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Zeus

Mon Dec 28 2009, 11:41AM

Registered Member #2316 Joined: Tue Aug 25 2009, 03:04AM
Location: Bendigo, Australia
Posts: 107

SGTC audio modulated via IGBTs on the primary side of the hv transformer. The IGBTs control the input current thus varying the spark rate. Crude but it could work.

Conundrum

Thu Jan 28 2010, 10:14PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Idea:-

build "digital analogue dmm" using 3310 screen + PIC12F683

as its already able to be backlit this should be simplez.

the idea is instead of a standard digital display the top of the screen displays multiples of 10 (i.e. 0.001, 0.01, 0.1, 1, 10, 100, 1000V) with the "altitude" of the bar above/below zero denoting polarity.

the main advantage of this method is that the display range remains constant and resolution is not lost even with high voltage inputs.

plan is to use a single channel I2C A-D and also the possibility exists of using the PIC's internal memory to store trends etc as well as the same display being useable as a scope.

also add an internal protection mechanism so out of range/negative voltages are automagically converted to prevent the A-D being toasted. One way to do this is to have the A-D externally on an optical lead (itself encased in conductive plastic) and send the signals back as different LED light wavelengths.

this approach could be useful for doing tesla coil and/or marx work.

additional ideas:- extend it to N channels by daisy chaining multiple A-D's and displaying each input as a bipolar graph at a variable position down the screen.

inspired by the similar displays on some expensive audio systems.

Andri

Fri Jan 29 2010, 06:26PM

Registered Member #1533 Joined: Wed Jun 11 2008, 02:13PM
Location: ReykjavÃk, Iceland
Posts: 46

Wearing differently coloured lenses each day, thus changing your eye-colour daily. This has the potential to perplex people around you in quite a subtle manner.

Claiming to be homosexual only on Tuesdays.

And for something more on topic: Closed loop SSTC with PWM based on an integrator with AGC. What I'm suggesting here is power controlled CW without variac.

Conundrum

Wed Feb 02 2011, 07:59AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

Idea:- in-tube laser scanner.

The idea here is that if rotating a block of glass can alter the beam path, then rotating two in
opposite directions should be able to generate a full scan.

Similar to the way a pair of spinning mirrors works, but MUCH more compact.

Just need to synchronise the rotation speeds (use a PLL) and a cheap micro to generate the required raster.

Could use a cheap salvaged fan bearing and attached magnets to spin the glass block(s) held in with baking soda and epoxy

BUT will also need to shield the windows with blutak or hotmelt to prevent them being affected by the CA.

-A

"Bother" said Pooh, as he ate the curried Gagh...

hboy007

Wed Feb 02 2011, 02:50PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374

* Build a magnetometer out of a brushless fan: rewind the coils onto a single bobbin, place the hall switch in the center and add a darlington transistor switch (single-ended drive, measures only one field direction).
Add a small permanent magnet to one side to bias the hysteresis loop of the hall switch or use a full bridge to control the coil without flux density biasing. The readout is the average over the hall switch logic level, use a simple DMM.

* build a projection microsope using only a laser pointer and a CD drive lens (and a white wall or ceiling): metal and surfaces with high reflectivity can be examined by just projecting the scattered light onto a screen.

* IR (heat) camera using a laminated foil stack: laminate an array of water droplets with diluted salt between two sheets of foil. Deposit and etch aluminium traces vertically and horizontally. Measure conductivity, capacitance, ion mobility or complex dielectric properties (whatever works) of each droplet "cell" repeatedly after sliding a peltier-cooled bar of metal along the back side of the foil. Use a NaCl lens to project an image onto the foil. Heat will integrate at different rates, delaying or accelerating the unfreezing process in respect to the average unfreezing rate. Convert the unfreezing time of each cell to a pixel gray value. (I confess this is inspired by the guy that made a camera sensor out of a memory chip with a clear aperture, I think it was EPROM. As the exposure proceeds, the cells fall back to their reset state one by one)

* dye display: cut strips of metal gaze, attach them vertically and horizontally on each side of a piece of cardboard, cover with a sheet of paper on one side, put the whole assembly between plexiglass sheets or insert into a transparent envelop and drench with
a solution of a metal salt and pH indicator dye (e.g. Bromthymole blue). As you force current through a crossed pair of stips, electrolysis locally creates alkaline and acidic regions on each side of the cardboard that are visualized by the dye. Now that's what I call e-ink.

Excellent thread, by the way!

Nah

Wed Feb 02 2011, 03:49PM

Registered Member #3567 Joined: Mon Jan 03 2011, 10:49PM
Location: USA, 1960s
Posts: 260

Breaking into a top secret government lab, stealing their 1 MWatt laser and......

Creating a laser fruit cutter.

On topic....

Winshield wipers that work like columns going back and forth, getting to those spot that never get wiped.

Using mercury rectifiers to create a nightlight.

hboy007

Tue Feb 15 2011, 09:39PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374

* build an influence machine out of clear CD protective discs
* put the influence machine under high vacuum to create x-rays just like the sticky tape roller you saw the other day.
* etch the back metallization of piezoelectric transducers into segments, group them together in 3 phases and see if you can drive it to oscillate in a rotating wave pattern. Press a friction ring onto the assembly and enjoy your homebrew ultrasonic motor.

hboy007

Sun Jul 17 2011, 03:52PM

Registered Member #1667 Joined: Sat Aug 30 2008, 09:57PM
Location:
Posts: 374

* I just read something about EUV lithography and that gave me an idea for a serious PCB resist writer:

there are some cheap and tiny DLP projectors out there now, like the SP-H03 and ACER-C20 and also some 3W 395nm LED modules

So why not exchange the LED inside the projector (have all colors run at near-uv or leave the green emitter to project alignment patterns), replace the lens by a 1:1 relay lens or an off-the-shelf macro lens (2:1 or 5:1 will still be usable projection ratios) and put the PCB on a xy coordinate table.

As with stepped exposure of reticles onto the wafer, one could stitch the exposure pattern. Since the original lens is being removed and the DLP chip size only limits the speed of the exposure in total, the DLP resolution is irrelevant and any DLP projector will do.

* 3d negative printer: using a standard inkjet printer loaded with distilled water in a fridge, a "page" representing one layer of water droplets, a casting mold made of ice is formed. Once finished, it can be filled with a 2K resin (epoxy, PU, silicone...) that hopefully hardens a little below 0Â°C

If this cannot be done, you can still use food dyes to print 3d sculptures within popsicles :D - good luck finding clean and unfilled ink cartridges...

@Conundrum: I bet you consider trashing the laser scanner approach now

Edit: removed some typos and introduced new ones :(

Conundrum

Sun Jul 17 2011, 06:34PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062

I have this exact idea *2 with the freezer plate written on my wall, and STILL haven't got around to building the stupid thing.

Grrrr...

I would try this but both my DLP's have been rendered unconscious by power supply fryage.

If anyone has a use for the modules, PM me. I tried to reverse engineer the pinout but its a total horse when the PSU won't even twitch.

I did come up with a nice idea, 8 channel programmable power supply with PC WiFi interface.
Generates any voltage from -30 to +30V on any pin configuration, can "learn" unknown connectors by determining connection configuration with an external Gnd clamp, and also calculates likely voltages by measuring under low current to see where the foldover point begins.

As far as stupid ideas go, UV reactive contact lenses with a UV LED mounted on each side of a pair of glasses at an oblique angle so the user's eyes glow like something unearthly.

(Disclaimer:- DO NOT use anything shorter than 400nm or focussed if you value your eyesight!)

-A

Chip Fixes

Sun Jul 17 2011, 07:17PM

Registered Member #3781 Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701

big5824 wrote ...

Zb wrote ...

Heated windshield wipers. I'm this close to just taping some resistance wire on the damn things.

Thats a pretty good idea :D Would work even better if you could add another setting to the car that would slowly move the wipers across the screen to defrost it in one swoop

Ah a great idea indeed, I know it's bad to use metal on a windshield so maybe you could find a material that can get pretty warm without melting, then make a sleeve out of it that can slide onto the plastic part of the windshield wiper, like you change the rubber blade with a heat resistant one that can defrost the windshield.

A simple solution to make the wipers move slowly is putting a pot in line with the speed adjuster control thingy

EDIT: you could make a pretty simple wiper out of the conductive tape Conundrum suggested

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