the short circuit into P8 position. In this case we do not turn the antenna. The value on the display is that volt-
age which is calculated by the computer. The processor needs this value from the antenna-rotator. For full scale
deflection 3.6 Volts are necessary on both inputs. Use the CX6DD.COM (GS232) driver for communication.
The necessary parameters are 9600 Bd, 8N1.
Construction
The PCB is similar to the previous one. It’s not too complicated to produce. For providing the necessary supply
and reference voltages, we use two voltage regulators but for the sake of simplicity, the reference voltage regu-
lator can be omitted and the voltage source of the main regulator can be used for this purpose. Depending on
the factory of MAX232 it can happen that the inverter inside of the circuit does not work properly. In this case
we have to use tantalum capacitors – or depending on the production technology smaller capacitor values can
be chosen which may be as low as 100 nF for a CMOS product. In case of appropriate operation on pin 2 of
9.4 V, while on pin 6 -9.4 V must be measured. If the voltages are equal to these values adjust the
variable resistors into middle position.
Display
Operation
It is connected to the processor by three data lines using serial data transfer. The circuit contains six shift regis-
ters which convert serial data coming from the processor to parallel data for the LED displays. Operation is as
follows: Data arriving to the input is shifted by the clock signal continuously one place forward in the register.
When all the 48 bits are on the right place the strobe signal copies data to the output of the register. The advan-
tage of this method to the widely used multiplex method is that the light intensity of the displays is higher and
they do not vibrate.
