+/- 12 volt dc from geo

[bent]

hello,

i'm building the sub-commander, and it's need +12vdc, -12vdc and a ground,

i'm planning to use the dual supply regulated from geo, and use 7812/7912....

does anyone know the value of the 2 cap that goes in the in , and do i keep the value of 2 X 10uf on the out ?

thank you...
i allready check with this link http://www.diystompboxes.com/smfforum/index.php?topic=62799.0 but he want's to use 9 volt to get is +/- 12vdc, me i'm going to use a wall or desktop transformer with 18vdc or 24vdc...

thank'S

bent

[R.G.]

i'm planning to use the dual supply regulated from geo, and use 7812/7912....
does anyone know the value of the 2 cap that goes in the in , and do i keep the value of 2 X 10uf on the out ?

The rest of that Power Supplies Basics article tells how to calculate the input capacitors. Their value depends on how much current goes out, how much peak voltage is coming in from the transformer, and whether you're using full wave rectification with a center tapped transformer or half wave rectification with a non-centertapped transformer.

It all depends. But 1000uF should work in most cases, just as a starting point. Do the math.

i allready check with this link http://www.diystompboxes.com/smfforum/index.php?topic=62799.0 but he want's to use 9 volt to get is +/- 12vdc, me i'm going to use a wall or desktop transformer with 18vdc or 24vdc...

If you're using a *DC output* transformer, then you'll need the same sized caps as above. Your transformer output must then be at least 28Vdc to provide enough headroom for the regulators. If you use an *AC output* transformer, then you must use a transformer of at least 11-12Vac output under full load if you do the half-wave rectification, and 22-24Vac center tapped if you do the full wave rectification version.

If you're planning to simply put 28V*dc* across two regulators, also place a 1K resistor from the output of each regulator to circuit ground to keep the ground balanced. The regulators will be happier. They can only supply current one way (through the output) and cannot eat any significant current coming in through their ground terminals.

[bent]

yeah !!!!!

thank's RG... always there when we need you....

bent