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SPC900 LXmod yesyes style ;-)

yesyes

By yesyes
in DIY Astronomer

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yesyes

yesyes

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Inspired by this thread I have finally also done the LX and amp off mod on one of my SPC900 webcams.

I want as few cables as possible, so I made a version that really only needs one USB cable to the modded cam.

Ingredients:

1 SPC900

IMG_4523.JPG

One LX and amp off mod circuit

IMG_4538.JPG

One 4 port USB hub circuit board (I chose this particular hub because the circuit board would be rather small not having to accommodate the USB sockets)

IMG_4554.JPG

One Prolific PL-2303 based USB to serial converter

IMG_4559.JPG

And one ABS project box of just the right size

IMG_4576.JPG

Result: One LX and amp off modded SPC900 that only requires a single USB cable and is not that much bigger than the original webcam.

IMG_4585.JPG

IMG_4580_labelled.jpg

More pictures here:

https://picasaweb.google.com/chris.yesyes/201107SPC900LXAndAmpOffMods#

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OK, I've made some schematics of the whole thing (I hope malc-c doesn't mind that I have re-used parts of his diagram).

This shows how everything connects together. I hope that explains it a bit better. Any questions, just ask...

SPC900-LX-diagram.jpg

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Gina

Gina

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OK - ordered that (great price and free shipping) :D Now, what about the USB to serial adapter? Can you recommend a source for that, please? :p If I get what you used I know it will work :)

Incidentally, I've just ordered another webcam from Morgan to use for a wide angle (almost whole sky) camera to go with my weather station. I want long exposures for that too.

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Gina

Gina

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The nights are getting longer and it won't be long before I have a usable pier with mount so I may well soon be ready again for doing some imaging. And having this webcam, thinking about the mod for long exposures. So I'm getting things ready.

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OK - ordered that (great price and free shipping) :D Now, what about the USB to serial adapter? Can you recommend a source for that, please? :p If I get what you used I know it will work :)

Choosing a USB to serial adapter can be a bit tricky. For these mods you need one that supports the handshake lines RTS and DTR, not only the serial data lines (we don't even want to send any data). I also wanted one where Win 7 64bit drivers were available.

I found out that the Prolific PL-2303 chip fits the bill. So any adapter with that chip will work fine. You would have to check if it has Linux support if you're planning to use your Linux machine for astro.

So I bought some of these:

USB to RS232 Cable Adaptor with PL2303+PL211 Chipset on eBay (end time 17-Jul-11 18:07:45 BST)

The circuit board is in the serial plug. So I carefully cut it open and unsoldered the USB cable (make a note of which wire goes where). The most difficult part of that is to get rid of the DB9 plug without damaging the solder pads on the PCB.

Once you got it off you got a nice small USB to serial PCB. The USB side of it will then be soldered to one USB out port on the USB hub. 3 wires go from the serial side to the LX and AmpOff circuit. I used the wires from inside the remaining USB cable. They are small and flexible. Too stiff wires can take off the tiny solder pads.

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yesyes

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Also did you glue the nose adapter to the piece of plastic ?cheers dazz

No. The only thing that is glued is the 2 green pieces of acrylic. The acrylic is held down by the 2 screws you can see at the front. And it holds the nose piece down. There is a bit of play but the outer box is so small that the webcam board can't move much so the nose piece won't move much either.

I thought long about how to hold the nose piece in the box. I couldn't glue it in because then I couldn't have unscrewed the webcam anymore (not enough room to turn the board).

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Gina

Gina

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Choosing a USB to serial adapter can be a bit tricky. For these mods you need one that supports the handshake lines RTS and DTR, not only the serial data lines (we don't even want to send any data). I also wanted one where Win 7 64bit drivers were available.

I found out that the Prolific PL-2303 chip fits the bill. So any adapter with that chip will work fine. You would have to check if it has Linux support if you're planning to use your Linux machine for astro.

So I bought some of these:

USB to RS232 Cable Adaptor with PL2303+PL211 Chipset on eBay (end time 17-Jul-11 18:07:45 BST)

The circuit board is in the serial plug. So I carefully cut it open and unsoldered the USB cable (make a note of which wire goes where). The most difficult part of that is to get rid of the DB9 plug without damaging the solder pads on the PCB.

Once you got it off you got a nice small USB to serial PCB. The USB side of it will then be soldered to one USB out port on the USB hub. 3 wires go from the serial side to the LX and AmpOff circuit. I used the wires from inside the remaining USB cable. They are small and flexible. Too stiff wires can take off the tiny solder pads.

Looks just the job, thank you :D I'll order a couple of those.

EDIT... OK done that :p Ordered.

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Gina

Gina

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Now have webcam, 4 way USB and USB to RS232. Now need to check what components I have

for the home made bit (transistors etc.) and get a box. The USB hub and RS232 boards are even

smaller than yours yesyes. I'll take a photo or two. Everything came apart without any problem.

Biggest difficulty is finding a box small enough, though a couple of the Maplin ones aren't all that big.

It's just that it would be nice to make it as small as possible. I don't think all the bits will quite fit

into the original case :)

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Gina

Gina

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One thing puzzles me... What is that green piece of plastic in the bottom of the box and why is it there?

I have most of the components - BC546 transistors, 1N4148 diodes, resistors, switch, strip board and I've found a box that seems OK.

What I can't seem to find is an 11v zener diode - I did have some but must have used them. I've got two 5.6v which will give 11.2v

but with a higher resistance than one 11v zener.

post-25795-133877635171_thumb.jpg

post-25795-133877635179_thumb.jpg

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yesyes

yesyes

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One thing puzzles me... What is that green piece of plastic in the bottom of the box and why is it there?

I have most of the components - BC546 transistors, 1N4148 diodes, resistors, switch, strip board and I've found a box that seems OK.

What I can't seem to find is an 11v zener diode - I did have some but must have used them. I've got two 5.6v which will give 11.2v

but with a higher resistance than one 11v zener.

Looking good so far Gina. ;-)

The green piece of acrylic is holding the nose piece of the webcam in place. There is a link to more pictures at the bottom of the first post. These might make it more obvious what it is for. ;-)

To be honest I'm not quite sure what that zener diode is for. So can't suggest an alternative. Haven't really tried understanding the circuit (this time), just copied it... ;-)

I did wonder what a 11V zener is doing in a 5V circuit...

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