power supply cont..

[sigma]

hi again
here's what i came up with
it's some sort of i'mprovement over
my first ckt.
it's working and all but
the voltages are sligthly off
around .5-.7v
:?
any ideas what i could do to
fix this tnx

 

[kinjalgp]

Whay have you used those 2W resistors? I don't think there is any use of them in the circuit except you wish to limit some curent. But these ICs already have a thermal shut-down which will switch-off the output current flow as soon as its temperature goes beyond a preset value.

 

[bogdanfirst]

it seems that you have a pin from the second rectifier unconnected. is it just a graphic error?
and, yes, you dont need the 2W resistors, and if you stil use them you will have more power disipated at the maximum current drawn from the suply.

 

[bogdanfirst]

here are basicly 2 ways that i would make it.

 

[sigma]

both ideas are good and i will look into improvements but could someone
tell me how to stabilize the voltage.

 

[Sebi]

And this is better, because the dissipation is lower on 7805. When You need for 12V only 100...200 mA, connec it to lower input voltage.
7805, 7812, and LM317 outputs voltage stabilised.

 

[bogdanfirst]

yes, an even more improoved idea.

 

[sigma]

tnx for the ckt. sebi
will make the modifications to my ckt.
Oh and to answer your question bogdadnfirst
that unconnected pin is not a typo it's just unneccesary.
tnx again guys.