[Boatanchors] OT audio amplifier

[Dick KF4NS]

Many replies so will not include all of them. To the question 
regarding schematic marking, yes with a but. The copy I have is a 
Xerox copy and it appears that the plus was hand-written on it before 
it was copied. The plus is toward the input resistor Ri and the 
negative input pin 4 inverting terminal of the chip input transistor.

Two of you gentlemen have opposing views of the concern for polarity. 
I think I will build it on breadboard and flip it both ways for a 
test.

Thanks very much for all the input.
73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!

----- Original Message ----- 
From: "Jim Wilhite" <w5jo at brightok.net>
To: "Dick KF4NS" <kf4nsradio at verizon.net>
Sent: Wednesday, July 13, 2011 4:51 PM
Subject: Re: [Boatanchors] OT audio amplifier


: Is it marked with a +/- or is it a bipolar?
:
: Jim/W5JO

----- Original Message ----- 
From: "Heinz Breuer" <hbreuer at debitel.net>
To: "Dick KF4NS" <kf4nsradio at verizon.net>
Sent: Wednesday, July 13, 2011 4:31 PM
Subject: Re: [Boatanchors] OT audio amplifier


: Hello Dick,
:
: you can certainly use a 2.2ufd foil capacitor but it is much larger 
in
: size and much more expansive. The input resistence of the integrated
: circuit is pretty low. The coupling capacitor forms a highpass with 
the
: input resistence. You need a large coupling capacitor or you would 
cut
: off too many lows. We are talking about millivolt levels here. 
Polarity
: does not really matter.
:
: vy 73 Heinz DH2FA, KM5VT
:
: Am 13.07.2011 22:09, schrieb Dick KF4NS:
: > I wish to pick your brains. Does anyone remember or have you built 
an
: > audio amp replacement for the LM386 using the SSM2211 as was in CQ
: > under the column Math Notes?
: >
: > The copy of the article I have shows a 2.2ufd electrolytic as the
: > input coupling capacitor. Being a hollow state born and bred guy, 
this
: > puzzles me. Why an electrolytic?
: >
: > I am sorry but I cannot find what issue that article was from but 
the
: > amp circuit is pretty darn close to the spec sheet from Analog 
Devices
: > which shows their "typical application."
: >
: > 73, Dick KF4NS
: > St Petersburg, FL 33714 USA
: > Keep The Glow!
<<SNIP>>

----- Original Message ----- 
From: Brian Harris
To: Dick KF4NS
Sent: Wednesday, July 13, 2011 5:10 PM
Subject: Re: [Boatanchors] OT audio amplifier


Electrolytics are smaller for the same capacitance compared to 
non-polarized capacitors.  In this application there is always a small 
DC bias on the electrolytic so you must pay attention to the polarity.


Brian Harris, Field Application Engineer
cell 214-763-5977 (preferred)
office 214-553-4330
email cosmophone at yahoo.com