A 'blast from the past' just for fun

[JasonB]

Hi all,

14 Years ago as a broke college student I was so jazzed up about scanning that I purchased a $150 kit via mail order from SVS (Silicon Valley Servo). Now the technology was old compared to todays standards and the cost represented 25% of of my net worth but being a solder slinger and loving lasers I could not resist!

Check it out. This kit from 1993 used a scanner built a with rare earth magnets and a simple flag on each motor that was an IR emitter/receiver for closed loop 'PID control' position feedback. But looking back on the schematic now we realize each axis was only 2 bits and the DAC was designed using NAND gates! (see schematic). Frequency response was slow with a max deflection angle of 16 degrees but it actually did draw some animations when set up with patience (required an o'scope to balance the amp). And when the feedback signal faulted due to ambient light sometimes the motor would run away ejecting the first surface mirror from the shaft....

At any rate thought it would be nostalgic to share this - used a 1 mW laser tube bought at a hamfest along with a laser power supply kit from MWK electronics I think... The laser power supply uses a 555 timer for an oscillator, step up transformers and voltage multiplier. And I was geeky enough to replace burnt out components when they failed (usually a HV cap or the current limiting HV resistor); and the tube is mounted poorly in an old gutted telescope housing because the laser was built on a shoestring budget from saving money mowing lawns in high school. This old laser still works!

And now discovering these new diode pumped lasers... Cool! The RGB laser setups with blanking look very exciting when used with Popelscan, etc...

The purpose of this post is to introduce myself and share a bit of history because discovering this forum re-ignited an interest in scanning and lasers - now its time to build a real DAC and get a new scanner... A Simple 8 bit DAC driven via the old LPT port or maybe something like the Unix based bilda Laser project over USB...

Back to history: the software used back then was written in QBASIC and wrote to the parallel port via BSAVE instruction because that was the only way to get data fast enough out of an old Windows XT/AT PC back then (Am I showing my age?)

Oh and as you might guess from the avatar I recently ran into a large laser; a 12 Watt Argon Ion by Coherent to be exact. Evidently it worked when de-commisssioned, although its near the end of life cycle. What a shame that a phase converter is required to run it at home but since I was a lad always wanted such a laser, didn't all of us? Someday maybe I'll bring it to work where 3 phase 230VAC and water utilities are available... But NOT before understanding the safety practices (eyewear especially) required to operate such an instrument.

* Whew! * what a long winded introduction of myself... My name is Jason, can't wait to further explore the new advances in the hobby sector of this technology and share ideas on this forum!

[300EVIL]

Hey Jason!
Welcome to PL! Great story! I basically started around the same time, the same way. Back in the day, a 1mW He-Ne was pretty damn cool! It still is but,,,, MORE POWER!
I'm sure you'll have a blast getting back into the hobby, I know I sure am. Lasers and galvos are cheaper than ever but you'll probably get crazy like everyone here and eventually turn it into your new money pit. Totally worth it though.

If your interested in a simple DAC, I make this kit... http://www.photonlexicon.com/forums/...-Buy-Edition.?

Again, Welcome to PL!
Adam

[Lazerjock]

Welcome Jason,
I had the exact same scanner setup. I remember the scanner mounts were made of plexiglass. I had big plans for that system, then I came across a much better system that ran on an Apple IIe with a digitizing tablet and G125 open loop scanners and no blanking. Later I designed my own mechanical blanking system by adding another scanner and amp. It worked well for what it was. I still have a video of one of my shows. It had a beam projector the main scanners, strobes, police lights, and black lights. All of it was run manually. Cool stuff in the early 90's. One of these days I will have to post it on You Tube.

Hopefully you will be able to make it to one of the LEM's (Laser Enthusiasts Meetings). SELEM would be the one to goto if you can make it.

Chris

[JasonB]

Built a quick breadboard circuit to verify that data is valid on the parallel port! Of course the software (Popelscan for now) is good so its more like a test to be sure wiring is OK. Used a 7404 inverter to interface with the parallel port to illuminate LEDs for verification that software is writing to parallel port address; looks great. Yeah I know I'm behind the times but the cool factor is stepped up a bit considering that I borrowed a 7404 from my senior design project from 10+ years ago that was a color organ looking at music to drive flood lights.... Aint we all the same? No need for USB control yet.

Next step is to route parallel port data to DAC ==> for scanner XY reference... Then will piggy back on the data to get RGB modulation Eventually...

Not sure I made the right choicel put an order into midwest laser for a 20Khz (yeah 30 KHz would be better) scanner and have not heard much back from vendor regarding delivery....

[kecked]

I started into laser from that kit. Before that it was hene off mirror on speaker. I thought I was in heaven when I built their function generator. I remember the solvent to glue up the fluorescent pink plastic and cutting the paper tag for the scanner. It was fun and I loved it. I wish I knew where mine ended up. It would have been interested to driver it from my qm2K and see what kind of scan rate it actually could do. I never got around to doing the dac.

[mophead]

Welcome to PL, Jason.

Cool old project, thanks for sharing. You really need to try to make it to SELEM this year. It will blow you away.

[megaton]

Hi Jason

I remember when I try to run the Qbasic.
And just run on a 286 or 386.(486 no way, very fast).
My SVS still running in my living room with my first Lunch box DAC and a wood Laser table.

If you need the software I still have it.

Cheers,
Ed

[Retina Burn]

LOL,,I still have my SVS packed up somewhere

[JasonB]

Hi All,

Since the USB sound card is on order to get in the (21st century) I could not wait so the Popelscan LPT-RGB interface is breadboarded! If ya can remember this far back Its got 2 A/D ICs and a latch to output the RGB, all off the 8-bit data bus.

Using mylogic probe I see the clock signals coming in OK for the DACS (LPT pin 17 to Write pins on DACS) but there is No clock on pin 17 for the RBG... I did homework and read on this forum that the 'Switch-PCB' must be enabled for pin 17 to come alive but that did not work for me. Running Popelscan 3.1x...

ANY insight would be appreciated! And yes you may flame me for using popelscan but there is a certain beauty in breadboarding (old) circuits .... Took quite a while to cross-reference some of C430's components for his LD driver from the European standards to USA ... But that does not matter yet as we gotta get the TTL signals working first.

Thanks guys,
Jason

[flecom]

I had that same SVS kit... never did get it to work right... didnt have the dac, just the oscillator kit