Help with electronics please!

[Chris1712]

Hey guys, I'm a bit bored at the moment so i've spawned a mini (very) project to give me something to think about.

The plan is, to get 2xDual cold cathode kits, sound sensitive and mount on the back of my floorstanding speakers, just to give some cool effects when im partying!

I've found a few AC Ryan and Akasa sets still available, and im just thinking about wiring them up.

The AC Ryan specs are.....
# Voltage : 570 ± 40V
# Current : 3.5 mA

So thats ~2w each tube (P=VI), the inverter supplied takes 12v from a molex and chucks 5ma down each output (two of em). Because I'll be powering these obviously not from a pc but from mains i'm trying to figure out what kind of psu i'll need. How much amperage will the inverter be taking? Is it as simple as 5ma x the two outputs = 10ma?

12v obviously, but what kind of amperage? Looking around i spot them anywhere up to about 2A before you start getting bigger power bricks but i doubt I'm going to need that much juice.

What am i missing here guys? Sorry I'm a bit of an electronics n00b (even though i did electrical engineering for a year.....).

Also, finding out polarity on the 12v tip, the plan is to just snip/solder to a molex.

Cheers for any help guys!

Chris1712.

 

[Flukester]

Hi

Well if the tubes are 2w the I guess approx 166mA per tube, so 330mA total...plus a little for the invertor circuit I guess as they are not 100% efficient. (2/12 = 0.166)

Get a little switch mode PSU, a 1A one will be cheap and small...and plenty enough without worrying about the maths

If the invertor has standard 4 pin molex then one of the center two pins will be ground, the outer 12v (on a PC molex they are +12v 0v 0v +5v)

To find the polarity you need a meter, but generally the +v wire will have a white stripe on (and wired to tip of PSU power connector) ...


Take the above with pinch of salt as I'm rusty on electronics...

 

[Chris1712]

Hi

Well if the tubes are 2w the I guess approx 166mA per tube, so 330mA total...plus a little for the invertor circuit I guess as they are not 100% efficient. (2/12 = 0.166)

Get a little switch mode PSU, a 1A one will be cheap and small...and plenty enough without worrying about the maths

If the invertor has standard 4 pin molex then one of the center two pins will be ground, the outer 12v (on a PC molex they are +12v 0v 0v +5v)

To find the polarity you need a meter, but generally the +v wire will have a white stripe on (and wired to tip of PSU power connector) ...


Take the above with pinch of salt as I'm rusty on electronics...

Yup that makes sense to me and adds up about right to what i was expecting. Is the polarity on the DC 12v pin standard? I mean on the new psu not the molex, ie centre ground outer ring 12v?

 

[Flukester]

it's usually outer ring 0v and tip is +v ...but some PSUs they give you reversable tips.

you'll prolly cut connector off the PSU and wire staught to the invertor wires, and I'd say 95% chance the wire with white stripe on will be +v

if you lucky then the PSU will have a screened wire instead rather than twin wire, which is 1000% sure to have +v on the inside and 0v as the screen.... (as this 0v screen protects the 12v wire from electrical noise)

it's always best to check with meter though...saves unwanted explosions