SPC900 LXmod yesyes style ;-)

[beamish]

Following all this as carefully as an electronics numpty could with the intention of "having a go" when we get back from hols- good one guys keep it all comin'

[NickRose2006]

Well it just took 2 days to get all my parts ready for pickup, so I'll pick up all the parts today and then I have to wait for the guy in Phoenix to ship the webcam. Since I have never done soldering before, I think tomorrow I will test my skills of soldering on some old PCB boards from an old computer and then I will work on the long exposure/Amp off PCB board while I wait for the cam to arrive.

[G6RAR]

Hi Nick,

I would recommend that you use 60/40 solder, flux cored of course.

Try to avoid the "Lead Free" type.

Also, a 'solder sucker' would be useful.

A wet sponge is very useful for keeping the soldering iron tip clean.

Good luck

Dave

[NickRose2006]

Hi Nick,

I would recommend that you use 60/40 solder, flux cored of course.

Try to avoid the "Lead Free" type.

Also, a 'solder sucker' would be useful.

A wet sponge is very useful for keeping the soldering iron tip clean.

Good luck

Dave

That's exactly what I got of the 60/40 solder with a Rosin core. But I did not go for the solder sucker, instead I went for just the desoldering braid. I also got a third hand to make everything easier.

[NickRose2006]

What tool do you use to make the cuts on the back of the PCB where the copper is?

[Gina]

I have a tool produced for the job that I've had for donkey's years. It consists of a straight fluted drill bit in a plastic handle. The drill is a bit wider than the copper strip and makes a neat job without touching the adjacent strip. You could make one up from a standard drill bit of about 3mm diameter and stick it in a wooden file handle. Or make a hole in the end of a piece of dowel of say 12mm diameter.

[starship trooper]

You can get them from maplins and the like

[NickRose2006]

Just want to make sure of 1 thing with the PCB board. In the picture of yesyes I put a line to two areas, are these cuts to the copper or not?

[yesyes]

Yes, they are cuts.

And as you can see I just use a small standing knife to make the cuts. It allows me to make a cut between 2 holes. The drill bit method is only good for making cuts at a hole position. Occasionally that helps to make the PCB smaller.

[MisterBill]

I see the Prolific PL-2303 is only USB 1.1. Is that really fast enough?

[yesyes]

It doesn't need to be fast at all. We are only using the status lines of the serial port. The image/video data from the webcam does not go through the serial port.

[MisterBill]

It doesn't need to be fast at all. We are only using the status lines of the serial port. The image/video data from the webcam does not go through the serial port.

Thank you.

Bill

[MisterBill]

Great project, thanks for all the work put in on it.

The 11 volt Zener is left over from the original circuit where he was going to a serial port on his computer. This circuit is all USB voltages, 5.2v max. The Zener is only passing USB voltages, minus .7v for the voltage drop through the diode. I might remove the diode and put a 10 turn micro pot in it's place.

When my camera makes it to me from across the pond I'll let you know of the difference.

Bill

[G6RAR]

Bill,

Don't forget that the majority of USB to RS232 convertors have an "onboard" level shifter that converts the 5v USB signals to +- 12v RS232 levels (typical levels as used by FTDI and also Prolific).

Hence the need for the 'buffer' transistors on the control lines.

Wouldn't want you to blatter the camera.

Cheers

Dave

[MisterBill]

Hello Dave,

I went from the PL2303 Datasheet:

VDD_232:

RS-232 VDD. The RS-232 output signals (Pin 1 ~ Pin 3) are

designed for 5V, 3.3V or 3V operation. VDD_232 should be

connected to the same power level of the RS-232 interface.

(The RS-232 input signals are always 5V~3V tolerant.)

But I could be wrong. Thanks for the heads up.

I will stick a meter on it before I try anthing else.

I guess I could tap in at the pins for my voltage. Then I could redesign the LX Amp Off board and thennn....

Or, I could just leave the Zener alone and enjoy it right out of the box.

73 de N4RN

Bill

[G6RAR]

Bill,

You are correct. That model is 3.3 or 5v on the outputs.

There are also a few FTDI versions that have the same options.

I'm using FTDI UM232R modules for a couple of projects as they give 3.3 or 5v for direct connection into TTL or CMOS.

I've got to congratulate YesYes for starting this thread as it opens up the possibilities of creating the single cable connection to the SPC900 LX webcam. USB ports are sometimes at a premium and anything that reduces the cable count must be a good thing.

Cheers

Dave

[yesyes]

hmmmm, that is an interesting subject about serial port levels.

I have a spare FTDI FT232BM based USB to serial converter that I was going to use to control my mount. The specs for the mount (GC5-GT) say that it requires RS232 levels, so positive and negative voltages, rather than 0V and 5V/3.3V TTL levels. But according to the data sheet the FT232BM provides 5V or 3.3V levels.

I guess I need to build another converter circuit based on the MAX 231 to convert from TTL to RS232 levels...

[G6RAR]

Hi YesYes,

Sorry to throw you into a bit of a dilema.

Have had a look at FTDI site and they do indeed state that the FT232BM is 3.3 or 5v.

Do you think that this is just about the FT232 chip itself?

When it's fitted into a RS232 converter it may well have the necessary level shifter built in.

Just a thought.

I've just checked a Prolific USB - 232 adapter on the 'scope and the levels are +-5v

Cheers

Dave

[G6RAR]

YesYes,

Just checked again on the scope and the "accurate" measurement is RTS PK - PK = 13.4V +- 6.7V

DTR PK - PK = 12.2V +- 6.1V

Note to Bill over there in Florida.

When I checked the above I noted that the Prolific device is a 2303.

So again it looks as though the level shifter has been included.

Cheers

Dave

[Gina]

I've just checked a Prolific USB - 232 adapter on the 'scope and the levels are +-5v

That's interesting - thank you

[yesyes]

Interesting. Thanks for that.

I have just put the FTDI on the oscilloscope. The Tx levels is 0V and 5V. Hmmmm

You say the Prolific PL2303 has proper RS232 levels? In that case I rather buy another 2303 and have it all on one small PCB. On the other hand I still have a hand full of MAX231's....

[G6RAR]

As I said, sorry about the dilema.

But as they say, "A Max232 in the hand is worth......"

[yesyes]

Don't be sorry, I have to thank you for pointing it out... ;-)

[G6RAR]

Also, I have a number of different FTDI devices, USB to 232 and they are all 0 - 3.3V or 5V

UM232R, MM232R and I am testing a FT2232HQ

[MisterBill]

I didn't mean to open a can of worms.

Royal Mail arrived today, so my camera is here. UPS also dropped off a couple of boxes. Everything looks smaller than I expected. I just might be able to stuff it all in a Cookbook camera body a friend turned out for me back in the mid '90s. I don't believe there are too many of those "UPGRADED" to SPC900 specs. Now I'm going to have to install a relay to switch the LX in and out.

Good night all.

Bill