Model Railway Forum

hi would it be safe to use old mobile phone chargers to power led street lamps on my layout with voltage resistors fitted to lower the output of the chargers from 9volts regards bob

Hi
No problem with old phone chargers being used. Many today are 5 volt, older ones can be 8-9volts. Do ensure you have a series resistor fitted per LED lamp.
Phone charges tend to have a smaller current output typically 200 to 500 milliamp so cannot feed many LEDs as a larger 12 volt 1.0Amp or more power supply can, but you will still be able to feed around 10 to 20 LEDs all lit depending on power supply rating.
Work on each lit LED will draw 0.02Amp (20 milliamp) and add them up.

Do allow an overhead of at least 10% so as not to stress the power supply by running it at maximum current all the time.

Richard

thanks for the fast replys i have started to wire in the lamps each fitted with a resistor fitted to each one and they look great i have a few old chargers so i can spread them out and share the load without overloading one particular charger thanks again bob clifford

Always a good idea to add a fuse system to these power supplies. Not sure how they behave if they are shorted out

I know I’ve said this before but this is my preferred method for ‘safe’ power supplies for lights etc.
I bought a cctv PSU rated at 12v dc and 8 amps. The PSU was supplied eight-way splitter originally to feed eight cameras.
I fitted each feed with a self resetting 1 amp fuse effectively limiting each feed to a ‘safe’ output.
Each separate 1 amp supply feeds a cluster of lights that together draw less than 1 amp.
Admittedly I did mine about five years ago but I think the overall cost was less than a tanner.

Wow - less than 2 1/2 pence! Or do you mean a Tenner

IanS wrote: ↑Tue Jun 02, 2020 9:31 am Wow - less than 2 1/2 pence! Or do you mean a Tenner

I did, but autocorrect thinks it can do it cheaper!
Either way, its cheap and most importantly, safe.