Direct PC access through the mounts DB9 connector

This page presents an alternate option to directly control your mount`s stepper motor board. There is not much difference in terms of stepper control functionality from the original modification as they both allow commands to be sent from the PC directly to the stepper controller board. The difference between the two basically is the number of ele
 Direct PC access through the mounts DB9 connector - schematic

ctronic components required for the mod. The original one requires only three components;the 74HC157 mux chip, a 10k ohm resistor, and a toggle switch which are all soldered on the handcontroller circuit board. The option below does not require you to connect the handcontroller but would require you at least 10 electronic components not including the PCB, serial cables, casing, etc. The reason why the original mod has lesser components is that it utilizes the rs232-TTL conversion circuitry of the handcontroller while the diagram below would require you to produce the same rs232-ttl conversion on a separate circuit board. In any case these two options are identical in terms of functionality and are presented providing the user two possibilities to control the stepper motors of the mount. Figure 1 shows a diagram that will allow you to directly connect your PC to the Mount`s DB9 Handcontroller Port. The port contains both the 12V power lines and the two TTL level serial data lines. It allows the user to send the commands from the PC`s serial port to the mount`s handpaddle DB9 port. The circuit utilizes two major components; a RS232C-TTL converter (MAX232) chip and a 5 Volt voltage regulator (7805) that supplies power to the max232 chip. The 7805 source of power comes from pins 1 and 8 of the mount`s DB9 connector. Extra care should be provided in avoiding these lines to be inerchanged/shorted to the TTL level lines (pins9 and...

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