Comments on: Mac SE/30 audio visualizer

By: a random John

a random John — Tue, 26 Feb 2008 00:03:45 +0000

note that the following hack-a-day link seems to cover what I did 10 years ago but without the spirograph effect:

http://www.hackaday.com/2006/11/05/mac-se-30-audio-visualizer/

By: neoxide

neoxide — Sun, 12 Nov 2006 09:37:56 +0000

I if I was you, I would use a more useless compact mac like a Classic or SE. Use the SE/30 for something useful, like word-processing, or playing Brickles.

By: DeFex

DeFex — Fri, 10 Nov 2006 07:51:53 +0000

back in the day we used to make these when we were kids from old TV sets. we called them “sound to scribble”

By: andrew

andrew — Fri, 10 Nov 2006 07:23:02 +0000

#19: if you have nothing better to do than complain about how other people have nothing better to do then *you* need to reconsider your life ;)

anyway i sold the se because it was broken and i was moving and i really didn’t care about it anymore :/

By: Darkcobra

Darkcobra — Wed, 08 Nov 2006 01:43:34 +0000

I did the same thing about 15 years ago with two ancient IBM dumb terminals. The long-persistence green phosphor made for a very nice display. The cases were painted gray fleckstone, and they were a big hit at a mad-scientist themed Halloween party I hosted. I no longer have them, they were trashed one move because they were huge and weighed a ton. I tried again with a modern monitor, but I didn’t like it nearly as much without the long-persistence phosphor.

Tip: make sure you don’t run the electron gun without either the X or Y deflection running, you’ll burn the screen. there will be a blackened spot and a permanent smoke trail running up the inside.

By: Michael

Michael — Tue, 07 Nov 2006 19:06:22 +0000

If you have time at your hands do do something that useless probably you should reconsider your life…

By: neoxide

neoxide — Tue, 07 Nov 2006 08:11:07 +0000

You SOLD an SE for $1? why?

By: mattyfu

mattyfu — Tue, 07 Nov 2006 06:54:04 +0000

A drum riser made out of these is only a matter of time LOL

By: andrew

andrew — Tue, 07 Nov 2006 04:22:11 +0000

wow this is amazing!! so simple too! makes me kinda wish i hadn’t sold that broken se for 1$ in the last garage sale :)

By: ex-parrot

ex-parrot — Tue, 07 Nov 2006 03:22:15 +0000

@ #14: sure, the vacuum, the phosphorus and the sharp edges could all potentially kill a person, but concrete will kill you if you eat enough of it….

as for shooting electrons at “near light speed” – it doesn’t really use that much energy. electrons don’t exactly have a lot of mass. the voltage used to accelerate the electrons in a macintosh SE is quite high, but it’s quite low current. it probably wouldn’t be the best idea to touch it while it’s on, but once it’s been switched off it’s fairly safe very quickly. the large power filter capacitors on the analog board present more of a risk.

anyway, don’t just take my word for it, this topic has been discussed to death on places like applefritter where turning compact macs in to interesting things is practically a way of life… and of course, as always, better safe than sorry :)

By: HaX80r

HaX80r — Tue, 07 Nov 2006 02:11:01 +0000

#7:
Ha - "I doubt the CRTs in these things could kill a person". The flyback transformer in that CRT puts out 20kv. The phosphorus in the front of the screen will kill you. And, think about what you are doing in a CRT; shooting electrons at near light-speed at a piece of phosphorus and glass. That uses a lot of power. Be careful, y'all.

#6 You CAN make a CRT into an oscilloscope
http://www.angelfire.com/80s/sixmhz/tvscope.html

CRT's rock.

By: ...

... — Tue, 07 Nov 2006 01:39:46 +0000

The fact that you used rubber gloves to protect yourself against the high voltage out of a tv really disturbs me. The output from a flyback transformer can easily break through most gloves, gloves that are designed to take 30kv have a very thick layer of rubber and a layer of cotton to protect the rubber.

In any case, if it works it works ;)

As to making one into a real oscilliscope, there are a few problems. The first is that you need a time base for the x-axis. You should be able to get away with a function generator that gives a sawtooth wave feeding into an amp for that tho... But the bigger problem is that the magnetic coils are very limited in their bandwidth, being highly inductive they can't be used for more then a few hundred khz.

Although a scope made out of a big ole TV would be a great teaching tool to show classes what waves look like...

By: neoxide

neoxide — Tue, 07 Nov 2006 00:14:18 +0000

As an owner of about 10, these are the heaviest compact macs I have. Aside from that dodgy color one, they’re the most powerful too.

By: jimmy d

jimmy d — Mon, 06 Nov 2006 19:30:57 +0000

Curious if this could be applied to any sort of CRT display of the instructions are specific to just this type of Mac. Very interesting, but alas, no room for a dedicated visualizer display… I’m sticking with the ol’ software vis.

By: agent420

agent420 — Mon, 06 Nov 2006 16:35:03 +0000

I’m guessing the mac has a constant operating high voltage supply, which is somewhat unusual… Most monitors and televisions use the energy from the collapsing field in the horizontal deflection coil as a power source for the high voltage supply. In these cases, it is generally required to leave the horizontal coil attached, and move it off to the side, using another coil for your deflection.