SPC900 LXmod yesyes style ;-)

[Russe]

By the by, which capture software do you guys use with the LX modded SPC900?

[yesyes]

SharpCap works very well

[Russe]

Yep, that's the one I'm using...

[Stevie P]

Hi Yes Yes

I wonder if you could clear something up for me..

I carried out this mod via your instructions and have had some remarkable results.

I am a little confused on how the "amp off" side of the circuit works, is it dependent on settings in capture software or does it kick in when LX mode is switched on?

Thanks in advance

Steve

[yesyes]

The capture software has to activate amp-off. It is active when the DTR line on the serial port is high. It is independent of that LX switch that is part of the mod.

[Stevie P]

The capture software has to activate amp-off. It is active when the DTR line on the serial port is high. It is independent of that LX switch that is part of the mod.

Thanks for that, I use Sharpcap and have set "amp off control Line" to DTR in LX control settings, I assumed this was how it was done but was just looking for confirmation, so Thanks again

Steve

[Russe]

I never figured out what DTR line means. Neither the other one you can chose from in Sharpcap.

[yesyes]

DTR and RTS are signal lines on a serial port

http://en.wikipedia.org/wiki/Data_Terminal_Ready

http://en.wikipedia.org/wiki/RS-232_RTS/CTS#RTS.2FCTS_handshaking

[Russe]

How would I know which one to use?

[yesyes]

hmm, the circuit determines that. In this case DTR controls ampOff and RTS controls long exposure.

We're not actually using the serial port for data transmission here. We only use the 2 lines DTR and RTS like digital outputs that can be switched on or off from software.

[harshal]

Hello Everyone

The SPC900 webcam has almost vanished from the market and I was wondering if any one of you have found / tested a replacement that works similar, if not equally well, to that of SPC900.

Thanks

[CedricTheBrave]

Hi, I purchased a USB to serial converter and the pins are named 3v3' vcc, txd, rxd and gnd

Can I use these or do I need to choose another board with dtr and rts?

I think it's a ttl uart

Many thanks

[yesyes]

Do you have a link to the adapter and/or a datasheet?

[CedricTheBrave]

yes its this one from Amazon http://www.amazon.co.uk/PL-2303HX-PL-2303-Drivers-available-Windows/dp/B00AVRIDB0

[yesyes]

Yes, that should work. It's TTL

Come to think of it, both TTL and RS232 levels should work. The diodes protect from the negative voltage on RS232. With a TTL level adapter you don't need the 2 diodes (connected to the RTS and DTR lines) but they do no harm either.

[CedricTheBrave]

So do I connect the txd to the RTS and the rxd to DTR or vice versa?

[yesyes]

Ah, no. It may have been a bit late last night when I replied. While TTL levels are fine, you *do* need an adapter that actually has DTR and RTS status lines. This one on Amazon only has the RxD and TxD data lines which are not used with this mod.

[CedricTheBrave]

ah ok gotchya.

thanks for the swift response

[CedricTheBrave]

Ok, this looks sorted now quite enjoyed going back to my roots and hacking stuff around its been great fun and thanks for all the info.

One question remains is how do I test the functionality?

It all looks like its working ok but I have no idea what I am supposed to be seeing

[kipstar]

sorry to bother you mate but would this work with the toucam pro ii its flashed to the spc900 nc frameware so the chips are the same are they not they just made it all smaller for the spc900 houseing i hope anyway im finding it a bit hard to find the dg418 analogue switch and this looks better for me

[yesyes]

I have no idea, I never tried that. If they use the same chips, then it might be possible. If the circuit board has a different layout, then you need to find the right places to solder your wires to.

[kipstar]

got ya im going to have a little look at it but good news is i found a dg418 analogue switch so all well thanks for the reply mate

[Leo.A]

I'm just looking into doing the serial mod on my flashed SPC880 and I have a few questions (hope this thread is still current).

First stupid question (sorry if it's covered in the 38 pages, I haven't had time to read them all), has anyone used peltier cooling with this mod/cam?

I have some 40mm peltier coolers and was contemplating using one to cool the sensor. I've been told condensation can be a problem if I run a cold finger from the peltier to the sensor (rear) and figured it would probably affect other curcuitry.

I'm toying with the ridiculous  idea of using a small cpu heatsink assembly on the rear of a peltier and having a small PC type fan blowing past the cold side of the peltier into the jiffy case I'll be using. I also purchased a controller to adjust the temp of the peltier but doubt it will fit in the case (I'm going to need a shoe box, size 11 at least, lol). I've drawn up a rough design of a small funnel type device with the peltier mounted vertically below the case (cam case) on the side of the funnel and a fan drawing air in from the base. The idea is the air will cool sufficiently as it passes the peltier and have sufficient force to blow up into the cam case and exit small vent holes. With this idea I could also direct the air easily to cool other components in the box.

I've purchased a 40mm adjustable speed ball bearing fan for the design.

Another thought, if I use an alloy jiffy cases and mount the peltier directly on the case, would that also cause condensation inside the case?

If I mounted it a small distance from the alloy case with holes would the peltier provide sufficient cooling by chilling the entire case slightly without the need of an extra fan?

I may need a fan on the heatsink, hopefully not.

The same circuit I see everywhere from Yes-Yes lists the diodes as 2N4148 which list as triacs in all the references I could find. I've assumed they're 1N4148 diodes.

I've purchase pin header bars (male and female) from China via ebay to minimize my need to solder directly onto the cam board. Everything except Q3 will be a plugged connection. This will aslo save me from having to cut/break off any pins or bend and file the pins/socket. I've even ordered 50 pin units with 1.27mm pitch to replace the original USB connector. I only have to cut it down to 6 pins.

Now to the tricky question:

Q3 has a very small solder point and with chronic migraines every day and ever failing eyesight I'm hesitant to want to solder directly to Q3 if I can avoid it. I checked with my multimeter and found a few points which  connect directly to Q3 but they are just as tiny.

If I solder to Q3 is there any unused point on the sensor board with no connection I could perhaps solder a small pin onto then use a plug type connection from the base of Q3 to the zener diode?

I'd still have to run from Q3 to the pin via a soldered joint but since I'm likely to do these mods in stages (health issues) I don't want to risklifting Q3's solder pad.

I may drill a small hole in the sensor board on the front edge (opposite cut out on second board) and use a small screw in pin.

Due to my my lack of necessary parts at home, I won't be able to start till all my goodies arrive and won't know what size case will be required till I get all the boards sorted.

I'm contemplating running the boards separately instead of plugging them back together via the 20 pin connector (I purchased these from Hong Kong, should be here in 3-4 weeks). I think if I make small cables running tbetween boards instead of soldering everthing, there's less chance of messing up.

I probably have all the necessary parts on old boards (my old washing machine circuit boards have the diodes and BC547 transistors) but decided I'd do this once and not mess up since these cams are now near impossible to locate, other than from France (Ebay) for $120++ (excluding $40 freight to Aus) for a non modded, used item.

Hind sight would have been great, I paid around $120 new, flashed to the 900 from a UK ebay seller and this included the nose cone. I should have purchased a few, I'd be able to get $200+ now for them here....

Is there a known replacement cam which substitutes for this in CCD quality/low light capacity?

I have a few friends intersted in trying cam astrophotography after seeing some of my moon and planetary shots.

Once I get started I'll likely post a few shots of my own take on the mods ( big thanks to Yes-Yes) and hope I won't require a forklift to lift the cam to the focuser (I always over engineer, even simple electronics).

A big thanks to the input of everyone here, some I've read and many I'm yet to read.

The night is young and my reading glasses are clean, all I need now is a bucket of coffee....

[Leo.A]

What ever happened to the ability to edit our previous post?

I forgot the main thing I'd like to know:

Is there a circuit diagram (schematic) for this cam available anywhere?

[yesyes]

I can't say much about the peltier. I've not tried this with a webcam and I can't remember reading about anyone else trying. (though I'm sure someone must have tried)

I'd recommend reading up a bit more on peltiers as some of what you wrote doesn't sound right. For one you will definitely need to put a heat sink and most likely a fan on the hot side of the peltier. And I'm not sure blowing air past the cold side will cool it enough.

But I can answer some of you other questions.

>> The same circuit I see everywhere from Yes-Yes lists the diodes as 2N4148 which list as triacs in all the references I could find. I've assumed they're 1N4148 diodes.

Yes, sorry. It should be 1N4148. By the time I realised the typo the image had already spread quite a bit and it was too late to correct it. I hope this hasn't caused anyone any trouble.

>> I've purchase pin header bars (male and female) from China via ebay to minimize my need to solder directly onto the cam board.

I hope you bought the right size. They are smaller than the standard 0.1" / 2.54mm pitch.

>> Q3 has a very small solder point and with chronic migraines every day and ever failing eyesight I'm hesitant to want to solder directly to Q3 if I can avoid it. I checked with my multimeter and found a few points which  connect directly to Q3 but they are just as tiny.

If I solder to Q3 is there any unused point on the sensor board with no connection I could perhaps solder a small pin onto then use a plug type connection from the base of Q3 to the zener diode?

I'm not aware of any such solder points. I found soldering to the base of Q3 the trickiest part of the whole mod. I found it helpful to push the wire in between the 2 slightly bigger capacitors next to Q3 and bend the tinned end into the correct position with tweezers before soldering. It also helped to put quite a bit of flux gel onto the tinned end of the wire. See pictures on my website about 2/3 down on this page: http://www.yesyes.info/index.php/how-tos/modding-an-spc880-900-webcam-for-long-exposure/

It's also worth mentioning that this part of the mod is for amp-off, not long exposure. So if you don't do the connection to Q3, you'd still be able to do long exposures though you might get a bit of amp glow.

>> I may drill a small hole in the sensor board on the front edge (opposite cut out on second board) and use a small screw in pin.

I would strongly recommend against that. This is a multi-layer PCB and you never know what you drill into. You might short out or disconnect something on the inner layers.

>> Is there a circuit diagram (schematic) for this cam available anywhere?

Not that I'm aware of. I'd be interested in that myself. Companies just don't publish circuit diagrams of their products any more these days. Trade secrets, copyrights... ;-)