Anyone with electronics knowledge - Will this work?

[jolly_tas]

I have bought a display cabinet to put 1/18th scale dicast models in and want to light it with LED light bars.

I figure I would need a 100ohm resistor per bar and can go to a maximum total of 40 LED's (8 per shelf) to stay under 850mA current draw.

What I am wondering is if I wire the LED's up as shown, will it work? I am planning on using an old phone charger (output of 5V and 850mA) as the power supply.

Any information in regards to this would be appreciated.

And sorry if I have posted it in the wrong area.

Cheers.

[Blakey]

it wont work, to many led,s in series you have 5V and over 15V in voltage drop. either more Volts or less leds

with a 5V source voltage you can only have 1 LED on each line.

[jolly_tas]

If i did in in parallel would it work or just buy a power pack that would put out 25v??

[Blakey]

to have 40 LED's with a source of 5V then you will need 40 parallel single LED's using 2640mW for the led's and 1600mW for the 100 Ohm resistors BTW that uses .32A or 320mA


if you get a power pack of 25V then you can do a
5 x 8 (5 parallel by 8 in series on each line) array uses 40 LEDs exactly using 470 ohm resistors
4144 mW or 165mA i think i may be converting these wrong lol. im not good with conversion from mili to normal

[Blakey]

also you can do about 300 Led's before you get to anywhere near 800mA

Ooo so close 300LED's with a 25V source is 792mA

[jolly_tas]

Cool. Thankyou very much for your help. Will see if I can work out the wiring by doing it parallel, that way I can have more LED's for better light. Could be a lot of mucking about tho. May be easier to stay with the 5x8 LED set up and get a larger power source. Cheers.

[Blakey]

if you dont want to get a larger voltage input, to do the parallel just connect all the + of your LED's Together and all the - together, with wires,


like this but 40 of them all + connected all - connected

+----|>|---/\/\/----|- R = 100 ohms
+----|>|---/\/\/----|- R = 100 ohms
+----|>|---/\/\/----|- R = 100 ohms
+----|>|---/\/\/----|- R = 100 ohms
+----|>|---/\/\/----|- R = 100 ohms

[jolly_tas]

Am searching for an easy way to do it now... lmao! Thanks for your help

[Blakey]

Am searching for an easy way to do it now... lmao! Thanks for your help

just get a piece of steel ridged wire but not to thick, place 2 lines of that where you want your LED's to go so like a big track of it. then connect your resistors and leds to the 2 tracks, then connect your 5V source to both of the wires one positive and one negative. done simple busbar, for it all. is only 5V if your worried about having live wires then get some eletrical tape and tape over the wires. if the shelving's are wood if metal then probably best to use insulated wires and cut the insulation off where you need then insulate again with heat shrink or electrical tape.

[Blakey]

i can draw you an example if you want.

[jolly_tas]

I think I have the idea. Just strip the main wire where I want the resistors and LED's, and connect one wire to the + and the other to the -. Just make sure all the LED's polarity's are correct and insulate the connections. Should all be sweet!

[Blakey]

yep, for polarity you can check what leg is longer the anode + is longer then the cathod -

heres a pic to help

[jamez707]

good work blakey +1. i just discovered this thread im glad i didn't have to explain all that...good luck jolly_tas take a photo when you are done and give us a look

[jolly_tas]

ok... this should work... hopefully! lol

[Blakey]

yes i believe that should work. i confused myself when i first looked at it, but yes it seems good.