6 ms·

Ive done a fair bit of electronic design over the years (professionally). The classic parts are still going strong. There are even single gate devices now in SM

by pling 12y ago

Ive done a fair bit of electronic design over the years (professionally). The classic parts are still going strong. There are even single gate devices now in SMD packages! Outside the world of computing and mainstream consumer tech I expect to see our friendly TTL devices and op amps etc and even discrete transistors live another 500 years or so. Some problems are quite cheap and simple to solve with them and they're well understood. (I'm building a laser harp completely out of discretes, logic and analogue components at the moment - not a single microcontroller or CPU in sight. Even hardware MIDI :)

jacquesm 12y ago
Please, please, pretty please, document your building of the laser harp and do a write up. That's a thing that I've always wanted to do since I saw JMJ, it's an absolutely incredible concept and a nice DIY write-up would really make my day.
- pling 12y ago
  I had the same inspiration :) I'll document it when complete and submit to hackaday.com. There have been many dead ends so far so I'll probably just depress myself if I write it up before I'm done :) My objective is a parts cost of less than £100 and no programming of devices required.
ChuckMcM 12y ago
That is pretty awesome! By 'hardware MIDI' I'm guessing you're triggering a shift register which dumps its contents? Do you do after touch effects?
- pling 12y ago
  That's basically it yes. Well there's no way to apply aftertouch to a laser harp nor is there velocity so it'll be hard coded velocity (might have a pedal control in future). At the moment it will just sent note on and off down the wire. It does this using three shift registers (74LS165) and some extra bits for start/stop bits. I've got it sending notes to my Triton so far which is as far as it has got. The harp front end works with one note as I don't have a laser galvanometer at the moment (will build one). I imagine it'll take another 6 months yet at this rate. Plus I keep getting distracted playing with the nice green laser I bought :)
  - ChuckMcM 12y ago
    Oh cool, that makes sense. I got a cheap pair of laser galvos off Ebay a while ago (ok long time ago) and built a simple epicycloid generator with them and a Parallax Propeller chip [1]. It was pretty trivial to work with, send it a voltage and poof the galvos moved. [1] https://www.youtube.com/watch?v=wlc0lzUpPsw https://www.youtube.com/watch?v=wlc0lzUpPsw
    - pling 12y ago
      Cool stuff. Much cooler than doing it with a scope and function generators! I looked at galvos on eBay but I felt like I was cheating. I tried using mirror on a stepper motor shaft initially as a test but the scan rate was abysmal and it was a £3 stepper so it vibrated the bearings loose. Ended up widlerising it. I have a pile of DVD drives ready to be recycled though. They have the shafts, bearings, magnets and coils to make a galvo with. Plus some more lasers to play with. Current galvo ideas are based on: http://elm-chan.org/works/vlp/report_e.html http://elm-chan.org/works/vlp/report_e.html
paletoy 12y ago
> The classic parts are still going strong. But there are very good alternatives for them, be it low cost mcu's,50 cents fpga's, or even lower-end programmable chips from sillego[1][2]( going down to $0.2/10K + probably $0.1 more for programming - and that's without competition). Those are smaller, more reliable(less soldering) and can do quite complex functions including analog. So i wouldn't bet on simple gates holding on for 500 years. [1]http://www.eetimes.com/document.asp?doc_id=1279013 http://www.eetimes.com/document.asp?doc_id=1279013 [2]http://www.silego.com/buy/index.php?main_page=product_info&products_id=330 http://www.silego.com/buy/index.php?main_page=product_info&p...
- pling 12y ago
  Low cost MCUs have FLASH which has a finite life. Same with FPGAs which need to have their brains filled from something. I worked on a project a few years ago that had a PIC part. They never got the software working right so we looked at the original spec. The entire software could be crunched down to 7 gates and a comparator. So we did a rev2 board with a flip flop and a NAND and a LM358N and there hasn't been a failure since. To be honest with some bastardising to get hysteresis out if a 555 and a couple of transistors would have done as well. The BOM was £0.09 more expensive but the part never failed in production. The most interesting thing is that PIC part no longer exists so there is no service option other than replace which costs more down the line. (This was a watchdog monitor for signalling systems) Edit: yes I know the 358 isn't a comparator but it was fed just before saturation to get hysteresis avoiding more parts.
  - paletoy 12y ago
    Those are important considerations , but: You did the design a few years ago, before the silego was a good option. But for many design , esp in consumer , the silego part would be a good fit because it would work as same as discrete parts,it's manufacturing life and reliability(12 years) would be good enough, and it would be better in other parameters. And once the consumer market is taken, we might see versions targeted at more demanding applications. But it's not certain.
    - 12y ago

by pling 12y ago

jacquesm 12y ago

Please, please, pretty please, document your building of the laser harp and do a write up. That's a thing that I've always wanted to do since I saw JMJ, it's an absolutely incredible concept and a nice DIY write-up would really make my day.

pling 12y ago
I had the same inspiration :) I'll document it when complete and submit to hackaday.com. There have been many dead ends so far so I'll probably just depress myself if I write it up before I'm done :) My objective is a parts cost of less than £100 and no programming of devices required.

ChuckMcM 12y ago

That is pretty awesome! By 'hardware MIDI' I'm guessing you're triggering a shift register which dumps its contents? Do you do after touch effects?

pling 12y ago
That's basically it yes. Well there's no way to apply aftertouch to a laser harp nor is there velocity so it'll be hard coded velocity (might have a pedal control in future). At the moment it will just sent note on and off down the wire. It does this using three shift registers (74LS165) and some extra bits for start/stop bits. I've got it sending notes to my Triton so far which is as far as it has got. The harp front end works with one note as I don't have a laser galvanometer at the moment (will build one). I imagine it'll take another 6 months yet at this rate. Plus I keep getting distracted playing with the nice green laser I bought :)
- ChuckMcM 12y ago
  Oh cool, that makes sense. I got a cheap pair of laser galvos off Ebay a while ago (ok long time ago) and built a simple epicycloid generator with them and a Parallax Propeller chip [1]. It was pretty trivial to work with, send it a voltage and poof the galvos moved. [1] https://www.youtube.com/watch?v=wlc0lzUpPsw https://www.youtube.com/watch?v=wlc0lzUpPsw
  - pling 12y ago
    Cool stuff. Much cooler than doing it with a scope and function generators! I looked at galvos on eBay but I felt like I was cheating. I tried using mirror on a stepper motor shaft initially as a test but the scan rate was abysmal and it was a £3 stepper so it vibrated the bearings loose. Ended up widlerising it. I have a pile of DVD drives ready to be recycled though. They have the shafts, bearings, magnets and coils to make a galvo with. Plus some more lasers to play with. Current galvo ideas are based on: http://elm-chan.org/works/vlp/report_e.html http://elm-chan.org/works/vlp/report_e.html

paletoy 12y ago

> The classic parts are still going strong. But there are very good alternatives for them, be it low cost mcu's,50 cents fpga's, or even lower-end programmable chips from sillego[1][2]( going down to $0.2/10K + probably $0.1 more for programming - and that's without competition). Those are smaller, more reliable(less soldering) and can do quite complex functions including analog. So i wouldn't bet on simple gates holding on for 500 years. [1]http://www.eetimes.com/document.asp?doc_id=1279013 http://www.eetimes.com/document.asp?doc_id=1279013 [2]http://www.silego.com/buy/index.php?main_page=product_info&products_id=330 http://www.silego.com/buy/index.php?main_page=product_info&p...

pling 12y ago
Low cost MCUs have FLASH which has a finite life. Same with FPGAs which need to have their brains filled from something. I worked on a project a few years ago that had a PIC part. They never got the software working right so we looked at the original spec. The entire software could be crunched down to 7 gates and a comparator. So we did a rev2 board with a flip flop and a NAND and a LM358N and there hasn't been a failure since. To be honest with some bastardising to get hysteresis out if a 555 and a couple of transistors would have done as well. The BOM was £0.09 more expensive but the part never failed in production. The most interesting thing is that PIC part no longer exists so there is no service option other than replace which costs more down the line. (This was a watchdog monitor for signalling systems) Edit: yes I know the 358 isn't a comparator but it was fed just before saturation to get hysteresis avoiding more parts.
- paletoy 12y ago
  Those are important considerations , but: You did the design a few years ago, before the silego was a good option. But for many design , esp in consumer , the silego part would be a good fit because it would work as same as discrete parts,it's manufacturing life and reliability(12 years) would be good enough, and it would be better in other parameters. And once the consumer market is taken, we might see versions targeted at more demanding applications. But it's not certain.
  - 12y ago