12v power supply question

[doug deeper]

ive never built a power supply before so i just want to double check.
i need a 12v supply and the smallbear flatpack looks perfect!
i looked over the project at ggg (http://www.generalguitargadgets.com/pdf/ggg_reg_power_supply.pdf)
that uses this for a 9v supply. if i want to use it for 12v do i just omit the
regulator and the following cap? or should there be other changes made?
thanks in advance!

[bancika]

no, just use 12V regulator instead, it's called 7812. you will also need few more volts at transformer to start with, 12V would be enough, although it should work with 12V transformer. When rectified you'll get about 16V but diodes will eat some voltage as well as regulator.

[doug deeper]

hmmmm, well the extra voltage wouldnt be a problem.
i didnt want to use a 12v regulator because it knocks the supply down from 200ma to 100ma.
would it work "my way" or am i asking for trouble?

[doug deeper]

oh yeah, im planing on using this to power a 12al8 12v tube.
so 100ma might not cut it.

[bancika]

if you want to get rid of regulator you can replace it with a resistor.Try wihout resistor first and if you get more volts that needed just calculate value according to ohm's law with given voltage difference and load you have. Heater load is 550mA for that tube...

[doug deeper]

ahh so that wont do at all!
thanks for the help though!
where did you find the current draw info on the tube??
i havent been able to track it down.

[bancika]

google 

[doug deeper]

never heard of it!     

[brad]

You need the 1Amp version of the 7812.  It's bigger and generally needs a bit of heatsinkage too.

[bancika]

7812 is 1A version, 78L12 is smaller, transistor like regulator rated at 0.1A
yeah, heat sink is recommended, I use large one 6V regulator for my tube preamp which draws 0.6A and it gets very hot

[doug deeper]

does anyone know of a 12v 1a transformer in a similar package? (with a similar price! )

[bancika]

12V transformer is pretty much standard, so you'll find it anywhere. Every electronic suply store carries them