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That MacGyver moment

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Dr. Slack

Thu Jun 14 2007, 12:07PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

You know how it is, you've only got 17 minutes to save the Earth, and all the shops are shut, so you take a wander into your shack/garage/den and wait for inspiration to strike.

It was 8pm one evening when my wife told me that the birds were eating the grass seed she'd put down a few days earlier, now she tells me! Solutions?

Bird netting? No, the shops are shut.
Closely spaced strings? I do happen to have 2.5 miles of steel wire (4 core command wire from an anti-tank missile) on a reel, but it's a big area, that's a lot of pegs and stringing, and I'm sure there's something better I can do with such a resource, so no!
Bird scarer? Propane/air, spark ignition? What about the neighbours, what about my sleep?
Scarecrow? A suit stuffed with paper on broomhandle? You want this to work, right, to actually be effective?

I disappeared into the garage. TDU's Tesla coil car protection system bobbed up into my head.

6rpm mains gearbox/motor, rescued 25 years ago from a skip, mount onto a scrap of PCB. Drill two holes in the pulley. Hot-melt and self-tap (never throw a toy away without removing the self-taps) the PCB across the end of a 100mm PVC TC secondary former offcut. 3 alli strips connect the tube, motor shaft down, to an inverted empty 2.5l paint container as a rain-shield, strips extended above and drilled to provide hanging eyes. Add a mains cable and connector (never throw an appliance away without rescuing these) inside the tin so any water runs away from, not towards, the connector. Run a rope from one tree, over the shed, to tie on the fence, to provide a suspension point over the grass-to-be. Use string to suspend the rain-proofed motor above the ground. Two 8ft bamboo canes, make into a single 15ft long stick with 2 tough elastic bands (the seals saved from the waterproof cases on beach cameras, dismantled for the PFCs and AAs). Cut and bend an old bicycle spoke as a cradle for the canes, to hook into the holes in the pulley, to hang horizontally below the motor. Finally balance the canes by winding on a few turns of copper wire. Adjust the height by slackening the rope so the canes are a few inches off the ground. Switch on.

Because I knew it was going to be such a bonkers thing to do, I timed myself. It took 53 minutes and cusses beyond number from first pondering the problem to first powering the bird basher. It got the expected response from my wife. "You what, you built WHAT?" I reminded her that it was her fault for marrying an engineer.

Birds don't get bashed, they just don't go there. I wonder how long evolution would take to produce pigeons that jump every few seconds when feeding? The grass is now sprouting. Visitors to the house are bemused. A manual bird control device is forming in my mind, a spud gun the size of a BB gun, that uses sultanas for (bio-degradable) ammo.

What improbable gizmos have you designed and built against the clock as overkill or unusual solutions to problems, using your copious supply of skill and scavenged parts, to the astonishment of all?

Tesla_Cubed

Thu Jun 14 2007, 01:55PM

Registered Member #594 Joined: Tue Mar 20 2007, 04:02PM
Location: Joplin Mo USA
Posts: 6

A number of years ago. After I had just learned to drive a friend of mine ask where were on the map I looked down and said " I cant look right now or I drive the car into a storm drain or something" fowled by the crunch of my ford tempo going into guess what ......

..... A storm drain pipe.

[ do we have a irony smiley]

Well after the tow truck pulled us out my intercoller was smashed along with the front bumper. I could limp the car home but It would ruin the transmition. I found a bic pen took out the guts and used the case to bypass the now smashed intercoller. Her frends and the towing company have called me MacGyver ever since.

89 ford tempo ~ 1500$
bic pen ~0.38$
tow truck ~56$
getting to be MacGyver "Priceless"

Simon

Sat Jun 16 2007, 02:06AM

Registered Member #32 Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549

Nice story, Tesla Cubed.

MacGyver is an inspiration for life.

All I can think of now is my sound system. A few years back, I lay on my bed to listen to some music and found my CD player had died. That sucked. So I was lying there thinking of how I'd have to buy a new one (I was a school kid with no job) when I realised I had no need to buy one.

An hour or so of scrounging in my electronics stuff later I had:
*A CD burner - was being thrown out by a computer "repair" shop some time back. It still played CDs fine.
*A PC PSU - from a 486 that a different computer shop was throwing out another time.
*A pair of speakers - from an okay sound system that had died - speakers intact.
*An amp - one I had lying around.

With a little soldering iron work, I had a new sound system. I still use it, though I've replaced the amp for a better one from a shop (I have money, now).

For that extra MG touch, I have a paperclip sitting on my system, to open the CD burner tray when the power is off.

ragnar

Sat Jun 16 2007, 08:16AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Hehe, I've had the exact same MacGyver moment as you -- a dead Creative burner which couldn't write but could still read. The noisy AT PSU always annoyed me, though. ^,^

...

Sat Jun 16 2007, 08:38AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Hmm, I had to make my hotplate because I had just become the proud owner of a few KW worth of 808nm pump diodes, in unmounted bar form. So my problem was-How is one supposed to take over the world when their laser diodes aren't properly soldered to a copper mount?
The answer was simple-grab some typeK thermocouple wire, thermal glue, and aluminum plate, and bake at 150C for 30 minutes. (ie, hook the heating elements to a really whiney ATX PSU) Worked great, I have mounted all of the 50w bars and a few of the 25w ones (sold most of them off unmounted, killed a few learning how to mount them

) and it is still going strong. I am not quite ready to take over the world yet, I am waiting for a few pieces of copper to come in, and then I can start work on my fddpss laser, which is all goes well should give 5w+ of 532nm green

I also have plans to use a mid sized yag rod designed for flashlamp pulsing (so it has enough Nd ions to store a solid fraction of a joule of energy in it) and a self contained a-o q-switch so a 10w q-switched yag. If I can that working I should be able to cut just about anything, (in theory, when focused I should get air ionization, so I can use my floating plasma ball to cut things like glass/ceramic that wouldn't absorb the 1064nm)
Right after I get the gps tracking system working, finish my RGB laser, package up my ssy-1's...

Nik

Sat Jun 16 2007, 09:49PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I managed to fix a broken clutch cable with a fule line clamp.

The broken bit

My MacGyver moment

ragnar

Sun Jun 17 2007, 09:11AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

I'm thinking of what could be an interesting MacGyver moment at work -- my aim being to build a class-E SSTC COMPLETELY from parts found ONLY at Jaycar (an Australian electronics store) see http://www.jaycar.com.au/

At the moment, I'm faced with several problems:

Jaycar don't sell any really useful MOSFETs apart from some expensive 160V 7A thing,
nor do they sell any gate-drivers,
nor do they sell any pipe which I could use as a former.

So I guess I'm going to have to use a cardboard toilet roll as the former, I think I can use a ULN2003 chip as a gatedriver (don't know if it will work to 4MHz, we'll have to see -- may have to use resonance and a GDT to get the current needed)... and 160V isn't actually too bad, I can use it on 24V or 36V.

Because I don't want to mess around with too many magnetics and matching networks, I'll just put the primary in series with the drain supply, heheh.

I think that covers everything. ^_^

thedatastream

Sun Jun 17 2007, 11:26AM

Registered Member #505 Joined: Sun Nov 19 2006, 06:42PM
Location: Yorkshire!
Posts: 329

I've often thought about building a tesla coild from materials ONLY found at Ikea. Dissasembly of transformers would yield the necessary wire and you could take it from there!

Simon

Mon Jun 18 2007, 04:07AM

Registered Member #32 Joined: Sat Feb 04 2006, 08:58AM
Location: Australia
Posts: 549

BlackPlasma wrote ...

Hehe, I've had the exact same MacGyver moment as you -- a dead Creative burner which couldn't write but could still read. The noisy AT PSU always annoyed me, though. ^,^

I either use headphones or turn the speakers up.

There's a little 50Hz hum, too, which could possibly be due to the abuse of the PSU.

Nik

Sun Jul 01 2007, 10:58PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

Using a 1/4-20 bolt, nut, washer, 2 10-1 screws and a block of 2x4 I made my telescope tripod into a camera tripod.

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