1. You can only print this schematic on an EPSON-compatible
2. I used batteries to power this circuit. It requires 12V,
which means 8 AA batteries. You could also use a 12V power
supply, but it has to be **QUIET**. I think the batteries
are easier. Since the circuit will only be on for a short
time, they should last just about forever.
3. Wire this circuit carefully and don't screw up any of
the connections. Take your time.
4. Wiring layout isn't critical. You should see my sloppy
5. All parts are available at MidState Electronics on
Monterey St. You can save a little by buying the Mic at
Radio Shack, though.
6. Cost for the electronic components should run about $15,
but the cabinet and other hardware bring the price up. For
resistors and capacitors, go to the counter and just buy
what you need. Avoid the packaged goods.
7. USE SOCKETS FOR THE ICs!
8. Observe polarities on the electrolytic capacitors.
Serial Port Notes:
If you have a DB-25 connector on your serial port, the pins
for this circuit are:
CTS ---------- Pin 5
Signal Ground -- Pin 7
If your serial port has a DB-9 connector, pins are:
CTS --------- Pin 8
Signal Ground -- Pin 5
When you first try this circuit, don't be surprised if it doesn't work.
The adjustment of the 50K pot is critical. For me, it worked almost
exactly in the center of the pot's travel. Experiment!