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Re: SMD's
Keith
--- In Electronics_101@..., "Kenneth Smith"
<kensmith52@y...> wrote: What method of soldering do you use. I have done some research on A tip given to me for SMD rework which I use for very fine pitch TQFPs: smother the legs with solder then use de-solder braid to remove the excess. It leaves the solder connecting the legs to the board but removes all the short circuits. Keith. |
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Re: I almost didn't come home today - SAFETY!
Rod Baxter
开云体育Unfortunately even experienced electricians can get caught. About 15 years ago I was installing a mainframe computer which had a large Frequency converter to run it, about 50 KVA. ?The inspector who came to check on the electricians work checked the output of the converter and said it wasn’t working. I grabbed his hand as he went to touch it and stopped him electrocuting himself. What he had done was use his phase rotation meter to check the output and it did not work at 400Hz which was the output of the converter. I used my meter and showed him it was working, he went a bit pale and left! I am not a licensed electrician but I suspect I know more about electricity (and the regulations) than some electricians unfortunately. ? Anyone can make a mistake I guess, the trick is to make sure they are not fatal.. ? Sorry to be OT here, but I get upset at some of the stupid licensing regulations we have in this country. ? Rod ? -----Original Message-----
From: peter tremewen [mailto:Ptremewe@...] Sent: Sunday, 18 April 2004 4:45 PM To: Electronics_101@... Subject: Re: [Electronics_101] I almost didn't come home today - SAFETY! ? This is one of those scary stories that convinces governments to make sure that only licensed electricians should do electrical work. Even scarier is the possibility that the person who did the install probably WAS licensed. ? ??? ??? The Sinister Dragon ? From: ghidera2000
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Re: I almost didn't come home today - SAFETY!
Logic Research Electronics
开云体育Hi,
?
I am registered as an electrician (for almost 20
years) and although there are some cowboys out there, such bad workmanship is
not tolerated.
Not earthing any fitting is beyond a joke and can
result in loss of practicing license and a huge fine which would pretty much
ruin a person.
?
Get yourself checked out by a doctor as the
effects of a shock (on your heart) can?appear several days after the
shock.
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Re: I almost didn't come home today - SAFETY!
开云体育This is one of those scary stories that convinces
governments to make sure that only licensed electricians should do electrical
work. Even scarier is the possibility that the person who did the install
probably WAS licensed.
?
??? ??? The Sinister
Dragon
?
From: ghidera2000
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I almost didn't come home today - SAFETY!
This may be semi OT as it is electrical, not electronic.
I work as a stationary engineer for a municiple government. Part of our duties is minor electrical work - things like changing lamp ballasts, fixing broken outlets, changing electric motors etc. Anyway, I got a work order this morning saying that one corner of a florescent fixture was pulling away from the ceiling in a preschool room.I looked and one corner was sagging down about 1/4". I grabbed a ladder and went up to see what was happening. I touched the fixture and *ZAP*. Not a big jolt, but my fingers were a bit numb for 15 minutes or so. Needless to say, the power went off REAL fast after that. I took the lens off, the tubes out, and removed the ballast cover. First thing I noticed was the lack of a ground wire... Not a loose ground - it was completely missing! Next thing I noticed was that the knockout was bare. No bushing was installed at all! I grabbed the hot and sure enough, the sheet metal had cut through the insulation and charged the entire fixture to 120 volts - WITH NO GROUND. Thankfully, I was using a wooden ladder and had touched a painted portion of the light. It doesn't end there either. I took the fixture completely off the ceiling and in the process discovered that the installer had simply used metal screws directly into acoustic ceiling tiles! No joists above, no toggle bolts, not even stupid drywall plugs. What boggled my mind was that this fixture had been there for at least 12 years (as long as I've worked there). And the room above this is a gymnasium. When people run around, the ceiling shakes so much that aluminium angle was screwed onto the fixtures to keep the lenses from falling out. Still not finished! The junction box was 6" to the side of the knockout they used so the wires were sandwiched between the ceiling and the fixture then had to do a 90 through the (unbushed) knockout. The junction box itself was not attached to anything. It just had a piece of wood screwed to it so it wouldn't fall through the hole in the ceiling tile. As you probably guessed, yes, most of the wires are NOT in conduit, they were just run along joists with staples. There was one wire in conduit, which simply ended and the wire then did a 100 degree turn and got fed into the junction box. There were three sets of wires led into the box - each with a ground. All of them were neatly wire nutted together... NOT attached to the junction box OR the fixture. I looked around the room, there are 12 other fixtures... Needless to say, the big boss, the medium boss, the little boss, and everyone in between has heard about it. That room is a death waiting to happen. Moral of the story - NEVER "make do" with wiring. If you're going to use dangerous voltages in your projects, DO IT RIGHT or scrap the project. The person you kill may not be yourself. |
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Re: SMD's(Thanks All)
Roy J. Tellason
On Saturday 17 April 2004 07:06 pm, Phil wrote:
--- In Electronics_101@..., "Kenneth Smith"Then I have at least a couple of years on you. And as far as this SMD stuff is concerned? I just ain't gonna go there... I've seen a division lately in how I relate to this stuff. On the one hand there's stuff for fun, and with that I can stick with technology that's a decade or three out of date, I've scrapped enough stuff that I really don't think that I'm going to run out of most of it anytime soon. And on the other hand is stuff that I just *use*, and will buy it when I need to. I see SMD as a convenience to manufacturing, no more. |
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Re: Looking for component storage drawers from Tech America, or similar
Long time ago I worked for a company that carries some very cheap soft
poly plastic lidded cassette tape cases. I put parts in them and put them in cassette wall mount racks. Like this: A pair of flush cutters will snip the posts off if needed. I write on the edges of the boxes with a grease pen. Alien Steve --- In Electronics_101@..., Stefan Trethan <stefan_trethan@g...> wrote: ;-) that seems to happen all around the world...myself for neverhelp i guess. |
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Re: Triac instead of relay ?
--- In Electronics_101@..., "manifold" <manifold_1@y...>
wrote: --- In Electronics_101@..., Stefan TrethanSince the turn on point is delayed: The voltage and current in a resistive load are in phase. However, if you look at the voltage coming into the whole circuit, the current phase is delayed because of the delay between zero voltage crossing and when the triac turns on and causes the start of current flow. Alien Steve |
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Re: SMD's(Thanks All)
--- In Electronics_101@..., "Kenneth Smith"
<kensmith52@y...> wrote: Thanks Guys for the information.wanted to get to a smaller board design.If you are older than me, its not by much... Graduated HS in 71. Phil |
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Re: I almost didn't come home today - SAFETY!
开云体育In a message dated 4/17/2004 9:43:34 PM Central Standard Time, ghidera2000@... writes:
Moral of the story - NEVER "make do" with wiring. If you're going to ?
Did I hear "Wired in accordance with EEOC rules!" ? ? ? |
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Re: Triac instead of relay ?
开云体育In a message dated 4/17/2004 8:53:47 PM Central Standard Time, csakima@... writes:
I thought only capacitive/inductive elements creates angle shifts .......?? Curtis is correct.? |
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Re: Looking for component storage drawers from Tech America, or similar
Stefan Trethan
check ebay too....
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If you're referring to the picture on the right, those kinds of parts bins |
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Re: Looking for component storage drawers from Tech America, or similar
Roy J. Tellason
On Saturday 17 April 2004 02:35 pm, John Johnson wrote:
I bought these component organizers at a RadioShack.com store that wasIf you're referring to the picture on the right, those kinds of parts bins are often seen in both hardware stores and home centers, holding all sorts of stuff. Odds are that those places end up getting them from whoever is supplying them with the assortment of parts stocked in them, so you'll probably have to pursue it that way, unless you're lucky enough to find a hardware store that's going out of business too. But this should at least give you a place to start looking. Auto parts stores sometimes use something similar for things like light bulbs, come to think of it. |
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Re: SMD's
Stefan Trethan
I?ve only done one project so far with SMD it was aif the pin spacing is wide enough this works perfectly well, without needing luck. I use this metod often with the mixed boards, with 1206 and 0805 components and wide spaced chips. I use colophony resin as a flux, solved in laquer thinner. it doesn't attack the copper and actually acts as a protective laquer. i usually don't clean it off. It is ok for the standard circuits, maybe for very high impedance things or very high frequency it could be bad. After all in a big number of solder wires this flux is used as the flux core so i think it is not bad for the copper or components. If you have a lot of parts or too small spacing it is very convenient to use a oven. you apply the paste, ideally with a pneumatic dispenser that dispenses a precise amount each time, then put all parts on with a vacuum pipette and put it in the oven. the paste reflows, the parts align, ready. The result looks just like any professional board you look at. Bad thing is i have no oven and i have no pneumatic dispenser, both on the "to do" list. ST |
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Re: SMD's
--- Phil <phil1960us@...> wrote:
I bought a decent temp controlled station (90-ish $$I got a super thin tip for my iron but found that theI?ve only done one project so far with SMD it was a kit for a microphone amplifier. I got a new thin soldertip for my Weller wtcp (about 1 mm thick and some thin solder. And away I went, more or less ordinary soldering technique. Maybe I was just lucky, but I didnt have any problems at all. Next time I will add a magnifier to the setup. Henning __________________________________ Do you Yahoo!? Yahoo! Photos: High-quality 4x6 digital prints for 25? |
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Re: Looking for component storage drawers from Tech America, or similar
Stefan Trethan
;-) that seems to happen all around the world...
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I hate the chaos of different storage systems i have and i hate myself for never buying enough of one kind.... I know where you can get similar drawers in germany but that doesn't help i guess. is that really such a tight fit with that car of yours? ST On Sat, 17 Apr 2004 14:35:47 -0400, John Johnson <johnatl@...> wrote:
I bought these component organizers at a RadioShack.com store that was |
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Re: SMD's(Thanks All)
Kenneth Smith
Thanks Guys for the information.
The Oven method was the one that was in question. I have been in Electronics since 1967 thru government schools of soldering and was a Field Radio Mechanic. I am currently repairing Satellite Equipment and building V.35, Rs422 cables for companies all over the world. I also design Electronic equipment and a programmer in 5 langauges. But still there is something new comes up that gets my attention and I try to figure it out by the internet. Most of the time it works but you guys seem to latch right on to it. Maybe I am just getting too old for this. The reason for this is I use a lot of Pic's and wanted to get to a smaller board design. Thanks Again Ken Smith --- In Electronics_101@..., Stefan Trethan <stefan_trethan@g...> wrote: method a) soldering iron - works only to a certain spacing.and flux.
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Looking for component storage drawers from Tech America, or similar
John Johnson
I bought these component organizers at a RadioShack.com store that was going out of business. They were sold by another division of Tandy called Tech America. Tech America also went out of business. Their website is gone too. RadioShack doesn't have any, and can't get any. Does anyone know where I might find more of these, or similar organizers. I've Googled until I'm blue in the face, but haven't found anything.
Thanks in Advance! Regards, JJ |
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Re: SMD's
When I finally worked up to courage (yes, its intimidating) to try
SMDs, I read everything that google could find. There are a bunch of techniques but you dont need to invest in expensive equipment. I bought a decent temp controlled station (90-ish $$ but you can find good enough for even 1/2 that) and just tried. I made a practice board with a bunch of pads (1206s, 805s, sot23, and several sizes of SOICs). I bought a grab bag of parts and a couple of the cheapest SOICs I could find (lots on ebay but mouser/digikey/... all have them). All in I spent less than $10 for the test parts and have lots left over. I got a super thin tip for my iron but found that the size that came with it works just fine (is small but not THAT small). In hindsight, I should have gone straight to a project. I use the "tack a corner" approach and liberal flux. Put a small dab of solder on a corner pad. Then holding the iron on side of the pad to keep the solder melted I slide the part into place using foreceps. Once in place I take the iron away and the part sticks after a second. If its not right, I put the iron back and tweak the position. Then I put a little dab of solder on the iron and touch it to each lead - it flows in about 1 second. I can usually get 2-3 leads per dab of solder. I can do SOICs in about a minute. 1206s, 805s in 20 seconds or so. SOT23s are the trickiest for me but they are pretty quick too. Sometimes you will get bridges but solder wick does the trick. I'm hooked and try to use SMDs where ever I can. Phil |
Steven AE7HD
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