Electronics > Beginners
Hooking up 4 x 3v LED string lights to a 6v PSU
bob21:
Hi,
This is a total n00b question, and one which I am sure has probably been answered but I am not exactly sure what it is that I am searching for, so searches turned up a lot of results that didn't seem to fit.
So here goes:
I have 3 x cheapo LED string lights. The kind you get from bargain stores that run on 2 x AA cells, so totaling ~3v DC per set. Like this: https://imgur.com/a/CrOQbYI
I want to hook all 3 of these up to a PSU I have here that is 9v DC. So the question is: can I just splice all 3 together and connect to the PSU? Or is this the worst idea ever?
My logical head says the load will just balance and each string of LEDs 'should' get its required ~3v. But then I wouldn't be posting this question if I wasn't totally sure it wouldn't catch fire to the house, cat and everything in the vicinity :-//
Will this work? If not, what is the best way to go about this? If I need to grab some components and solder something, I can do this. But I wouldn't have a clue what I would need to buy and solder to what.
Any input would be very much appreciated
Edit: Changed title to reflect current aims.
TerminalJack505:
Are there some components other than the switch in the base? I can't tell from your picture. It is likely that there is some type of boost circuit in there, such as a Joule thief. How you proceed will depend on what type of circuit is being used to drive the LEDs.
tunk:
Looks very much like a LED string I have and there's no electronics inside.
If it's 9Vdc +/-0.1V, then in principle it should work if you connect the
three strings in series, i.e. 3+3+3V. As a precaution you could add a low
value resistor in series, maybe 5-10ohm.
Zero999:
Those LED strings rely on the internal resistance of the batteries and LEDs to limit the current.
What voltage does the 9V power supply actually measure, when you connect a meter to it?
bob21:
Thanks all for the swift responses!
--- Quote from: TerminalJack505 on February 01, 2020, 06:46:45 pm ---Are there some components other than the switch in the base? I can't tell from your picture.
--- End quote ---
The picture I linked to was just an example. I have checked the 3 lights I am using, and they seem to be just a switch between the cells and the string. Like tunk's. They are cheapo units from B&M, Home Bargains, Poundland etc.
--- Quote from: tunk on February 01, 2020, 07:00:43 pm ---Looks very much like a LED string I have and there's no electronics inside.
If it's 9Vdc +/-0.1V, then in principle it should work if you connect the
three strings in series, i.e. 3+3+3V. As a precaution you could add a low
value resistor in series, maybe 5-10ohm.
--- End quote ---
Series isn't possible, the lights move away from each other in different directions. Sorry I should have mentioned this a bit better. All battery units are within a few cm of each other, but the other end of each string is not. It's a bit like this: https://www.dummies.com/wp-content/uploads/312189.image0.jpg
Is there no hope of a parallel connection? I have small ABS boxes that can house some components if needed. Basically, the whole idea of this is that the lot is plugged into a smart plug at the end. It's a bind turning on and off each lot every time I use them. I want to just ask Alexa to do it instead and they chew cells if I leave them on too.
--- Quote from: Zero999 on February 01, 2020, 07:43:35 pm ---Those LED strings rely on the internal resistance of the batteries and LEDs to limit the current.
What voltage does the 9V power supply actually measure, when you connect a meter to it?
--- End quote ---
I hoard old PSUs so I have some choice. I've just checked the 9V PSU I originally mentioned and it's reading at: 8.9v and is supposedly 1.7A. Please note my meter is a cheapo and not a nice Fluke as I would like one day ;)
I have others that may be better suited, these are all the others below 12V:
6V~300mA x 2
8V~400mA
5V~1A
4.5V~1A
6V~800mA
5V~800mA
Navigation
[0] Message Index
[#] Next page
Go to full version