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Author Topic: Techniques for finding salvaged parts values  (Read 7838 times)

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cream

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Techniques for finding salvaged parts values
« on: January 07, 2015, 03:03:01 AM »
Hello,

I found this site through a search on salvaging parts from old electronics.  Now that I know how that is done.  I am wondering what are some of the ways for us to get the values for some of the surface mounted components that can be salvaged.  As far as i can tell these parts do not have markings (unless maybe i need a magnifying glass to see them, have not tried that).  Are there any good techniques or methods for finding these values? 

Thanks!

kam

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Re: Techniques for finding salvaged parts values
« Reply #1 on: January 07, 2015, 16:20:49 PM »
SMD parts with no markings are usually capacitors, some small resistors, maybe inductors... The energy required to desolder them is more expensive than to buy them.

Anyway, first you need to guess what sort of component it is. Then, you use your RCL meter to find out its value. Or it could be a diode but diodes have always a cathode marking.

As far as the transistors are concerned (SOT23) most likely you cannot get any info for them.

cream

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Re: Techniques for finding salvaged parts values
« Reply #2 on: January 08, 2015, 16:08:49 PM »
Hello KAM and thank you for your reply.  The LCR (RCL) meter is exactly what i was missing.  I did not realize that these existed.  I will have do some research and find out what the full capabilities of the meters, but clearly that is what you need to get it done.

I have to say, however, I am a bit surprised by the first part of your reply.  Was it not your video on youtube that lead me here, talking about how great it is to salvage the parts, and minimize e-waste? 

Also, correct me if I have my math wrong here (seriously, I want to know if i have this incorrect), but a 2000W heat gun running for an hour would cost me 2kWH of power from my electric bill.  Currently (prices just went up for the new year, yay!) the price for power from my provider is 7.6 cents per kWH.  Assuming that we ran the gun for a full hour at full blast, that would cost 15.2 cents.  I just placed an order through digikey where granted, i did not buy in bulk and was able to custom select each individual component to my projects exact specifications, but still, the order was about 100$ for 2 projects.  I can not help but think that the 15.2 cents on salvaging parts for small learning/tinkering projects would be greatly worth it.  Especially considering that I have a stack of old computer motherboards that I just have not been able to bring myself to throw away over the years. 

I guess there is one piece of information here that I am not sure about.  How much time does it actually take to strip a board down?  Then test and sort the components, after that...  I could see that adding up, but i am a student at the moment and the time might still be worth it to me.   

kam

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Re: Techniques for finding salvaged parts values
« Reply #3 on: January 08, 2015, 21:11:08 PM »
Well, you can ebay a resistor SMD set for 1.5 Euro 4000pcs...
http://www.ebay.com/itm/400-pcs-set-0805-SMD-10-1M-20-values-Resistor-Package-Kit-Set-/121403554830?pt=LH_DefaultDomain_0&hash=item1c44373c0e

And another 8 euros for 1140 capacitors...
http://www.ebay.com/itm/57-Value-0805-SMD-Ceramic-capacitor-MLCC-SMT-KIT-1140PCS-/260854044143?pt=LH_DefaultDomain_0&hash=item3cbc1cd5ef

Another 0.85 Euro for 100 transistors MMBTA2222
http://www.ebay.com/itm/100PCS-MMBT2222-SOT-23-2N2222-SMD-NPN-Transistor-New-/321489835084?pt=LH_DefaultDomain_0&hash=item4ada49944c

As long as you know what you want to buy, you can find those parts cheap on ebay.

There are though parts worth to salvage for 2 reasons:
1. They are rare or expensive
2. You can stock parts that you do not need today, but one day....

Electrolytic capacitors are usually quite degraded from use, so i recommend you do not keep them unless you want them for artistic reasons. Also, you have to keep in mind that thermal shock is a degrading factor.

As for e-waste, you are absolutely right.

But the greatest gain when salvaging parts are not the parts themselves. Instead, its the process. Take your time when removing the parts form the PCBs. Google the ICs before removing them and then check how the professionals use them. Every time you will learn something new.


P.S. I always keep salvaged power inductors and chips. Also, I keep all the connectors. These are parts that most likely you will use in the future.

cheerio

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Re: Techniques for finding salvaged parts values
« Reply #4 on: January 10, 2015, 14:05:34 PM »
"7.6 cents per kWH"
omg that is so awesome... 0.25EUR/kwh here

kam

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Re: Techniques for finding salvaged parts values
« Reply #5 on: January 10, 2015, 21:21:09 PM »
What the.... You said 0.25 EUR/KWh or you mistyped???? That can't be right. I payed 0.0661 /KWh last time.

cheerio

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Re: Techniques for finding salvaged parts values
« Reply #6 on: January 10, 2015, 22:56:30 PM »
it is 0.25EUR/kwh. no fission energy, just renewable energies. and Germany is expensive as shit when it comes to energy...

kam

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Re: Techniques for finding salvaged parts values
« Reply #7 on: January 11, 2015, 12:54:43 PM »
Is it all renewable energy? I mean 100% wind/solar? No coil? No other means of fossil fuel?

cheerio

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Re: Techniques for finding salvaged parts values
« Reply #8 on: January 11, 2015, 16:32:13 PM »
yes. hence it is a bit more expensive. not so much renewable -> ~0.2EUR/khw
check it all out yourself:
http://www.toptarif.de/stromweb/wicket/page;sid=ff567cfb-3bd7-44b9-bcfc-c97b2e1720a5.uuid,aa6eab95-9ecd-417f-b3fe-05a843844e84.cmsproxy,cms001.electricity,ele002?3&qaywsx=
price per kwh is shown when you hover the yellow price tag

kam

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cheerio

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Re: Techniques for finding salvaged parts values
« Reply #10 on: January 13, 2015, 23:10:43 PM »
oh it was a session in there

http://www.toptarif.de/

just use 65343 as the zip code (postleitzahl)