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Harry Dalek wrote:Hi Albert
Your a master of the mechanical and electrical so i know you can get it going ,i will watch the build with interest...always like picking up tips ,i know this is to hard for me very much so on the computer side of things ~!
Viewmaster wrote:Harry Dalek wrote:Hi Albert
Your a master of the mechanical and electrical so i know you can get it going ,i will watch the build with interest...always like picking up tips ,i know this is to hard for me very much so on the computer side of things ~!
Harry, with circuits I just copy someone, else I cannot do any project.
I am the electronic dunderhead of NBTV
Don't be put of by simple BBC BASIC, Harry. Just a question of IF this then THAT, ELSE something else. etc
Just simple logic although I found that fast inputting 8 bits from the old laptop printer port was a bit of a pig,
but there again, it was others on the net that steered my little ship in.
Put a BBC BASIC emulator (many are free) onto a laptop and it storms away,
much faster than on the old Beeb micro of old............ And one can have 255 x 255 x 255 colours !!
Will post here if more progress......or otherwise. Fortunately little electronics is required
for The Slow Nip.
Harry Dalek wrote:With the 360 movement i was wondering if a fine screw on a geared motor could be used some how for the vertical movement ...i like the mechanical part of this sort of stuff lots of ways to do the same thing ...i only had lego as a boy but i really wanted meccano ! making up for it now
Viewmaster wrote:Thanks for your ideas, Harry.
Rotating the laser was my first thought but due to air friction etc its top speed is limited.
I wish to get up into the upper thousands of RPM !!!
I shall mull over your induction idea though. But it looks a bit too techy for this EX gardener.
If the laser were horizontally fixed looking at the spinning mirror the true
360 degree, I MUST( ) obtain would be restricted by the laser body itself.
Angling it up or down results in a curved scan (that might be interesting!!!)
So the laser will be mounted looking DOWN on the very tiny spinning mirror which is facing up
at 45degree on the end of a vertical motor shaft.
In this way only a thin piece of steel holding the laser will obstruct 360 degree scan.
(say just 1/16 inch thick)
I have change my mind (frequently ) and will use PWM motors, not stepper.
No need for great motors speed accuracy as the laptop will be slave to scan position.
In the past I have fretted and struggled at times, as many have, to get NBTV motors to sync,
now I am not bothered. Just let 'em wander slightly and I will follow.
Ah, life of bliss at last! ...........who am I kidding?
Harry Dalek wrote:Hi Albert
Good to see a warning to others ...360 laser line and with vertical scan we are talking a laser will hit your eyes at some point in the scan.
Harry Dalek wrote:Being in another room is the way to go ...sounds like a good set up i was wondering how you were going to test it .
I rather like lasers so will be interesting to see yours work ...
Viewmaster wrote:
Depends on how high up it scans..........one could always stand on a chair.
How am I going to test it you ask, Harry. With fingers crossed and eyes tightly shut.
(I have ordered laser safety glasses)
Test in stages. First,see if I can continually detect the light changes from the subject under laser scan
especially at top speed now aiming at 20,000 RPM . The reflected laser still looks bright at 5000 at present.
I shall need a multi angle photo diode to test. Maybe a bank of them in a circle?
Any ideas, any one please?
[/quote]Any sync disk etc mounted on that shaft at of 20,000 could be real trouble.
Viewmaster wrote:Harry, lowering the laser power is a good idea.
Regarding head amp. I am no good at circuit design as I said so I am
copy and paste (!) a Jeremy Jago design I found in an old Newsletter.
Yes reflective opto encoder but that suggests me out of my shallow depth............again
I am trying to keep it all with my knowledge boundary.
I am afraid Lego is out now. I am building a more substantial rig for the very high line scan
rates and faster frame rates too. It's a pity but I consider that Lego, even super glued together
will not be up to this task.
Further about testing. I shall enclose the machine in a large tall circular box with various images
around the inside of its diameter. A bit like the inside surface of the old Zeotrope.
Maybe on old beer barrel type enclosure.
This has the advantages that the laser beam is contained and the photodiode will be
very near and so pick up a big signal.
I built a PMT a few years ago but it has been long scrapped. I might dig it out from the local landfill!
I have been looking at you excursions into PMT. If one or more diodes don't work then I may have to follow
PMT way. Unlike normal type NBTV cameras, the laser is very bright around the room even at high revs.
There's always higher power lasers, but I don't wish to have to buy a white stick on eBay.
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