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SPC900 LXmod yesyes style ;-)

yesyes

By yesyes
in DIY Astronomer

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yesyes

yesyes

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What sort of a cable do I need to use the SPC as a guidecam? I'm uncertain about how the setup looks like.

The USB cable from the camera to the PC, if you use the USB-only mod. For standard mod it will be USB cable and serial/parallel port cable.

This feeds the video into your guiding software.

The guiding software then needs to be able to control your mount, usually via ASCOM. So you would need an ASCOM driver for your mount and the appropriate cable to connect your mount to a PC.

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yesyes

yesyes

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Of course I'm still reading my own thread.. ;-))

I'm not aware of a guide but I'm sure I'd be able to help.

I assume you already have a modded cam that has the parallel port variety of the mod? Do you happen to have the circuit diagram of the mod you used?

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Russe

Russe

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Thanks!

Say, what sort of a USB splitter are you using on your comp? I have only 3 ports and ever since I spent too little money on a rs232 to USB port which didn't work half as well as it needed to, I'm a little wary of what to get...

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yesyes

yesyes

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Sorry for the delay, I'm rather busy recently. ;-)

This can be done and you have 2 options as far as I can see.

If you have/get an USB-to-serial adapter with RS232 voltage levels (+-15Volt), then you can use the circuit in the first image. The left side connects to your existing mod (GND and "LX Signal"). The 5Volt supply on the right can also come from the 5V on your existing mod. The right side would connect to the serial port on the adapter. Since you get +-15V on these you need the diode (to block the negative voltage). The transistor makes sure you only get 5V levels on your "dead bug" IC. The transistor does invert the signal, but most capture software have a setting to invert the signal, for example SharpCap.

The part of the circuit below the GND line is optional. This part is the amp-off mod. If you don't want that, just ignore everything below GND.

If you get an USB-to-serial adapter with TTL levels (5Volt), then this will be a lot easier. You already get the 5V levels that your dead bug needs, so all you need is a current limiting resistor between RTS on the serial port and LX-Signal on your existing mod. See 2nd image. Again, ignore everything below GND if you don't want to do the amp-off mod.

post-2143-0-93857800-1347472475_thumb.pn

post-2143-0-03108700-1347472487_thumb.pn

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themos

themos

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The original Parallel port design was going to put +12V on the LX signal line (with a 220R in line), no? I can't quite see how putting 5V on it (with 10K in line) is going to work but I'll take your word for it! I am guessing the 3V3 is not going to cut it.

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yesyes

yesyes

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Ah, I see. I somehow assumed that this HEF4066 was a TTL level chip. Having just read the datasheet, it seems to be OK with levels up to 15V. So there's no need for that transistor in the first image even with an RS232 levels serial adapter.

Also, there would be no need for that 10k pull-up on the first image as that is already present in your existing mod. Come to think of it, that in-line 10k resistor is a bit too high. It has to be significantly lower than the 10k pull-up to 5V. Not sure where my mind was last night.. ;-)

So this is in fact a lot easier, even with an RS232 levels adapter. Just use the same circuit as with a parallel port but connect the LX Signal line to RTS on the serial port.

The 3.3V adapter may or may not work. I didn't find a minimum voltage in the datasheet. It's worth a try if you already have that adapter.

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themos

themos

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Just use the same circuit as with a parallel port but connect the LX Signal line to RTS on the serial port.

That sounds nice and simple! I will try the 3V3 adapter , I don't think I can fry anything. Worst that can happen is it's not going to work.

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pwalsh61

pwalsh61

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I have an old Toshiba laptop with parallel port, 2 x USB but no serial, and a Dell Latitude D630 with serial port, 4 x USB but no parallel. I've just completed the "dead bug" LX mod (parallel port version) and was interested to see the circuits shown last week as I've been looking for a way to connect the modded cam to either laptop. I have a Belkin USB to serial converter which I believe has the Prolific chipset. What I don't know is the voltage levels would they be +/-12v or +/-5v? I have it in mind to alter my mod so that instead of the parallel cable I'd have a DB9 connector on the project box and then have a choice of DB9 to DB25 to connect to the parallel port of the Tosh, or DB9 to DB9 (with the "BC547" circuit) to connect to the USB/serial (which I could use with either laptop). I wouldn't be connecting to the DB9 serial of the Dell as that would be used for connection to the mount for EQASCOM

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  • 1 month later...
harshal

harshal

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Hello All

Popping up after a very loong time with a very silly sounding question:

I am trying my Win 7 Home Basic to recognize the prolific usb2.0-serial cable but no success. Any pointer to a post / forum?

I am sorry to put this question here and distract you all.

Thanks in Advance

Harshal

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  • 3 weeks later...
themos

themos

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Hello again! I can report that I just tried out the 3.3V adapter cable (FTDI TTL-232R-3V3) and it works! I bypassed the 220R on the parallel port circuit and connected the RTS line (green cable) of the 3.3V cable directly to the "LX signal" of the circuit

http://www.ftdichip.com/Support/Documents/DataSheets/Cables/DS_TTL-232R_CABLES.pdf

Now, I just need to remove the old parallel cable and solder in the new 3.3V FTDI cable.

Ah, I see. I somehow assumed that this HEF4066 was a TTL level chip. Having just read the datasheet, it seems to be OK with levels up to 15V. So there's no need for that transistor in the first image even with an RS232 levels serial adapter.

Also, there would be no need for that 10k pull-up on the first image as that is already present in your existing mod. Come to think of it, that in-line 10k resistor is a bit too high. It has to be significantly lower than the 10k pull-up to 5V. Not sure where my mind was last night.. ;-)

So this is in fact a lot easier, even with an RS232 levels adapter. Just use the same circuit as with a parallel port but connect the LX Signal line to RTS on the serial port.

The 3.3V adapter may or may not work. I didn't find a minimum voltage in the datasheet. It's worth a try if you already have that adapter.

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themos

themos

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Ah, problem is, it works with SharpCap but PHD Guiding is not playing along with Serial port control. I switch the brain setting to LE Port COM8, but it switches back to Port 378. Also, I don't have the option of telling PHD Guiding that I have connected the RTS line to the LX control. Anyone know the resolution to these?

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Gina

Gina

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I'm pretty sure I had it working with PHD but can't be completely sure as I upgraded to a QHY5 some time ago and my memory is virtually non-existent! There's probably a post about it somewhere in these forums but please don't ask me to look for it :D

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themos

themos

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Resolved the PHD problem. The COM port number that the USB-serial adaptor had been given was COM8. PHD does not like anything above 4, I think. The solution was to plug in all my FTDI cables and note the assigned numbers. It turns out I have 5 of those ( and probably more because I saw numbers 3,4,5,6,8): One for the EQ6, one for the EQ1 autoguider, one for the ASCOM focuser, one inside the original Arduino and one for the LX webcam. In Device Manager, with all devices connected, I right clicked on each USB Serial Port (COMn) and selected Uninstall. Once they were all gone, I unplugged them and then plugged in the LX webcam one. It got assigned COM3 so now PHD will use it happily.

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