Scientists working for the Anglian Regional Space Effort here in Cambridge, have developed a new waveform: the sharktooth (see oscillogram above).
Experts are already hailing this as a new scientific breakthrough, more important than big bang theory, more revolutionary than the microchip revolution, proving once and for all that time travel is no longer a thing of the past.
(Chuckle) I once designed a system that drew vector graphics. I hooked it up to my 465B scope and made it look like I had a ringing square wave with a slightly negative risetime. It looked quite convincing unless one noticed that the scope was in X-Y mode...
Not to change the subject (Heaven forbid!) but you can get some cool effects connecting the vertical input of an analog scope to a photodetector, like a pmt, and aiming it at the screen. It can be made to "trace" objects near the screen, like your fingers or whatever, and it falls off the edge of objects as the sweep passes. It amused me, anyhow, when I was about 11 years old.
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| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
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I love to cook with wine. Sometimes I even put it in the food.
You owned an oscilloscope at 11! I'm well impressed.
I owned two morse code keys that I bought from Wireless World for 7/6. They had straps that, a local airline pilot friend-of-the-family told me, were thigh straps. (The radio was worn on the back, apparently).
I did that too :) Also made a "television" by connecting a (555) sawtooth circuit to Y and modulating the Z input. (With the video output from a home computer IIRC). The synchronization circuit consisted of manually tweaking the 555 timing resistor to try to match the video. If you got close enough it would "lock in" somehow.
Back in the 1940's in WW2, dad worked for E.K.Cole, who made manpack radios for the British Army. They had developed a new version, and had the sign-off meeting with a bunch of senior guys from the MOD and the Army.
The aerial for the set was a simple trailing wire, and this upset the Army/MOD representatives, due to the perceived possibility of it snagging on something in the field. This caused an impasse for a while.
It happened that there was some renovation work being done in the building, and someone had a bright idea - they went to the builders and got some twine (string), attached this to the end of the wire aerial, attached a tab to it and got the squaddie who was "modelling" the radio to tuck this in his sock.
Great! This satisfied the MOD/Army guys (never mind the real practicality), so they signed off on the design. This was written into the specification as "Twine, Builders". Everyone went away, happy as Larry.
Cut to a couple of months later, production in full swing. Except.... the builders had long since gone, and they couldn't identify exactly what twine had been used! That completely stalled shipments, as it was in The Military Specification. The company had to trace the builders (not that easy, it was one of those "someone knew someone" slightly shady jobs), then find out where they had got the twine from and buy some before they could ship the radios to the army.
Heh heh, this sounds like a load of old shark's teeth to me. Now if you said that you built a nuclear reactor in you backyard, that I could believe -:)
I admit that the scope was a Heathkit, OM-1 as I recall. I used to buy the kits, build them, and sell them for what I paid, then buy another one. It never ocurred to me to try to make a profit.
I did, about that time, build a number of strange oscilloscope-y things out of parts. My favorite CRT was a 4FP7, a square-faced electrostatic deflection tube with pda and the cool long-persistance phosphor, a mil surplus radar indicator that cost just a few dollars. I recently bought a couple more from Fair Radio Sales (same place, probably the same lot of tubes, that I bought as a kid!) for nostalgia, and they're still very cool, but $25 apiece now. I have one on the bookshelf right above me, and it glows happily when I turn out the light.
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Sorry to disappoint you, but not even the slightest begining of a shark tooth :-)
I must admit that I cheated a bit and the time base was an adapted one from, a Telequipment (D65 IIRC), probably because of the triggering circuit, but I clearly remember already knowing how to obtain a linear sawtooth (no, not shark tooth). The CRT was a DG7-32, the only one I could buy. All the rest, i.e. V/H amplifiers, input attenuator, blanking were home designed. The supply transformer was custom made for a very modest price (some nice people took my project into sympathy). It was even dual traces and the chassis was home made from glued aluminium small U profiles my father used to frame large mirrors.
The same person that had the xformer wound for me then lent me a scope for about a month so that I could debug it. I remember having had really bad time with spurious oscillations. But with perseverence (and probably a load of luck) it finally got to work. At least well enough for my needs of the moment.
I used it for 3 years before buying my first commercial one (Hameg HM412).
I think I still have it in my parents' house basement. When I'll return there, I'll try to remember to make a pic.
The main thing I gained with this experience was to not being afraid of seemingly unreachable targets. Serves me a lot today.
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