Ramsey Electronics CW-700, Manual

Page: 6 / 27

CW700
•
6
CIRCUIT DESCRIPTION
Looking at your circuit, you will see that the circuit can be broken down into
four basic parts.
The first part is the power supply. The power supply circuit converts the nine
volts DC power coming into your circuit into the clean five volts needed to
power the computer circuitry properly. With such a power supply, the
CW700 can take a large range of input voltages and still function perfectly.
Another part of the circuit is the touch sensitive paddles. When you touch
them, the pad senses your finger. The 74HC04 inverter simply sends out a
signal to the microcontroller telling it whether or not the paddles are being
touched. This circuit is what provides the “magic” in the touch paddles. We
would like you to know that throughout this whole process, there is no
danger from any high voltage going through your finger.
The third part is the 68HC705K1 microcontroller chip, the X2402 memory
chip and the surrounding logic. This is the “nerve center” of the circuit. The
microcontroller monitors the switches and paddles and has a program that
interprets your commands. When it determines that a switch was pushed or
that a paddle was touched, it consults it’s program with what to do. In order
to insure that your microcontroller is functioning properly, we test and
program each and every one right here at the factory. This ensures the most
reliable product. Our optional memory kit, the CW700MX replaces the single
memory chip with many, offering you space to save up to thirty-two
messages.
The input/output circuits are the fourth part of the circuit. These circuits are
what interface the microcontroller to the outside world. They include the
buttons, LED, speaker and all of the jacks. These are some of the reasons
why your key is so versatile. In fact, we have even included a jack that sends
out computer pulses. With so many interfaces, you can use the CW700 for
what you want. Many keyers on the market limit you to hooking up to a
specific radio input or using the internal speaker. Your Ramsey keyer can go
as far as your imagination and skill takes you.