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I think I am starting to really lose it.... Answered

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I was building the "Evasive Beeping Thing" from Make. A search through all of my "parts" finally got me resistors and caps of approximately the correct values I wanted *even though they are not specified in the article :-( ". After nearly a fortnight, I finally was ready to test it. hooked up a nine volt battery, and.....nothing. Fearing the worse, I touched the 555 IC...and it was hot as blazes.
2 days of inspecting the circuit and trying to make sure no shorts were occurring, I finally gave up and unsoldered the whole thing.
I then through together a quick 555 timer circuit using an ic socket, in order to test if I had destroyed my IC. That didn't work at first (but just in case, I tried a 555 I knew was good, and that did work). Just before throwing out the assumed defunct 555, I looked at it under a brighter light (and low and behold, on the IC was written in very small worn type: 741. It was an op-amp ! I could have screamed....*sigh*. Oh well, at least I got a tester out of the deal LOL
*sigh*

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Plasmana (author)2008-10-14

Ouch! That is the problem, most of the IC's are so alike! That reminds me of the recent electronic accident I had, I blew up the PCB copper tracking...

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Goodhart (author)Plasmana2008-10-14

I don't mind them being alike (makes using sockets easier), but the type written on it (part ID) was so very tiny and light.....I had troubles determining just what it was. BTW: how did you do that to the copper tracking?

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Plasmana (author)Goodhart2008-10-15

Yeah, that is same for me... The copper tracking blew up from too much current, I accidently put the solder tracking on the wrong copper track (as you can see in the picture) where it carries very little current. Oh, and that is my flyback transformer driver.

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Goodhart (author)Plasmana2008-10-15

My 555's are printed on pretty plainly, but that 741 was lightly etched, and if there had been any printing on it, it had worn off in transit.

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Plasmana (author)Goodhart2008-10-15

Oh, that makes sense then.

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Goodhart (author)Plasmana2008-10-15

Yeah, with a CFL light right up against it, I finally did see what was printed on the 741 grrrr. :-)

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Plasmana (author)Goodhart2008-10-15

Here are more pictures...

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guyfrom7up (author)2008-10-06

haha i don't like 555s, too many external parts and it's a hassle...

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Plasmana (author)guyfrom7up2008-10-14

What do you use other than the 555 timers?

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Goodhart (author)guyfrom7up2008-10-07

what are you thoughts about using a 741 Op Amp instead LOL

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Goodhart (author)2008-10-13

I finally got the 555 tester up and running..... now to start to work on the other project :-)

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Lithium Rain (author)2008-10-07

Gah! Goodhart! You keep scaring me!

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Goodhart (author)Lithium Rain2008-10-07

Sorry, in this case, losing it means I nearly felt like trashing my own workbench :-)

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Lithium Rain (author)Goodhart2008-10-07

Lol...one day I'll learn not to assume... :D

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gimmelotsarobots (author)2008-10-07

Oh well, it doesn't hurt for something like that to happen every now and again. It makes life interesting. Say, could you send me that circuit? : )

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I could try to post the schematic if that is what you mean.

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BTW: The pictured device I use to "test" 555's, that isn't the "Evasive Beeping Thing"

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I won't know how to create the schematic for the EBT until I get one working :-) do you still want the schematic for the "testor" pictured ?

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Umm.. no I can make one of those. What is it? An oscillator or a on-time timer (push button outputs for certain period).

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. AKA one-shot or monostable

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ONE-SHOT! Thats the term I was looking for.

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Yes the EBT is a monostable setup HOWEVER, it has an additional timer circuit involved to cause the cycle to repeat at specific periods of time. This involves a few transistors, and I do think I have figured out that part of it too, Still, I don't yet have one built. If you meant my tester, it is actually setup as an astable multivibrator, whose output is to a speaker and oscillates at an adjustable frequency (for those that can't here in the higher range ;-)

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I think I built one of those.

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I have to remember this when I have a little more time.... sorry for the delay...

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NachoMahma (author)2008-10-06

. Sure am glad I've never done anything that bone-headed. ;)
. You still gonna try to build the EBT?

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Goodhart (author)NachoMahma2008-10-09

I remember the time I subbed a 3.3 k resistor for the required 330 k in a circuit, ....one word.... smokin'

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Goodhart (author)NachoMahma2008-10-07

Yes, I am. I constructed a little "555 tester" to make sure I don't fry one and frustrate myself again, in another way. (now I need to build a 741 tester so I know if I killed that chip or not ;-) Part of the problem is my up close and personal eyesight is slowly fading....*sigh*

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NachoMahma (author)Goodhart2008-10-07

. Welcome to the club! I've starting keeping magnifying lenses and reading glasses handy. Been a few times when I had to grab one of the kids next door and say "Here! What does that say?"

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Goodhart (author)NachoMahma2008-10-07

I have one of those BIG lighted ones on an adjustable arm right there at the desk, but I have to crawl under the desk to plug it in (last time I knelt on the floor, I bruised my knees pretty badly). But I guess I have to just get some padding and do it :-)

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NachoMahma (author)Goodhart2008-10-08

. I know they weren't around when you were a young lad, but there is this new invention that may help you out. It's called an extension cord. Google it.

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Goodhart (author)NachoMahma2008-10-08

pssst I still have to get down on my knees to get under the desk to plug it into the wall.....unless your new fangled extension cord can seek out sockets and plug itself in ;-)

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NachoMahma (author)Goodhart2008-10-08
. Two other great new-fangled contraptions: the cube tap and the power strip. heehee
. To be uncharacteristically* serious, you really need to protect those knees. Extension cords (you only have to plug it in once, then run the business end somewhere handy), &c are cheap compared to new knees.
.
  • Kudos to who(m?)ever invented spellcheck.

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Lithium Rain (author)NachoMahma2008-10-08

Being old must really stink. >:D

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NachoMahma (author)Lithium Rain2008-10-08

. Much better than the alternative. ;)

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NachoMahma (author)Lithium Rain2008-10-08

. Actually, being "older" has many benefits. . How many youngsters have their house and cars paid for? After many years of payments, I do. My income may not be very much since retiring, but my outgo is very little. . I made it through puberty. I'm still a dirty old man, but, without the hormonal flashes, I can hide it better. Wimmen seem to appreciate that. . In spite of the fact that I occasionally bemoan the manners of you whipper-snappers, most younger ppl do treat me with a modicum of respect ... until they find out what a bozo I really am. . I don't have to go to school if I don't want to! . . Sure, it hurts a little when getting out of bed and sometimes my arms aren't long enough for me to read something, but there are other things that help make up for it. . I'm still young enough (on the inside, anyway) that it hurts my feelings a little bit when the neighborhood kids call me Mister Mahma. I don't mind getting older, I just don't like to be reminded of it. :)

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Goodhart (author)NachoMahma2008-10-08

. How many youngsters have their house and cars paid for?

I can only afford to rent :..-.(

But I can relate to your last statement a bit....I don't get upset, just a bit shocked by the Mister or Sir addendum's :-) I forget my age often and don't feel old on the inside anyways. meh LOL

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Lithium Rain (author)NachoMahma2008-10-08

Very true! Mister Mahma! ROFLOL!

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Goodhart (author)NachoMahma2008-10-08

Yes, well I only need to plug in the one light....still, I dread getting down there again on my knees, even with padding (since MY carry along padding is higher up and makes me top heavy...)

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Labot2001 (author)NachoMahma2008-10-07

Sure am glad I've never done anything that bone-headed. ;)

That pulled a laugh out of me ;-)

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NGinuity (author)2008-10-06

I had something similar happen when I built this:
http://blog.makezine.com/archive/2007/01/how_to_make_an_altoids_ti.html

Turns out...the metal case was shorting the ground to the switch on the morse jack. Oh well. If there's no fire, theres no fun!

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Goodhart (author)NGinuity2008-10-07

Well, at least you didn't try to use an OpAmp for a 555 timer in a 555 circuit ;-)

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NGinuity (author)Goodhart2008-10-07

Honest mistake. the IC's look the same, but the "goesinta" and "goesouta" are different :-)

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Goodhart (author)NGinuity2008-10-07

yeah, the 9 volts I was trying to feed the signal-in of the opAmp was probably why is was getting so hot do you think?

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NGinuity (author)Goodhart2008-10-07

I'd be willing to bet that the amount of gain you were feeding it was causing the heat, or, the IC had a dead short.

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