Cold Cathode Power Supply

Hi all,

I'm new here and hope you can help.

I'm planning on using 16 Cold Cathodes (8 inverters - 2 cathodes of each inverter, from ebuyer.com) to light an area in a kitchen.

To power them, i need a 12vDC supply. i've thought that a scalextric power supply would be ideal, however when i tested one last night, the inverter blew after about 10minutes. Everything looked find until then.

I only had on cathode plugged in to the inverter though, would this be the reason? or do i need some kind of resistor or capacitor before the inverter? Are there any tests i can do to check voltage etc?

This is probably a real easy one for you guys but i don't want to risk plugging all 16 cathodes in to find that they blow within 10minutes.

Any help appreciated.

You need a 12V power supply, a Scalextrix supply isn't that!, buy a proper supply.

What are the current requirements?.

Nigel Goodwin said:

You need a 12V power supply, a Scalextrix supply isn't that!, buy a proper supply.

What are the current requirements?.

Click to expand...

I don't know where to find the current requirements (apologies). I thought a scalextric power supply was 12 - 13.8v, are cold cathodes that picky about 1.8v? if so could i caluculate a resistor value somehow?

If i put extra load on the power supply (ie by using 8 inverters, 16 cathodes) would the output voltage drop or rise?

chriselias272 said:

I don't know where to find the current requirements (apologies). I thought a scalextric power supply was 12 - 13.8v, are cold cathodes that picky about 1.8v? if so could i caluculate a resistor value somehow?

Click to expand...

A Scalextric supply is only rectified AC, it's not suitable for powering electronics at all - it's just a transformer and a rectifier. It has the potential for being made into a power supply, but may not be suitable for as high as 12V after regulation.

As it stands it's probably outputing pulses far higher than 12V.

If i put extra load on the power supply (ie by using 8 inverters, 16 cathodes) would the output voltage drop or rise?

Click to expand...

It will fall, but still won't work - get a proper power supply!. But in any case, you HAVE to know the current you need, you're just going to blow one that's too small!.

Thanks so much for your replies.

I think i'll be trying to obtain an atx pc power supply to power them instead.

Thanks once again.

Out of interest what is a "rectified AC" and how is it different to DC?

chriselias272 said:

Out of interest what is a "rectified AC" and how is it different to DC?

Click to expand...

It's simply a series of half-sine pulses, DC is a smooth voltage.

To be honest, if your knowledge is zero, you shouldn't be messing about with this!.

As it's for the lighting installation in a kitchen you should use the proper power supply for the job - you still appear to have no idea of even what the power requirements are?.

I would suggest you get a beefy regulated 12V power supply - either a wall wart or a closed frame unit. make sure it is regulated. most wall warts aren't. Also, get one stamped UL on it if you are in North America (dunno, EU stardards). This will be a real benefit if you burn down your house as insurance won't pay otherwise.

and you should definitely listen to Nigel - if you don't know what you are doing, stop now.