Products > Test Equipment
Test Equipment Anonymous (TEA) group therapy thread
tggzzz:
--- Quote from: bd139 on May 15, 2018, 10:04:21 am ---
--- Quote from: tggzzz on May 15, 2018, 09:48:54 am ---Ob porn: the front panel showing rise and fall time controls, and one interior shot showing old-school wiring looks and, if you look closely on the left, 863pF, 908pF and 9.85nF capacitors.
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That's a thing of beauty! :-+
Another xfce user I see as well :D
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Yup. I chose that because
* there's nothing kewl about it; it just works without me having to think about it
* works nicely on a 2012 1.6GHz/1GB Atom netbook - and wonderfully on anything newer/biggerand I standardised on it before Linus publicly stated he had :)
Now that Unity has bitten the dust, maybe I'll try Mate/Cinnamon - but quite frankly I can't see any benefit to reeducating myself.
bd139:
Don’t bother. It’s like fighting a crocodile. Xfce is the safe house in the woods. Desktop’s job is to get out of the way and let the applications do their thing, not be clever or fancy.
Just blew some cash on some storage for parts in hobbycraft. Decided to organise and clear out all the shit that is in my cupboards. It can fund some new toys then :D
mnementh:
--- Quote from: Cubdriver on May 15, 2018, 07:55:49 am ---
--- Quote from: bitseeker on May 15, 2018, 04:52:12 am ---
--- Quote from: Cubdriver on May 11, 2018, 02:33:10 am ---
--- Quote from: BillB on May 10, 2018, 06:04:27 pm ---
--- Quote from: rhb on May 10, 2018, 05:59:07 pm ---...I got rid of my adult supervision quite a while ago, so I have no one to protect me now...
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Aha! Now I understand how such a purchase is possible.
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Yay for lack of adult supervision!!
Hmmm... On second though, perhaps some adult supervision might be a good idea...
Nahhh, screw it. That ship has sailed. Off to the bay of evil!!
-Pat
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They're congregating...or perhaps colluding. Did you recently schlepp some of the units I see there?
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Indeed I did. You obviously recognize the pile just to the left of center as my recent score.
-Pat
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You can just "misplace" that Makita chopsaw in my direction any time you want to stop stubbing your toes on it; my crusty old DeWalt (Boutique branded Black & Decker pecker wrecker) is about on its last legs. I expect the gearbox to actually grenade pretty much every time I pull the trigger now...
mnem
Of course, before i can use it, I'll need to rebuild the stinger on my MIG... oh the heartbreak. :-DD
mnementh:
--- Quote from: tggzzz on May 15, 2018, 07:46:54 am ---
--- Quote from: bitseeker on May 15, 2018, 04:52:12 am ---They're congregating...or perhaps colluding.
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Excellent collective noun: "a collusion of test equipment"
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When I was young, and my electronics bits and pieces were scattered from hell to breakfast all over the house... my mother used to tell me they were plotting to overthrow her tyranny. She would point out the test gear I happened to be using at the time (usually assembled in stacks in a circular fashion on the floor behind and table in front of me) which was always old and crunky and scarred as it was all third or fourth-hand, and say they were holding court, with me the accused in the middle.
*Sigh*
Remember when we just did it for the fun of learning?!?
mnem
*Miss you mom*
Cerebus:
--- Quote from: bd139 on May 15, 2018, 10:30:19 am ---
--- Quote from: Cerebus on May 15, 2018, 10:20:17 am ---
I'll have to try and find some schematics for that. I had cause recently to design (read lash up) a pulse generator with variable symmetric rise and fall times; pretty easy really, a couple of adjustable constant current sources and a diff. pair as a current switch. What wasn't obvious was how to make the rise and fall times independently adjustable other than doubling up the former circuit and adding some switching diodes. I'll have to look and see if Tek had a cleaner solution.
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Damped miller integrator? I built one of them a few years ago to get adjustable rise time. If you stuff a small cap across B-C junction with a (trimmer in my case) resistor in series with it. Doesn't affect bias yet slows the transistor down.
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No. It's quicker to draw in LTSpice (and even simulate) than it would be to give a purely word description. Please excuse the crudeness of the model, I didn't have time to paint bias it properly or create a decent output clamp. In a fully fledged version you'd use something a bit better than a pair of back to back diodes to guarantee something like a flat top.
There's two differential pairs acting as current switches. The top one switches the charging current, the bottom discharging. You set the current of the constant current sources Irise and Ifall to control the rise and fall times.
The output:
That's the Tektronix version in rough outline. The version I used before didn't have the top differential pair, just a current source, and the current source off the tail of the bottom pair was twice the value of the top current (i.e. Ibottom = -2 * Itop). Switch on and you draw (Itop - 2*Itop) out of the capacitor, off and just the top current source supplies Itop.
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