[Tweakie]

Towards the end of last year I decided to construct a controller for my Synrad RF laser as an alternative to using the UC2000. Nothing High-Tec just real basic stuff. Extensive testing over the winter months has shown that the MKI is now ‘good to go’ and so far at least 3 other units have been built, by others, in different parts of the world, with no bad reports having been received so far.
This is an ‘open source’ project and still has some way to go before it is finalised but full constructional details of the prototype including the pcb isolation routing GCode and PIC hex files are available on my website here. RF Laser

Tweakie.

[cinematic2]

Hi Tweakie
Don`t have one controller for sell?
Mayby you can make next one better and sell this one :-)

Regards
Wojciech

[Tweakie]

Hi Wojciech,

I went to all this trouble especially for you, so that you could make your own controller

Tweakie.

[Tweakie]

The enclosure for this little project has now been completed.

Tweakie.

[zax15uk]

Nice job Tweakie, that's very slick.

Zax.

[Tweakie]

Thanks Zax.

A 1 second blast at 20.5% (no lens, beam diameter approx. 6mm on target at 450mm from laser) just for fun.

Tweakie.

[northerncalguy]

Hi Tweakie - I am trying to make the controller and was hoping you could share the ASM source code and any construction tips? I attempted to get this working with a protoboard, but no luck so far. Do you have a recommendation on how best to check that the PIC program took properly?

In your schematic, you show a XTAL -- what type and frequency did you use? I tried to create my own bill of materials from your schematic and got them from Mouser here in the states...don't know if I missed something totally basic.

This project is probably more advanced than I can handle, but I have all the parts, just need a little more guidance to get it over the line!

[Tweakie]

Hi Northerncalguy,

Most PIC programmer software allows code verification after writing – this way the programmed code is read back and compared for error with the original hex file.
The Xtal I used was 20Mhz (sorry that was not mentioned in the info).
There are no special build or setting up requirements so it should work without problems but I recommend that you use the PCB shown in the zip file.

Tweakie.

[northerncalguy]

Awesome, my latest batch of Mouser components includes a 20Mhz crystal. I have actually fab'd your PCB already so just waiting to get the drill bits to do the holes then it's on to soldering.

If you're curious about how I setup the optics with my Synrad, I can share those thoughts with you...unless you've already done so . See attached image of my mount. You can't see the internals, but there will be a 10mm ZnSe window behind that aperture and a 0.5" ZnSe 1" FL lens behind that. I also have an air assist hole bored on the opposite side. Hope it works .

https://docs.google.com/file/d/0B8_G...hvZWZCXzA/edit

[Tweakie]

Hi Northerncalguy,

You may find that placing the focus lens that close to the laser source will limit it's ability to produce the smallest possible dot size.
Perhaps worth checking with the Synrad data sheets for the exact information but, from memory, I think there is a minimum recommended distance (possibly 1 Metre).

Looks like a nice job you have made of that nozzle perhaps the best thing is just to try it and see.

Tweakie.

nb. If you are thinking about mounting the Synrad vertically then you may have problems.
Again check the Synrad data sheets for the exact information but CO2 lasers, in general, produce molecular sized debris during operation and these particles will land on the output coupler causing localised heating of this component which ultimately leads to early failure.
Synrad refuse warranty for new tubes which are mounted more than a defined angle from the horizontal for just this reason.

[northerncalguy]

Tweakie - I've managed to get most of the board populated and during soldering, I quickly realized that the board layout you provided + the Gcode was designed for the isolation milling method you noted. Since I used the traditional photo etching process, I'm left to wonder about where all the individual grounding points are.

Did you tie all the ground points to 0 VDC, per your schematic? I am thinking of attaching a grounding buss but not sure if this will cause any issues with the rest of the circuit.

If you could post or PM me a high resolution image of the routed PCB that would help tremendously!

I am about 80% there, going to power it on pretty soon and start scoping to see if the signal is as expected.

[Tweakie]

Does this help ?

Tweakie.

[northerncalguy]

Yes, it does -- I finished the grounding, programmed the PIC and powered it all up but it's not alive . Obviously...something went wrong during the execution and I am trying to trace it through. Do you have any thoughts on where mistakes could be?

Here's the circuit:https://docs.google.com/file/d/0B8_G...it?usp=sharing

The front of the unit: https://docs.google.com/file/d/0B8_G...it?usp=sharing

According to your notes, the unit is controlled entirely with the rotary encoder and integrated push button, correct? So just ignore the two little pink lines - they run to momentary switches, but I haven't wired the resistors to them yet.

This is the encoder I used: PEC11-4215K-S0024 Bourns | Mouser

I tried to scope the output and various points on the circuit...nothing other than a 60hz sine wave .

[Tweakie]

Can't see anything obviously wrong. Are you powering it from 9Vdc and have the polarity correct ?

Tweakie.

[northerncalguy]

Yes, power is working correctly - I have a bench supply feeding at about 10V within the spec of the regulator. That shows a correct output of 4.99v to the rest of the circuit. The LED backlight for the display, also up and running.

[Tweakie]

OK, I had to suggest the most basic thing first, sorry.

The next step is perhaps to re-check you PIC programming...

Check Programmer software is set to 16F627

Fuses; The PIC will not function at 20MHz unless the Oscillator has been set to HS (high speed) at program time.

Tweakie.

[Gr6Burns]

The LED backlight for the display, also up and running.

[northerncalguy]

Looks like those settings got me one step closer; now I see some text on the display, but garbled. This is after each detent on the encoder wheel...the button push apparently has no effect.

Scoping the output still shows up empty.

https://docs.google.com/file/d/0B8_G...it?usp=sharing
https://docs.google.com/file/d/0B8_G...it?usp=sharing
https://docs.google.com/file/d/0B8_G...it?usp=sharing
https://docs.google.com/file/d/0B8_G...it?usp=sharing
https://docs.google.com/file/d/0B8_G...it?usp=sharing
https://docs.google.com/file/d/0B8_G...it?usp=sharing

I believe the LCD display is correctly wired as it is based off the HD44870 per your spec:
http://www.mikroe.com/eng/downloads/..._2x16_spec.pdf

So close I can feel the laser pulses nearby!!!

[Tweakie]

Just a thought, but try reprogramming the PIC to use it’s own internal oscillator and see if that then produces the correct display. Overall it will not be running fast enough for laser control but it may serve to indicate that you have a problem with your 20MHz crystal.

Tweakie.

[northerncalguy]

It's alive!! Sort of...I'm puzzled by two things:

1) Why is the new crystal not working? It's a standard one made by ECS. I've another I can swap out though.
2) Even with the internal oscillator, I should be getting some type of pulse at PWM output pin, right? Scope there still shows a lonely 60hz signal...do I have a fundamental wiring error or scoping error?

https://docs.google.com/file/d/0B8_G...it?usp=sharing

Thanks so much for walking me through and being generous with your time thus far