"Father Haskell"
"Phil Allison"
"Father Haskell"

Homemade, powered by small 13 vct transformer from an old
boom box and LM317T regulator (ps seems capable of 14v clean
power, easily). Sounds like it's picking up the nearest AM station,
especially loud and clear when I touch the volume and gain control
shafts. Touching the heat sink behind the 317 with a fingertip
_quiets_ the interference, though.

** Lemme guess - you have the IC in a plastic box with no shielding of
any
kind ?

Wooden box, open, power supply board and transformer laid
on workbench and connected with jumpers.

** RFI heaven.

Pun intended......

Ideally, there needs to be a metal box that is connected to the negative
supply, pin 4 of the IC plus the metal parts of any pots. Alternatively,
connect the metal fames of each pot to the negative rail ( pin 4) and
add
a
cap of about 2200pF across pins 2 and 4 to bypass radio frequency
energy.

Easily fixed by covering the inside of the box with foil duct tape.

** Maybe so, but making reliable electrical connection to such foil is not
so easy.

Nuts, bolts and solder lugs are essential.

8 x 1 sheet metal screw with wire end bent 180 and clamped
between two washers.


The volume pot wiper needs to be de-coupled from pin 2 by a series
combination of a 4.7 kohm resistor and a cap of about 0.1 uF. This stops
DC
voltage from pin 2 appearing on the pot and helps with RF suppression.

http://www.national.com/ds/LM/LM386.pdf

http://fluxmonkey.com/electronoize/386amplifier.htm
modified by adding 25 ohm volume pot to the output end,
with the wiper connected to the speakers ( 2 x 3.3 ohm, series).

** I'd call that an output attenuator - not a " volume pot ".



So you control volume by controlling input?


** You after help is just like picking fights ?

Cos you are being damn rude.


..... Phil