SPC900 LXmod yesyes style ;-)

[fwm891]

Hi YesYes,

the USB to RS232 Cable Adaptor with PL2303+PL211 Chipset has finished on ebay and the seller doesn't seem to be contactable - are there equivalents or same thing elsewhere... found this thread too late unfortunately

Francis

[fwm891]

YesYes - USB to RS232 Cable Adaptor with PL2303+PL211 Chipset - found. clearlygagets dot com (uk based) sell them (ordered 2 just in case!) francis

[Gina]

I got two while I was at it. Only used one so far but I will be doing the mod on another SPC900.

[michael8554]

Hi All

Way back in post 54 18th July Pete_1 suggested that many 232 converters put out TTL levels and that a much simpler circuit for the SC mods could be used. Subsequent posts seem to confirm the TTL bit but no-one has posted a new circuit yet.

Anyone out there got the know-how to do this please?

Cheers

Michael

[yesyes]

as far as I can tell (somebody confirm please) you could just leave out the diodes if you are sure your serial port has TTL levels (i.e. you would never get a negative voltage from the serial port).

[G6RAR]

Hi,

YesYes is perfectly correct in that you can remove the 1N4148 diodes if you are sure the interface unit gives TTL levels, without having any undue affect.

In fact, even if the levels were at RS232 +- 5V (or more) the LX control would still work as the NPN transistors would be driven hard OFF as the base voltage passed through 0V.

The diodes are there for full isolation and of course peace of mind.

As stated above.

18th July Pete_1 suggested that many 232 converters put out TTL levels and that a much simpler circuit for the SC mods could be used.

I really don't think that the circuit could be made any more simpler than it is.

Pete_1 also stated that he had made this modification and that it worked.

It would be interesting to see how this was achieved.

You coulld, in theory, take out the 1st transistor as it functions as an inverter for the input to the second transistor which is the switch for the LX mod.

Then invert in the software.

Just my thoughts

Dave

[Gina]

You coulld, in theory, take out the 1st transistor as it functions as an inverter for the input to the second transistor which is the switch for the LX mod.

Then invert in the software.

I think a problem with that might be the reset state - the state the interface line would be before the software were started up. Not sure if this matters or not - I haven't yet gone into the details.

[yesyes]

I think a problem with that might be the reset state - the state the interface line would be before the software were started up. Not sure if this matters or not - I haven't yet gone into the details.

The webcam would probably end up taking one looooooong exposure until you start the capture software. But then it should be fine... The long exposure might heat up the sensor though...

I think it's not worth saving on one transistor and one resistor. They come in 10 packs or so anyway....

[G6RAR]

Totally agree with your comments.

I was really emphasing the fact that it would be difficult to make the circuit simpler.

As they say, if it's working well why try to fix it.

Cheers

Dave

[MisterBill]

Originally I just wanted to point out that under voltages less than 12 the Zener was simply acting as a thyristor.

As soon as an RS232 signal deviates from the Standard it can pretty much be set to whatever the circuit designer wants. I would never trust a circuit that is said to be RS232 to be at true TTL specs, because it doesn't have to be. It might be, but it doesn't have to be.

For my peace of mind I am leaving all the diodes in place when I build my board. I might, however, replace them with Schottky diodes to take advantage of the lower voltage drop.

YesYes, if you are going to design a new circuit you might want to use the MAX232A (actually MAX232ACPE is the full part) because it requires only .1uF capacitors. The original MAX232 required 4.7 and 10uF capacitors, which are bigger and cost more. There is a chip in that family that has everything onboard, but is rather costly compared to these.

Back to the honey-do list.

Bill

[yesyes]

Originally I just wanted to point out that under voltages less than 12 the Zener was simply acting as a thyristor.

As soon as an RS232 signal deviates from the Standard it can pretty much be set to whatever the circuit designer wants. I would never trust a circuit that is said to be RS232 to be at true TTL specs, because it doesn't have to be. It might be, but it doesn't have to be.

For my peace of mind I am leaving all the diodes in place when I build my board. I might, however, replace them with Schottky diodes to take advantage of the lower voltage drop.

YesYes, if you are going to design a new circuit you might want to use the MAX232A (actually MAX232ACPE is the full part) because it requires only .1uF capacitors. The original MAX232 required 4.7 and 10uF capacitors, which are bigger and cost more. There is a chip in that family that has everything onboard, but is rather costly compared to these.

Back to the honey-do list.

Bill

I totally agree. You never know what you get from the serial port. The specs are a bit wishy-washy. The diodes are so cheap that there really is no point leaving them out.

Regarding the MAX, since I have a 12V power supply (this has nothing to to with the webcam) I prefer using the MAX231. The MAX231 is the same as the 232 without the 5V to 12V charge pump but requires a separate 12V supply. There is no point regulating down the 12V to 5V only to have the MAX232 to pump it up to 12V again. It also saves a few capacitors.

[fwm891]

Yesyes, I'm getting bits together to have-a-go at this. Looking at the extra images on your link I see on the USB board (left hand side) that where the four sets of cables enter they dont (colour wise) necessarily go to the same pad designations on the board i.e. there are red & black on the +5 volt pads ditto on grnd. Also whit & green seem to mix on the DP & DM pads.

Can I ignore these crossovers once the board is stripped or do I need to note there positions for later (I'm guessing not but want to check) Ta.

Francis

[Gina]

That's odd Francis, yours is different from mine. Mine had alternate green and white wires. Which corresponded to the board markings. Another strange thing - on yours there seems to be a black wire soldered onto the +5v pad.

[yesyes]

Yes, I found this weird as well (this appears to be a picture of one of the hubs I used). The left USB-out cable seems to have been wired with the colours mixed up. The labelling on the hub PCB is correct. So go with that.

[MisterBill]

Mine has 4 sets of RWGB and it looks like one of the electrolitics was replaced. Oh well, as long as it passed thier stringent QC......Where is the "rolling the eyes Smiley" when I need one.

BTW, how in the world does one solder to the Base of Q3? At 67 between the shakes and the eyesight I barely did the PINS/PADS. Took the power for the LX board from the large pads on the USB/SERIAL board.

Other than Q3 I'm ready to go.

Bill

EDIT: Just took care of Q3.

I made an L shaped jig from perfboard taped it in place over Q3. I then used one of the jumperwires from a modular phoneline coupler I had. These jumpers have stiff wires on the ends. I just added a heatsink to the end of the wire near the crimped end, heated and tinned the stiff wire. Held it up against the jig and slid it down on to the Base of Q3. Held it in place until the solder cooled.

I'm glad I don't have to do this for a living.

Bill

[Gina]

I have problems seeing tiny stuff too - my eyesight isn't what it was (I'm a couple of years older than you). I make use of all the aids... "helping hands", large magnifier with ring light round it. And to see really fine things like surface mount chips, I have a 6x magnifying glass.

[fwm891]

Yesyes - thanks it is your image I copied it from your link - just performed surgery on mine and the connections are paired not as in photo. Just a lot of hot-glue smothered over each end...

Well not (quite) as old as Gina and Bill so there might be hope for me

Is there an OAP section !

Francis

[NickRose2006]

I got this warning while installing the USB/Serial adapter, of this software has not passed the Windows Log test. Has anyone gotten this before? Is it safe to install?

[yesyes]

Yes, that should be fine. They just couldn't be bothered to pay Microsoft for the certificate.

[RogerTheDodger]

That just means it's an unsigned driver, I was happy to install it and have had no problems - this doesn't guarantee anything though

[Gina]

I've installed lots of software without certificates without any problems. But just be careful what you do install and run a virus scan before using it if possible.

[NickRose2006]

Would it be possible to do the same type of setup with the Toucam 740? When I say same setup I mean with everything from the LX/Amp off board to the USB Hub. I know looking at the modes for the 740 it is totally different.

[NickRose2006]

I've installed lots of software without certificates without any problems. But just be careful what you do install and run a virus scan before using it if possible.

It seems like I might need to reinstall my operating system and everything else, because now my webcam is not being recognized by the computer. I'll have to check on in tomorrow morning since its almost bed time for me right now.

[MisterBill]

Do not reinstall your OS. It looks like a lot has transpired between your last 2 posts.

Give us more information. What is your OS? What changes did you try to make?

Bill

[Gina]

It seems like I might need to reinstall my operating system and everything else, because now my webcam is not being recognized by the computer. I'll have to check on in tomorrow morning since its almost bed time for me right now.

I've lost count of how many times I've reinstalled operating systems though I've never had to on the Mac. For that matter I've never needed to reinstall Linux just reinstalled to upgrade. Windows isn't so good. Have you tried a System Restore? I've often needed to do that and it's fixed a problem.

It's a good idea to keep your data on a separate partition then you can just format the OS partition and reinstall the OS without touching your data. Even so, back up first. Plenty of known good backups are always a good idea, of course.