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Basic Electronics » handling microprocessor and static eletricity

November 30, 2012
by keith712
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i just received an ATmega168 which i haven't plugged into a breadboard yet. do i need to ground my hands to plug ICs into a breadboard?

November 30, 2012
by pcbolt
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Hi keith -

Usually it depends on your environment. If you have lots of carpeting in your home, or storm activity etc, it's best to ground your hands before touching any kind of CMOS device. I work in a room with tile floors and never needed to ground my hands. Best rule is if you are worried, it can't hurt (much) to ground your hands on a water pipe or something similar.

November 30, 2012
by keith712
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thanks pcbolt... i don't have rugs but i wear wool socks so maybe i'll take them off and touch my grounded lamp before i reach for the chip

November 30, 2012
by sask55
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I can tell you that dry room air is factor. When it is very cold outside the relative humidity inside often drops. I had a carpetted floor and a rolling office chair in the room with my bench. I the winter on cold days I would get a sizable snap ever time I would move a few feet and touch almost anything. Most of the time I would make use of a wrist band tyoe grounding strap, or touch a grounded surface before reaching for the curciut board. I have at least two USB cables and two or three micros that did not survive a slip up when I heard and felt a unexpected and alarming static discharge. Granted this may be a somewhat local issue, I don't know how many other might get two conecutive week of -40 deg. to deal with.

December 01, 2012
by Ralphxyz
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two conecutive week of -40 deg

Darryl, where do you live??

Ralph

December 01, 2012
by sask55
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Saskatchawan Canada. About as far from any sea coast or open water as you can get in North America,after freeze up. It tends to be cold and dry often for extended periods.

December 01, 2012
by keith712
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-40... two weeks... wow... is that Celsius? it sounds cold enough to get N2 and O2 snow. i thought about wrist straps also, does anybody have a source?

December 01, 2012
by sask55
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well, as any Canadian old enough to have expriance using both the Farenheit and the celcius scales can tell you -40 C and 40 below F are the same temperature. If we take wind chill into conideration I have seen penty of -50 C days.

I made up my own wrist strap one day after I became frustated damaging anouther chip by simply touching the board.

I am send from a phone so may be more errors then from keyboard.

Darryl

December 01, 2012
by Noter
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I have never used a wrist strap and most of the time I don't even power off the circuit before pulling or inserting the chip. Probably not the best practice but I have not had any problems because of it. If you're worried about static just touch something that is grounded to discharge before you handle components.

December 01, 2012
by keith712
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Darryl, i'm feeling stupid... as soon as you said -40C = -40F i remembered that i used to know that...

thanks Noter, i'm going to touch my grounded lamp before i touch the ICs from now on just to be safer than i need to be...

i should probably start another thread or do a search in the forum but my next question is about the 120VAC to 9VDC converter that comes with the LED Scrolling Display kit. when i put my multimeter across the DC out i get 31.8VAC and 14.8VDC. am i doing something wrong?

December 01, 2012
by sask55
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Since I removed the carpet in the room it is much less of a issue. I am aware that I can ground myself and most of the time do. However there have been a number of time that one absent minded touch as I am thinking about makeing some simple change cost me a chip. As I said I became frustated with myself when I would neglect to do that very simple grounding touch. Enen in the event I noticed a very distinct snap of static when contacting the board most of the time nothing seemed to go wrong. A few times I clearly damaged achip as was not able to get them to work after the snap.

December 01, 2012
by Ralphxyz
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when i put my multimeter across the DC out i get 31.8VAC and 14.8VDC. am i doing something wrong?

With a multi meter there is no load so the out put will range up.

I think that if you you looked at the voltage under load you would find it was more in range.

I notice the same thing about the output, probable someone here answered the question.

Ralph

December 01, 2012
by keith712
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thanks Ralph, i'll check the output again when i set up the LED Array project.

December 01, 2012
by sask55
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Keith

This is a thread that goes into some cosiderable detail about power out from adapters.it was started with virutaly the same question you have. You may find some of it iteresting. AC/DC adapters Link

December 01, 2012
by keith712
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thanks Darryl... i'm still not good at using the search tool... i had given up searching for a thread on this... i think your analysis answers my question fully... when i use my 9VDC (LOL) wall wart i'll put a 6000+uf capacitor across the leads.

December 01, 2012
by sask55
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Your wellcome.

I often find Ansers can be difficult to find. I was certain that thread was posted here somewhere. I had some touble locating it even when I knew it was there.

This phone and I don't get along to well. To many typos and spelling errors even for me.

December 02, 2012
by Ralphxyz
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I often find Answers can be difficult to find. I was certain that thread was posted here somewhere. I had some trouble locating it even when I knew it was there.

That is exactly why I asked the Nerdkits guys for a Library.

Even though I did not originate the thread I have added a reference to the Library under Problems linking to the thread Darryl referenced, and contributed so helpfully to.

I know Darryl has contributed to the Library but I really want to highlight to others that everybody should be contributing to the Library, just links to forum references is a start and then hopefully someone might actually do an article.

So if you ask a question or add an answer worth remembering please add it to the library.

Ralph

December 02, 2012
by sask55
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Ralph.

I agree with what you are saying about posting to the library. There could and often should be more of it done. Speaking for myself it always seams that a post is somewhat incomplete or lacking in some way. It often seems that someone else will likely have better writing skills and technical knowledge. So I leave the seemingly more official and permanent library posts to someone better qualified.

December 02, 2012
by BobaMosfet
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sask55-

"Saskatchawan Canada. About as far from any sea coast or open water as you can get in North America,after freeze up. It tends to be cold and dry often for extended periods."

You might try running a humidifier to raise the moisture content in the air to about 27%.

BM

December 03, 2012
by sask55
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BM

Yes humidifiers do help somewhat. There is a limit of what can be added before the water starts to condense on the inside of the windows behind he blinds or curtains,which can lead to other problems, it gets to be kind of a balancing act. I think the issue was a very bad combination of the carpet in the room, my rolling office chair moving on and off a plastic floor protection sheet and very dry air. I have change to flooring, removing the carpet. I don’t get anywhere near the same level of static anymore. In fact I don’t notice any at all now.

When the carpet was in place and the weather conditions where dry in I could be almost 100% certain I would produce a sizable static snap every time I move a few feet across the room and touched anything. You may think with such consistency of static build up it would be easy to remember to ground myself before touching the board. Well I managed to prove it was not that easy, for me anyway. Occasionally I would be focused on some issue reach to switch the board to rewrite some code and snap I did it again.

Anyway, the underlying point is I know from experience that both the USB cables and micros can defiantly be damaged from static. In case someone is not aware, static discharges to the nerdkit board dose not always result in damage but it certainly can.

Darryl

December 18, 2012
by alex555
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I have worked with many CMOS ships and never had a problem. I also build all of my circuits live, which probably isn't to great, except when you are debugging.

December 18, 2012
by JKITSON
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For years I have used a 50/50 mixture of DOWNY & water. Use a spray bottle with a very fine/mist spray. I spray the carpet about twice a month in the winter and maby once a month in the summer. I live in Arizona where it is very dry & lots of static. Works for me and a number of my customers.

Jim

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