wrote in message
...
I'm reading this thread with some interest, but I'm more
puzzled as it
goes on, there should be something we are (and the OP is)
missing.

On 16 Nov, 19:11, "robb" wrote:
"clifto" wrote in message

and although the numbers may seem incorrect from a
electronic
formulaic analysis i can only report what i see on the
equipment
i use and with the setup i use.

The DMM amp reading numbers were fluctuating wildly on my
last
test and 1.57 ???was something i thought flashed by as
highest #
maybe it was .57 but i do know that whatever the number the
100
ohm resistor had a stream of smoke going up and the 7805
appeared
to have a puff of smoke released before i could dis-connect
now
i am hopping somebody can help me decipher what went wrong
with
my testing


hmm 78xx don't smoke easily, maybe if you apply a too high
input
voltage ( 30V I believe) or if it goes into self-oscillation
if an
output capacitor is omitted. A 100 ohm resistor, assuming we
are
talking about a 1/4 W one or bigger, shouldn't smoke easily
with only
5V even on a short to ground, it should become quite hot but
not smoke
instantly, if it smoked I believe the input voltage was higher.

thanks for help Francesco,

i do not under-estimate my ability to mis-understand.
so i consider myself missing something as distinct possibility.

but what ?

source is a 18-24v ac 1000mA wall wart that feeds the bridge and
then 7805.


Power supply problems shouldn't be that difficult to
troubleshoot,
even if once I had almost the same problem with a simple three
tubes
amplifier, but that was another story :-)

someoner suggested that i add caps to prevent oscillation i will
try and i hope to give more accurate report and numbers after i
make the change.

thanks for help francesco and any other ideas you may have,
robb