Building a 4.5v Power Supply for multiple leds and hobby buildings

Thread Starter

craynerd

Joined Nov 20, 2020
4
My wife has gone a bit mad this year buying these Lemax Christmas buildings, the little villages that light up. She must have about 8 houses along with another 8 plug-in moving items.
The brand do their own power supply... 4.5v with 3 connectors to plug into three devices at a whopping £20 each. We are going to need about 4 or 5 of these and the wires are a mess.

0BD9A0E3-6EB5-4CCE-8AD8-48D658E6D869.jpeg

what would be the best way about making a multi plug adaptor so we could just plug all Of them in to one block?

I am competent at following electronics and have built many electronics projects but I don’t pretend to be a great designer and could do with some help. Am I right in thinking that if I can source a suitable power supply, these LEDS houses only draw about between 62mA and 200mA so I can have as many devices connected as I want provided I don’t exceed the maximum current of the supply?

I can easily source a high current 5v supply how could I drop this to 4.5v?

Any help appreciated.
Chris
 

dl324

Joined Mar 30, 2015
12,873
Welcome to AAC!

Have you tried powering the things from a 5V power supply?

Places that sell security cameras sell splitters that let you connect up to 8 devices to the same power brick. Wiring is going to be a bigger issue.

EDIT: Here's one from Walmart:
clipimage.jpg
 

djsfantasi

Joined Apr 11, 2010
7,700
First, the LEDs may work fine on 5V. Try running one and measure the current draw. Compare to the listed current for the lighting modules.

Or second, put a diode in series with the power supply per module. I’m not sure of that (one per module.) Diodes typically drop 0.6-0.7 volts independent of the current. That would give you 4.3-4.4V. A safer value.
 

Thread Starter

craynerd

Joined Nov 20, 2020
4
First, the LEDs may work fine on 5V. Try running one and measure the current draw. Compare to the listed current for the lighting modules.

Or second, put a diode in series with the power supply per module. I’m not sure of that (one per module.) Diodes typically drop 0.6-0.7 volts independent of the current. That would give you 4.3-4.4V. A safer value.
Ok thank you. This is where my knowledge lets me down. So yes, I’m happy with your idea and fully understand it But say I did buy A standard off the shelf 5v 5a dc supply, what diode exactly would I be needing?
 

Thread Starter

craynerd

Joined Nov 20, 2020
4
Welcome to AAC!

Have you tried powering the things from a 5V power supply?

Places that sell security cameras sell splitters that let you connect up to 8 devices to the same power brick. Wiring is going to be a bigger issue.

EDIT: Here's one from Walmart:
View attachment 222913
lol, thank you for your reply.... but then I wont have a making and building project lol nice idea man, thank you.
 

djsfantasi

Joined Apr 11, 2010
7,700
If you use one diode per module, I’d select one rated for 500mA. Otherwise, I’d multiply 200 x n (number of modules) and use that for the rating.

Diodes aren’t expensive. I’d go with one per lighting module.
 

dl324

Joined Mar 30, 2015
12,873
but then I wont have a making and building project lol nice idea man
If it were me, I'd run some zip cord (16AWG lamp wire) by the lights and tap into it as needed. They make automotive connectors that just clamp on the wire, piercing the insulation to make contact.

EDIT: something like this:
clipimage.jpg
If you can't find some that take lamp cord gauge, use a thinner wire. I suggested lamp cord because it will blend in better than your typical black insulation.
 

djsfantasi

Joined Apr 11, 2010
7,700
One that will handle 5V . Before you go that route, see if the things will run on 5V.
You are mixing up solutions. The diode is used to drop the voltage below 5V, so the question is (correctly) do the lighting modules / LEDs run with 4.3-4.4V

Update: corrected 5A to be 5V. @dl324 pointed out my error.
 
Last edited:

dl324

Joined Mar 30, 2015
12,873
You are mixing up solutions. The diode is used to drop the voltage below 5A, so the question is (correctly) do the lighting modules / LEDs run with 4.3-4.4V
How do you figure?

He's going to use a 5A supply and I suggested a 5A diode so he only needed one.
 

AnalogKid

Joined Aug 1, 2013
9,261
What is the output rating of the supply in post#1? Its current rating (divided by 3) will tell us the expected worst-case current for any attached device.

ak
 

djsfantasi

Joined Apr 11, 2010
7,700
How do you figure?

He's going to use a 5A supply and I suggested a 5A diode so he only needed one.
Ok, he’s using a 5V supply and a diode to drop 0.6-0.7V. The modules are rated to run on 4.5V, so he should check to see if they run on 5V (without a diode) or 4.3-4.4V (with a diode), Depending on the solution he chooses.

The diode current rating is a separate issue. Please don’t confuse him.

Update: I may be the source of confusion. I typed 5A instead of 5V. Check my corrected post.
 

Thread Starter

craynerd

Joined Nov 20, 2020
4
What is the output rating of the supply in post#1? Its current rating (divided by 3) will tell us the expected worst-case current for any attached device.

ak
It’s 4.5v 1A
so I presume they are allowing for 0.33A per connection. One connection we run is 4 LED modules to light up four houses and that only plugs into one of the inputs so they are really small draws.
 

dl324

Joined Mar 30, 2015
12,873
It’s 4.5v 1A
so I presume they are allowing for 0.33A per connection. One connection we run is 4 LED modules to light up four houses and that only plugs into one of the inputs so they are really small draws.
You need to determine if the devices will operate from 5V. One way to do that is to is to open up one of them to see how the LEDs are wired. Another is to plug them in to a current limited 5V supply and see if it goes into current limiting. Or you can just go for broke and connect to 5V.
 

Wolframore

Joined Jan 21, 2019
2,283
The 4.5v convention comes from using 3 AA batteries. In fact some of them have battery compartments built in. They should work fine to under 4V.

5V with a schottky diode sounds ok, Vfd goes up with current... maybe dividing them diode per branch would reduce drop and heat. It’s over 3 watts at 0.7 with 5A. Even if we got it down to 0.3 it’s nontrivial.

You can source 4.5V 2A switching supplies. Just add one of those distribution with the 3.5mm plugs or make your own. Just wire them parallel.

White wires hide better in that fake snow

We’ve been collecting for a couple years and just keep adding power strips. I did find a 1 to 5 plug adapter and just found out it works. I haven’t checked the current draw, they appear to vary... some have motors and other circuits. Others are just some pretty LED’s. Some get very elaborate and have up to 50 LED’s with sequencing and music.
 
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