Celestron Compustar Manual de instrucciones descargar pdf (Pagina 26)

unless they are autoguiding directly from one of those devices instead of using an RJ-11 cable

from an autoguiding computer. If the reader will be using one of those devices, then they may

simply follow the indicated pin out for the wiring of the relay box. However, not having any

experience with such cameras, the author advises readers attempting to autoguide with them to

consult a competent electrical engineer before proceeding.) The RJ-11 cable will enter the

plastic box, but once inside it will be cut and the 6 color-coded wires splayed out to permit the

wires to make connections within the box. Thus, as implied earlier, the modular jack plug on

the opposite end of the RJ-11 cable will not be used.

Next the wiring diagram shows the RJ-11 wires leading into 4 push buttons on their way to the

relays. However, these buttons are not necessary (see Enabling the Autoguider below) and

may be safely omitted. Rather, the color-coded RJ-11wires can be connected directly to the

components of the relay box as shown in the wiring diagram above. Thus, the guiding

computer outputs that are conducted along their corresponding RJ-11 wires will open and

close the proper relay switches inside the box to effect changes in the drives for the X and Y

axes. The DB-9 cable, also cut with its wires splayed out inside the box, will exit the other end

of the box, terminating in the male DB-9 connector pins that will be plugged into the female

guide port on the Compustar computer module. The wires will lead to various pins of the DB-

9 connector as indicated on the left side of the wiring diagram. Pin 1 of the female DB-9

connector on the Compustar computer module controls the +X and –X movements and pin 3

controls the +Y and –Y movements. Whether the motions in the respective axes are in the +

are – direction depends upon whether the corresponding relay switches are opened or closed.

The relay box will derive power to operate the relay switches by drawing +5V DC from the

Compustar computer module off pin 8 of the DB-9 connector. DB-9 pins 6 and 7 provide

ground for the relays.

Lastly, there will be 2 potentiometers wired into the system on the circuit board within the

relay box and connected to pins 1 and 3 of the male DB-connector. These are provided to

balance the inputs to the X and Y axes so that there is no movement of these axes when no

corrective input is commanded by the autoguiding computer. In other words, if the inputs are

not balanced, simply connecting the autoguider relay box and activating it can start movement

of the mount in one direction or the other in one or both axes. Adjusting the potentiometers

can balance the inputs and null out the motion. Thus, access to the potentiometers from outside

the box must be provided so they can be adjusted, if necessary. They are usually adjusted by

turning screw heads with a small screwdriver. Access can be as simple as small holes drilled in

the side of the box to allow passage of a small screwdriver.

It is also important to note that pin 9 on the DB-9 male connector must be grounded. On the

left side of pin 9, the wiring diagram indicates that it is connected to pin 3 of the ADC809 chip

(analog to digital converter chip) inside the Compustar computer module with 1.8k ohm pull

up. The original Borgman diagram also indicated “no connection” on the right side of pin 9

(this has been deleted on the modified diagram). The experience of the author was that the

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Celestron Compustar Manual de instrucciones Pagina 26