AC external Xmas lights

Thread Starter

pmslater

Joined Oct 25, 2020
12
If this was in a controlled environment I would have no issue. Its not an option I am prepared to entertain (I even have a 230v inverter I could use) especially now I have a possible solution.

Is that a local law? The inverter is completely contained and with the power supply plugged in I don't see any danger.
 

Thread Starter

pmslater

Joined Oct 25, 2020
12
See post 14,

Crude but but in theory works.

One solution is to use a L298 bi-directional motor driver module like the unit shown below controlled by a LM555 astable.
 

Thread Starter

pmslater

Joined Oct 25, 2020
12
I'll get it going with an Arduino, but might buy the parts to make the LM555, however, I like the idea of using the Arduino to make the lights flash tweaking the frequency and maybe even a timer so they go off @ night. All crude but a nice project.
 

Yrless22

Joined Sep 7, 2011
4
hi pm,
This type of module will step up from 12Vdc to higher voltage, but the 12Vdc source will have to be capable of supply the current for the converter.
Do you have a link to the Fairy light sellers web page.?

E
https://www.ebay.co.uk/sch/i.html?_...7.m570.l1313&_nkw=12V+step+converter&_sacat=0
I've done something similar to this few times but it involves opening the case of the power/control module (AC supply/controller) it also usually mean loss of pushbutton function, but here goes:
Carefully split the case of the power/control unit using hacksaw, knife blade, etc. Once open clean out the silicone or other materials so you have access to the ckt board. One end of the board is the AC input side and the other is the PWM output side. In between should be a transformer that steps down the voltage and applied it to a rectifier ckt. Carefully unsolder the transformer and remove it. Check the pads where the secondary was connected. One side should pass through some surface mount diodes and then on to a fairly large capacitor. Mind the capacitor polarity and apply your 30V DC across the cap. (I've also just applied the 30V to the secondary pads). This remove all of the higher voltage components on the primary side from the circuit and all you are left with are the LED drivers and the pattern generator. If you don't already have a convenient 30V source there are plenty of buck converters available dirt cheap. You may be able to salvage the pushbutton program selector feature but I don't think this is likely.
 

Thread Starter

pmslater

Joined Oct 25, 2020
12
And you would expect the AC output to be maintained,

Suppose it all depends how its designed. I always assumed it used the existing AC but that wouldn't work for the various programmes /LED Patterns. Good idea,
THANK YOU!


I've done something similar to this few times but it involves opening the case of the power/control module (AC supply/controller) it also usually mean loss of pushbutton function, but here goes:
Carefully split the case of the power/control unit using hacksaw, knife blade, etc. Once open clean out the silicone or other materials so you have access to the ckt board. One end of the board is the AC input side and the other is the PWM output side. In between should be a transformer that steps down the voltage and applied it to a rectifier ckt. Carefully unsolder the transformer and remove it. Check the pads where the secondary was connected. One side should pass through some surface mount diodes and then on to a fairly large capacitor. Mind the capacitor polarity and apply your 30V DC across the cap. (I've also just applied the 30V to the secondary pads). This remove all of the higher voltage components on the primary side from the circuit and all you are left with are the LED drivers and the pattern generator. If you don't already have a convenient 30V source there are plenty of buck converters available dirt cheap. You may be able to salvage the pushbutton program selector feature but I don't think this is likely.
 
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