Thursday, January 03, 2008

Motorized RA and DEC hack for TG-SP II

I bought four SPDT switches from Apliu Street and they're $8.5 HKD each, some are as expensive as $20 HKD each... those metalic models are selling at $80 HKD if I remember correctly, hey, they're just switch!!! The model I bought are pretty big.

Anyway, I also bought four smaller SPST switch, they will be used to mimic ST-4 autoguiding signal with a pull up resistor arrangement. This will be the next step with the L298 based kit set comes, which I expect would be like one or two weeks later. I didn't buy any resistors and I will be using some old ones removed from my now replaced indoor wireless phone, and since they're old ones, I didn't buy any circuit board, too.

I quickily connected the SPDT switches with one of the motors, and I successfully got a prototype which can control the motor to go CW or CCW. Adding a small resistor plus a small variable resistor, I can even control the speed of rotation, not bad, right?

Right now the problem is that, I failed to locate any suitable shaft coupler to connect the motor to the slow motion control shaft. I shouldn't mention the word suitable, I actually find no shaft coupler from Apliu Street. Maybe I will need to shop around online. I also couldn't find any M1.5 screws for mounting the motors on a board.

To connect the motors to the hand paddle, I will be using the socket pair, plus the cable from the old wireless indoor phone, it consists of four wires and that's just enough, it's going to be quite elegant, too.

So, to finish the first phrase of the project, i.e. to motorize the RA and DEC slow motion control of the TG-SP II, I need to find the followings:-

1. shaft coupler to connect 3mm shaft to 6mm shaft, I need two of them

2. a suitable sized plastic board, to mount the motors there, and to install a 4-pin socket there to connect to the hand paddle

3. to find a small plastic board, to host that four SPDT switches, the batteries pack (AA * 2?), and another 4-pin socket.


BTW, I found those 5V relays from Apliu street, and they can be found in many shops, cheaper than from ebay.

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