectifier in the input circuit.

@lionelflyer posted:

Thank you all for the quick responses,  I've ordered the one that John recommended from Amazon.  I know these probably aren't made in the US.  My issue with China is that I just don't like sending my credit card information there.

Fair enough. FYI when you purchase on ebay, the seller doesn't get your CC info. They only see the funds added into their account.

And if you look closely at Amazon. You'll see that all of the sellers are from China as well

@gunrunnerjohn posted:

Here's one good for a couple of amps out, $6.39 on Amazon.

Mini AC/DC to DC Buck Step Down Module

Don't plug it into the wall outlet like this reviewer did .

"Don't use 120 volts AC as I did, it went boom in my hand, read the fine print 50 vac max. I was looking for a 120vac to DC converter but little did I know it was only rated at 50 VAC input, i went back to the multiple photos and found after the fact the small part that read 50 volts AC max input "

You may find that rotating the adjustment screw CW lowers the output voltage on that particular model.  Also, if not familiar with these converters, the adjustment screw has a range of maybe 20 or 30 turns.  You might wonder if it's broken when it only slightly changes voltage with a 1/2 turn or whatever.  There is no hard/mechanical limit when the adjustment reaches the end of travel in either direction; there is a clever releasing ratchet-like mechanism to keep the voltage at the max or min setting if you continue turning beyond the end.

For 99.9% of applications this is a one-and-done voltage setting so the CW vs. CCW behavior is a non-issue.  OTOH if this is an issue, de-solder the blue trimpot and rotate it 180 and then CW raises the voltage.  And if you're removing the trimpot, consider a long-knob version which allows you to finger-adjust the output voltage without a tiny jeweler's screwdriver!

I could see where plugging a unit rated for 50V into 120V might not be good for your health (or heart!).  I'm only going to attach it to a ZW that, at most, can put out 20V.  I'll then run the wires out about 20 feet to a distribution terminal and feed the Menard's buildings from there.  At least that's the plan flapping around in my head.

@stan2004 posted:

You may find that rotating the adjustment screw CW lowers the output voltage on that particular model.

The Chinese apparently still haven't mastered western conventions regarding voltage adjustments.

lionelflyer: Some of the Menards buildings will use a good deal of current. Note that a buck converter like the one recommended here will drive a maximum of 2.2 amps or 2200 mA. In continuous use, I'd expect somewhere around 1500 mA. So you may want to get several of these and tie them in farther down the line; closer to the distribution terminal.

I'd do it this way. Run the AC line from your transformer out to a terminal block. Then add the buck converters from there to a secondary terminal block that will distribute the power to some of your buildings. If you find that another building causes the converter to fail, then you can add another converter in the same way off of the AC terminal and start a new distribution terminal. This will give you some room for expansion.

Consolidated Leo: Excellent suggestions.  By your suggestion, I went back and looked at some of the buildings and they can draw a lot of current.  I'm not sure now if the ZW will even have enough power since I wanted to also use that for street lamps and other accessories.

I do have two 180 Watt power bricks but I probably need some way to deliver the power from them.  I have a ZW-C but it shorts out when the A throttle is applied. I had a shop look at it and they seem to think the main board is faulty.  The other throttles seem to work okay.  I should probably wait on all of this until next week when my son comes home for Christmas.  He is an electrical engineer, although he works mostly in robotic controls so it's a lot of software integration with hardware and not circuit design.

@lionelflyer posted:

...

I should probably wait on all of this until next week when my son comes home for Christmas.  He is an electrical engineer, although he works mostly in robotic controls so it's a lot of software integration with hardware and not circuit design.

This being a discussion forum, here's a different tack.  Use a DC bus.

If you're going to add a new transformer to supply Menards power, an alternative is to start with a DC-output brick.  Of course you may already have unused ZW AC-output sources so your out of pocket is $0.  But $-for-$, pound-for-pound, Watt-for-Watt, etc. you get a superior bang for the buck with DC-output vs. AC-output at the power levels we're talking about.

Above is a 12V DC, 5A DC (12V x 5A = 60 Watts) brick for about 15 cents per Watt.   If starting from DC, you can get DC-to-DC converter with adjustable DC output for less than $3 each when you buy 6 as shown above.  Each of these modules also contains an integral digital voltmeter!  You can get DC-to-DC converters without the integral digital voltmeter for even less.  These modules put out about the same ~2 Amps as the AC-to-DC module you purchased.  That is, if set to about 4.5V DC (for Menards buildings) and around 2 Amps, that is about 10 Watts per module (4.5V x 2A = 9 Watts).

Technology being what it is, for the power levels we're talking about, a DC-output brick is far more efficient, inexpensive, compact, etc. than a traditional AC-output brick.  Here's a photo I've frequently posted contrasting a 90 Watt DC-output brick with a 100 Watt AC-output MTH Z-1000 brick.

A simple metric I use is to spend about 10 cents per Watt to get low-voltage power from a household 120V AC wall-outlet.  I guarantee that you will not be able to buy a Z-1000 100 Watt brick for $10...whereas I've purchased many 90 Watt DC bricks for $10 delivered to my door!

Anyway, so from a system wiring perspective here's the comparison:

I show 3 modules by way of example.  You may have more or less depending on the Wattage needs of your real-estate portfolio.  If you review old OGR threads about Menards buildings, you will find many examples where the voltage is fine-tuned.  Some buildings may be set to the nominal 4.5V DC, but it seems most guys set the voltage to something lower - maybe 4.2V, 4.0V, etc.  So at minimum different buildings can be grouped by voltage with different modules set to different voltages.  This applies to either method.

Where your son can "give back" to dear-old-dad is some of the finer points about the AC vs. DC bus method.  If he's into robotics, he will surely understand the issues with distributed power especially with regard to power efficiency...  Watts-in vs. Watts-out and minimizing heat loss.

He'll surely recognize that with the AC method (and multiple AC-to-DC converter modules) there is no DC common in the system.  In the DC method the minus (DC-) side is common throughout.  In the AC method each module has a distinct/separate DC-.   He will surely point out that with the DC method, you can even have an AC-DC common (DC- can be tied to AC common) which can be put to advantage.

But to be clear, your present direction of using one or more AC-to-DC modules powered by a ZW's AC-output will work!  Again, this is a discussion forum; as I see it, with modern electronics which includes how "DC" LEDs have supplanted "AC" incandescent bulbs in building lights...there is a school of thought that the sooner your wall-outlet AC power is converted to DC power the better!

https://www.aliexpress.com/ite...&ck=in_edm_other