Construction Notes for the rev C12 FM Stereo Generator	GFC 4-11-2000

Important: the LM833 op-amps love to oscillate, in this circuit most of them
have 10pf bypass caps to prevent this, U10A doesn't have the cap and will
oscillate, add a 10pf capacitor across the 10K resistor, R70, that will fix
the problem.

The 38Khz mux level doesn't go down to zero, I changed the feedback loop
on op-amp U12A, remove the 10K trimmer R68 and the 4K99 resistor, R107
then add a 47K fixed resistor from U12A pin 1 to 2.  Cut the line between
TP7 and R73, connect a 1K trimmer as follows:

CCW terminal: Ground
CW terminal: to U12A pin 1
Wiper terminal: to R73 on the cut side.


It is possible to build the circuit board using a single sided board
made with press-n-peel blue laser printer transfer film.  I highly
recommend printing the component side silkscreen on the top of the
board, do this after etching and drilling.  It is necessary to mirror
image the silk screen file before printing it on the press-n-peel,
do that as follows: (thanks to RCD)

Go to line 462 of file Top_silk_screen.ps and change this:
--------
%%Page: 1 1
%%BeginPageSetup
--------
to this:
--------
%%Page: 1 1
8.5 72 mul 0 translate -1 1 scale
%%BeginPageSetup
--------
Just iron on the press-n-peel silkscreen, clean with tape, and leave it.
Now you can easily stuff the numerous parts.

The + and - power supply inputs need a number of jumpers on the bottom of the
board and all of the - supply lines need to be hand wired.  Also, there are a
number of wide copper areas that need to be grounded via jumpers, notably
the ground side of C21.  Check continuity between the power supply ground pin
and the various wide copper ground areas on the board.  Using insulated
jumpers, connect the grounds that are open.