Wiring Advice needed [Solved]

[stigzler]

Hi Folks, need some advice on wiring. Two PSUs in my cab. Looking to wire up some LED strips. Diagram (obv red=live, black=com/ground):



Two questions:

A) Does it matter how I run the live feed to the strips. Embarrassing, as GCSE physics stuff! Will it make a difference whether I wire in parallel (Opt B) or in series (Opt A)?? Will it effect the brightness of the LED strips? (seem to remember two bulbs wired in series are half as bright compared to two in parallel?)

B) Does it matter that the grounds will be returning via the PC PSU rather than the 'originator' PSU?

Cheers folks and hope you can help (I'm gonna have nightmares about wires tonight having spent all day wiring!)

[DaOld Man]

If each strip is rated for 12 volts, you need to wire them in parallel.
The ground (negative or common), from the strips needs to go back to the power supply feeding the strips.
It is ok to tie the two power supplys grounds together, if you need to for the pac drive.

Im not familiar with the pac drive, but if it offers a separate ground for the leds, you need to tie it to the big power supply.
What you have drawn will not work, because there has to be a ground from the 50 a psu tying to the led strips.
Also, the usb port is only good for no more than 500 ma (1/2 amp), so you don't want to power the led strips from it.

[stigzler]

Hey. Thanks for the reply DaOld Man. It sounds like really bad news on first impressions. The pac-drive works thus:



You can see that any LEDs or LED strips are controlled via the grounds. It does say here that it can return more than 0.5A to ground through the USB shielding.

Thus - I'm wondering if when you talk about a 0.5A limit are you meaning as a supply voltage?

Secondly, I emailed Andy from Ultimarc some time ago who very helpfully replied:

Steve,

Yes that would be fine. The grounds would need to go back to the PC casing.

The board will switch up to 0.5 amps per output. We will shortly have some driver modules which will handle 4 amps which can be added.

Regards

Andy

-----Original Message-----

Subject: HI - Pad-Drive Question

Hello there,

I recently purchased a Pac-Drive from you. I'm looking to run both 12V and 5V leds off it - is that possible? Both 12V and 5V supplies would be external (an external PSU) - so would just be running grounds to it as I understand it. So, can I run grounds off boht the 12V arrays and the 5V Leds onto the same board?

Lastly - the 12V feeds are going to supply separate LED strips (daisy-chained leds)- is there any limit on the Amps that can run through the board?

Many thanks + thanks for great products!

Steve

The 0.5A per switching is no problem, as max A will be 0.3A as per diagram below (there's some connections missing, but to illustrate Amps involved):



But now I'm confused when he talks about grounds going back to the PC casing!

This is all really confusing!!

In terms of tying the two PSU grounds together - wouldn't this be the case anyway as they both plug into the same power strip in the machine? I'm going diagram crazy tonight, so for illustration:



I do hope this doesn't come across as pedantic or being difficult. I'm just trying to understand this setup and hoping that I can run any lighting off the separate PSU rather than put a drain on the PC one! This feels like one of those things where it's unwise to just "try it and see"!! I keep joking to people that I'm gonna keep a fire extinguisher next to my cab, but seriously considering now!

I hope someone can help and sorry if the above is a little unclear. Cheers for people's ongoing help.

[stigzler]

I really do hate to bump my own thread + realize this makes me  's spawn.

However - really struggling with this one - please - there must be someone with good 'tronics knowledge who can advise/help out?

eeepp - soz >.< but cummaaan.. i need this!

[stigzler]

OK solved with advice from Ultimarc.

I think Da Old man this is what you were saying, but just couldn't make it work in my head.

Basically, you solder a ground wire to the mini-pac usb socket lugs (+ground) and return that to the 50A PSU. Lugs here:



Hence ground returning to both PCs: one via this new connection and the other via the usb.