Searching \ for '[OT] Galvanometers' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=galvanometers
Search entire site for: 'Galvanometers'.

Exact match. Not showing close matches.
PICList Thread
'[OT] Galvanometers'
1997\12\28@161155 by Thomas M┐rch

flavicon
face
I know this is kinda off topic, but since this is the only
hardware/software/everything list that i know of, i'll post it here....

A couple of years ago, i saw a demonstration of a DSP from Analog Devices,
wich displayed a rotating logo on a oscilloscope in X/Y mode. I have lately
been thinking about doing the same thing, but with a laser instead... It
could be fun to make a rotating (digitaly) clock display (like the opengl
screensavers that come with WinNT 4.0), that was blown up on the wall...

I was planning on using some galvanometers (if i can find some cheap)
(Someone here mentioned that there was some in a videodisc player???) And a
laser diode, for the light thing..
So my questions is:

1. Anyone got any experience with such an implementation?
2. Where do one get hold of galvanometers?
3. How fast can one turn a laser led on/off?
4. See number 1. :)

I know that it must be some kind of vectorised graphics engine in a DSP (i
don't think a PIC is fast enough for this one). But besides this i haven't
got any clues as to how i should attack this little challenge...

- Thomas

1997\12\28@173644 by Mike Keitz

picon face
On Sun, 28 Dec 1997 22:09:03 +0100 =?ISO-8859-1?Q?Thomas_M=F8rch?=
<spam_OUToz2afoTakeThisOuTspamPOST8.TELE.DK> writes:
>It
>could be fun to make a rotating (digitaly) clock display (like the
>opengl
>screensavers that come with WinNT 4.0), that was blown up on the
>wall...
>
> I was planning on using some galvanometers (if i can find some cheap)
>(Someone here mentioned that there was some in a videodisc player???)
>And a
>laser diode, for the light thing..

> 2. Where do one get hold of galvanometers?

Look for "swing motors" instead.  The pen in some types of chart
recorders (anyone remenber chart recorders) such as those used for
medical analysis was driven by one.  Most newer hard drives use one (and
a lot of feedback) to move the heads.  The hard drive motor would need a
spring added to give it some direction of where it should stay.  Also
I've heard of removing the paper cone from a loudspeaker and attaching a
mirror instead.  Driving these devices with current rather than voltage
may work better.

> 3. How fast can one turn a laser led on/off?

Very fast.  Several MHz are possible.  But, using a standard module with
the power control built in it may not operate faster than a few Hz
without modifying something.
>
>I know that it must be some kind of vectorised graphics engine in a
>DSP (i
>don't think a PIC is fast enough for this one). But besides this i
>haven't
>got any clues as to how i should attack this little challenge...
>
Early video arcade games used a vector scan monitor and obtained effects
like this using the 8-bit Von Neuman processors (Z80, 6502) that were the
style of the time.  So the AD demonstration may actually be using little
processing power, but still making an impressive demonstration.

The process generally involves computing a matrix based on the angle
position of the display, then multiplying the x,y coordinates of each
point to be displayed by it to get the screen coordinates of the rotated
image.  So a fair amount of multiplication and addition (DSP chips are
good at that) but very little trigonometry.

After the screen coordinates of each point have been computed, then it's
just a matter of computing the x and y slopes between the ones that are
to be connected with lines, and driving the display.

Rather than tackling the laser end right away, try getting it running on
an oscilloscope first.  Or, rather than trying to compute a rotating
display, try making a simple straight one first.

1997\12\28@192034 by David Lions

picon face
I saw something about this on a laser faq.   There were also a few pages I
found about students doing this at uni.  I unfortunately no longer have the
links, but try looking for a laser FAQ.

Thomas M¿rch wrote:

{Quote hidden}

1997\12\28@200927 by wwl

picon face
On Sun, 28 Dec 1997 22:09:03 +0100, you wrote:

{Quote hidden}

If you can find an OLD Philips top-loading laservision player, these
have a HeNe laser and a nice pair of voice-coil controlled mirrors.
These players can sometimes be found at hamfests etc. very cheap.
    ____                                                           ____
  _/ L_/  Mike Harrison / White Wing Logic / .....wwlKILLspamspam@spam@netcomuk.co.uk  _/ L_/
_/ W_/  Hardware & Software design / PCB Design / Consultancy  _/ W_/
/_W_/  Industrial / Computer Peripherals / Hazardous Area      /_W_/

1997\12\28@214305 by Bob Blick

face
flavicon
face
At 01:07 AM 12/29/97 GMT, you wrote:
>If you can find an OLD Philips top-loading laservision player, these
>have a HeNe laser and a nice pair of voice-coil controlled mirrors.
>These players can sometimes be found at hamfests etc. very cheap.

I've played with these quite a bit. The mirrors are incredibly slow. Also,
the power supply for the HeNe can't be switched on-off very quickly. They
are real fun for light shows, but not much good for vector displays.

The Pioneer disk players have similar problems.

Cheers,

Bob

http://www.bobblick.com/

1997\12\29@081236 by Thomas M┐rch

flavicon
face
----------
> From: Mike Keitz <mkeitzspamKILLspamJUNO.COM>
> To: .....PICLISTKILLspamspam.....MITVMA.MIT.EDU
> Subject: Re: [OT] Galvanometers
> Date: 28. december 1997 23:20
>
> Rather than tackling the laser end right away, try getting it running on
> an oscilloscope first.  Or, rather than trying to compute a rotating
> display, try making a simple straight one first.

I know, i know...... KISS!!!! Keep It Simple Stupid :) I easily get caried
away, when i get such an idea.....

1997\12\31@142002 by Alan King

picon face
Bob Blick wrote:

Also,
> the power supply for the HeNe can't be switched on-off very quickly. They
> are real fun for light shows, but not much good for vector displays.

Most of the systems I've seen left the laser on and used a shutter to
block the light when needed..

More... (looser matching)
- Last day of these posts
- In 1997 , 1998 only
- Today
- New search...