Small Mod help - Electrical

Hi All,

I was at my local Ikea yesterday and found they where having a clearout on these little battery powered lights (Name on the box is GLÄNSA).

I want to try and mod it for use on my PC, but I’m not that good at electrics.

It uses 2 AA Batteries, it has a transformer that steps down the voltage to about 30 milliamps.

Things I need to know, Will DC work with it, how can I get the 30 milliamps from a molex connector?

Any help will be great thanks.

Apologies if this is the wrong section.

You'll need to take the voltage off of a +3.3V line. That's the orange as positive and black as negative. I think they've got one on the floppy connectors, but I'm sure you'll find one to get the power off of. You'll want to keep the circuit and just solder the + end of the 3.3 to the + end of the battery terminal and the - end to the negative end and then complete the circuit by bridging both ends of the battery holder together and you should be set

what mrps2 said is correct. 3.3v should be fine.

i had a look for them on Google and they're EL wire, not lights

My mistake, So it's ok to use DC on them. I will keep the circuit board, as it has a switch to change between flashing to constant.

Not bad for £2 tho.

Also, i just had a quick look, and couldn't see any cables that are orange, other than the 20 pin on for mobo. It must be hiding.

Yeah, I'm sorry bout that, but floppy connector's definately don't have 3.3V... If your PSU is a little older, you might have an AT boar power connector, I'm 99% sure those do actually have +3.3V on them. Otherwise, as you said, the ATX connector will probably be your only choice. It won't be too bad because you can sorta tie a wire around the existing top end where the wire already comes out from and be fine, but it may not end up looking as clean as it could... Anyways, cable routing is fun anyways, just make sure the wire you use is cut to the right length

Just thought i'd check, is the red wire on a molex 5v and ground to the first black next to the red.

Also, is EL wire realitivly cool, i dont want it catching on fire.

thanks.

Personally, I feel nervous messing around with the 3.3v feed to the motherboard. If I were doing this mod, I'd take one of those spare drive connectors and build a voltage divider/current limiter to tap off teh 5v rail.

Let's see... at 3vdc and 30ma current max, the impedance of the wire is around 100 ohms-- conveniently round number.

We need a divider circuit that will provide no more than 30ma, so easiest way to calculate would be to make the 3v branch resistor equal to the anticipated impedance of 100 ohms.

That means that total current through the divider circuit can be 60ma, and therefore total circuit resistance is 83.3 ohms. Round up to get slightly below max allowable current.

Get a 100 and a 34 ohm resistor, both .5w or better, put them in series. Feed your EL wire across teh 100 ohm resistor and you should be golden.



For the mathematicians:

I=E/R <-- Ohm's Law
P=IE <-- Power formula

Where:
I= current in amps
E= Voltage in volts
R= Impedance (resistance) in ohms
P= Power in watts

Dngrsone's way will work, personally i don't see much problem with adding a little extra load onto the 3.3v line, but there you go .

no, EL wire doesn't get hot.

Well, do bear in mind that I did mod the standard Enermax PSU fan into an LED fan and soldered the LEDs directly onto the main 3.3V line on the PCB. lol So yeah, Dngr's way is safer, but both methods will work so long as you're careful, though I don't see any risks associated with taking voltage off of the 3.3V line, it's pretty much exactly the same as the 5V, other than the fact that it's the ideal voltage and you're getting it from another connector...

I used an old Molex connector from a fan, soldered it on and it works perfect, I had to swtich the pins around to use 5v tho.

Glad to hear it worked out for you. Post a pic.

Will try to get a pic, I havn't installed it atm, looking for a good way to fix it the acrylic window.