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General Electronics Chat This forum is for general chat about electronics, eg: Dont know what a part does? Dont know how to read a circuit? Want to get an opinion?

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Old 15th June 2008, 10:49 AM   (permalink)
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Originally Posted by Mikebits View Post
I guess my point was, it is nicer to use an expendable PC for projects than your main use computer. I am sure the odds of frying a PC are slim, rather than just an interface card, but why chance it if not needed?
Yes and if you use a USB based programmer the chances are closer to none.
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Old 15th June 2008, 02:06 PM   (permalink)
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Why use your main and expensive PC to program PIC's? Better to lose a $100. laptop than your business end of computing.
I would get an extra PC to open PDF files then, because Adobe software damages my PC more than any tools I use for micros.

Seriously, though, this is not a concern, so have no fear on this.
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Old 15th June 2008, 02:13 PM   (permalink)
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I've used ATX supplies in a professional lab environment. One advantage is the other engineers are less likely to steal them.
ROFLMAO
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Old 15th June 2008, 03:11 PM   (permalink)
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Why would you lose your computer? Is it possible to damage your computer when programming PICs!? If so, do the programming kits such as Junebug and PICkit2 come with some sort of "fuse" to prevent damage to your computer? If not, then I guess I will have to whip out my 9 year old Gateway desktop computer that has been accumulating dust in the corner of my room
I would assume that the usb controller/module would fail and end any issues then and there. I can tell you that the AVRISPMKII (usb programmer) for AVRs has protections to guard against this, and even allows shorting and improper polarity wiring as included safeguards. If you do program, think about AVRs, only took me a week to master most of my AVR's peripherals and functions after having only a semester of a microprocessors class. (I went from using 68HC11s)
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Old 15th June 2008, 04:55 PM   (permalink)
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Henry, ATX supplies are short circuit protected. I've never tested the +3.3 volt lines on mine, but tested both the +12 -12 and +5 main lines. I've plugged an RS232 board accidentally inverted into my PC, so it's 24 volts, power supply 'clicks' and humms in shutdown but no damage to any circuits. I wouldn't rely on it for 'serious' current limiting, but for a hobbyist it's wonderful.
Was there a diode in series with the power supply? Then of course there isn't a problem, but if it's not...
An ATX-power supply can deliver what? like 20Amps at 5V or something, imagine 20Amps going through a little beginners circuit. Off course it is easy for testing and as long as you don't screw up big time, you'll be fine, but the moment you need a GOOD power supply, no ripple, no HF-junk, I think it's better to invest in a good power supply...

LM317's can take everything, as can 78xx, they are better protected than you could imagine, current limiting, thermal safety shutdown, maybe oscillation will get it to go sky high, but i never ran across that..
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Old 15th June 2008, 07:20 PM   (permalink)
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Henry... ATX power supplies are short circuit protected. Better yet they're DV/DT limited. You can't just slam a 20 amp load onto an ATX supply no matter what it's max current output is it'll shutdown asuming a short, current has to be ramped up. I'm a little surprised you're taking hits at ATX power supplies, they run almost every home computer in existence and the majority of PC failures have nothing to do with the power supply. I've also never heard of an ATX power supply bursting into flames unless tampered with to deliberately malfunction. The modifications to an ATX power supply for use as a hobby supply doesn't fundamentally alter any critical component of the supply.
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Last edited by Sceadwian; 15th June 2008 at 07:22 PM.
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Old 15th June 2008, 07:41 PM   (permalink)
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I didn't say anything about the ATX bursting in flames, but the circuit on which you're working...
They are used in computers, because that is what they are made FOR, and imagine if you have a few HDD in your computer and they all fire up, imagine what kind of current goes through that? Yes they are short circuit protected, but that doesn't take away the fact that they can deliver HUGE currents.
ATX power supplies have proven their usability, in Computers, let them be there, they are designed for computers. I am not taking hits at the ATX concept, just the thought of a ATX power supply in a (for instance) breadbord circuit doesn't make me feel happy...

But if you want to use an ATX for something, I won't stop you, besides, NY is a bit out of the way for me to be doing with my bike
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Old 15th June 2008, 07:55 PM   (permalink)
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I didn't say anything about the ATX bursting in flames
Dutch company I was working for had the problem with ATX PSU bursting in flames .. over 30 times .. We had ~200 computers .. in timespan of 6 months over 30 of them "exploded" .. "bursted in flames" .. etc.. one managed to output 10-15cm flame out the fan while I was holding it !!!

So, "good" PSU from "good" manufacturer will have "good" protection, but those 3-10$ PSU's can do many "interesting" things ... like burst into flames, shoot capacitors trough fan etc..

One "interesting" thing is that from those ~30 PSU "explosions" ~15 times no damage was done to the computer except that PSU had to be replaced, in other ~15 cases EVERYTHING (including keyboard and mouse) except CRT monitor was fried.

I personally use ATX PSU as hobby power supply as I have many of them and that is cheapest way to have ... but ... they can go kaboooom, I know, I saw it too many times
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Old 15th June 2008, 08:02 PM   (permalink)
Default Laptop for PICs, and cheap digital Tektronix scopes.

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Why did you have to buy a $100 laptop to program a PIC?
The (very good) free development environment that Microchip supplies (MPLAB) only works under Windows. I owned a Mac. So, I bought a 100 dollar laptop, windows 2000, 400MHz. That's the only reason.

Back on topic: I don't know about other programmers etc. I just wanted something that worked seamlessly. Let me put it this way; I'd rather pay an extra few dollars, or do the boring/simplest thing, than spend an afternoon fiddling around with software/hardware compatibility issues. Everything I use that's PIC-related is from Microchip, and apart from one add thing (why is 16F54 programmable in Pickit 2 application but not MLAB?) everyhting has run absolutely seamlessly. For books I recommend (as do many others) Morton's introductory book, and of course printing out a couple of PIC datasheets. I'm enjoying PICs immensely.

After studying the Tektronix website, it became clear that there were only a couple of digital Tek scopes I could afford. If you ebay it, google 'TDS 220 recall' or whichever you find, because there was a recall for some of them. 500-600 bucks for any of the B&W Tektronix digital scopes is a typical price. I've seen TDS 1002 for same price as 220, so you might keep an eye out for 1002 models. Slightly better. In the long run +/- 50 bucks is not to be worried about. Worse things happen (to oscilloscopes) at sea.
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Old 15th June 2008, 09:45 PM   (permalink)
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My last mention of ATX. Henry, I've on multiple occasions dead shorted the +12 volt line to a solid ground with heavy wire, nothing but a tiny arc before the supply shuts down. I've used it on my breadboards since I've owned bread boards, many dead shorts, no part failures of any kind, and as I've said, I hooked up my STK500s power leads wrong and it was running off of a -12 volt supply when I hooked up the RS232 to my PC (+12) and the power supply shut down, I did this over a dozen times before I realized what was wrong. STK500 and PC were both fine and no glitches aside from power loss. They are as intrinsically safe as you can get in a power supply. Many professional power supplies would not shut down under the same circumstances as an ATX supply would, in fact I hear this is a problem with some people using them for high power PWM as the DV/DT the PWM places on the line shuts the power supply down, they have to use load resistors before large electrolytics to buffer the power line enough to let them draw the high pulse currents.
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Old 15th June 2008, 11:40 PM   (permalink)
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I've used an ATX as a power supply in a professional environment. It was at a company that spent no money on our department though.

Last edited by speakerguy79; 15th June 2008 at 11:40 PM.
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Old 16th June 2008, 06:28 AM   (permalink)
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I wont use ATX power unit as a desk power supply.I also have blowed up many after short circuit in the outputs.Not all power units protect them well against short circuitry.

For a hobby desk power supply 500mA - 1A small transformer supply is more than enough.Regulated output its upto you.If needs variable then variable, if needs dual +/- polarities then make like that.
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Old 16th June 2008, 06:46 AM   (permalink)
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What are you planing to make/repair in your hoby

power supplies i would make myself more than one always handy

function generator i also would make my self also

a multi meter buy a good one if you're realy serious to stay in the electronics (fluke) but buy also a extra cheap one on top of it
more than one to mesure simultaniusly is very handy in some ocasion

soldering station yes it makes life so much easyer

computer

scoop is handy but i have to say that i work already years without one and still doing fine

depens what you do in the electronics

Robert-Jan

Last edited by rjvh; 16th June 2008 at 06:47 AM.
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Old 16th June 2008, 08:06 AM   (permalink)
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You must visit this thread also,it contains the electronic workbenches of electro-tech members.

http://www.electro-tech-online.com/c...workbench.html

You can get ideas that what they have & need to buy for your one.
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Old 16th June 2008, 01:20 PM   (permalink)
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What are you planing to make/repair in your hoby
I just plan on making basic circuits. From audio circuits (I made a stereo audio amplifer with two LM386N) to radio circuits (I am planning on making an FM transmitter) to even sensor circuits (want to make an IR alarm). Stuff like that. I am just starting off so nothing well be too complicated.
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