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Topic: Harvesting components from devices (Read 48896 times) previous topic - next topic


In Brazil we have a kind of surge protectors that we call Stabilizer. They are useless to nowadays computers and electronics but people keep buying those, thinking they are protecting their computers. They look like UPS as this one:

They usually contain relays inside, with a comparator that checks if the mains voltage is over or under what is intended to be.
So its nice to harvest the little control board. Rip off the comparator IC and you can identify the transistors that powers up the relays. Feeding the board 12vdc will sometimes power up a led and feed the transistors collectors. Connect the digital out pin from the arduino on the transistor base and you have a nice relay board. Usually you find 2 relays with two transistors controlling them, so you get a relay board for free. You also get a comparator IC like the LM324 that I'm sure you can think a use for that later!


When it come to harvesting transformers and motors many times I face the question of how many amps (transformer) and voltage (motors) can they handle.
in the case of transformers, I usually try to get a glance of the wire in the secondary spool and then do the guessing work. Before using them, I'll connect them and see how hot they get and if there is not much humming sounds.
Does anyone have suggestions about it? Is there a way to test them more "scientifically"??

I recall a estimating method used in ham radio to characterize unknown transfomer ratings years/decades ago. First one tries and find/measure/estimate the cross sectional area of the internal metal core that the windings are wound on. With that value and a proper graph/chart one (an old ARRL manual had one at one time) one can estimate the maximum wattage of the transformer. Once you know the wattage then one can measure the secondary winding voltage and then have all the variables needed to calculate the maximum secondary current available from the transformer's secondary winding. It can be a little time consuming but can save many dollars if a surplus or free transformer can be utilized over having to buy a new one with published specifications. Of all the standard electronics components, 60/50 Hz power transformers are probably the only component that costs more today then they did years/decades ago. Raw material costs directly effect transformer costs and they have (copper and iron) only gone up in price.



I've also seen the phrase "20 Watts per pound" thrown about but haven't personally put too much faith in it.

Might be valid. I recall decades ago comparing 60Hz power transformers shipping weight Vs total wattage regardless of secondary voltage in say a Allied Electronics catalog and seeing a good correlation.



Hi there, another hardware disassembler on the forum. I love to take apart electronic stuff too. However I have the same problem with my wife as the guys here. So, I take them apart very fast and dump the not so importand stuff at the municipal recycling dump store and save the important parts in boxes. Mostly printers and old TV's. The older ones have discrete components to handle. The newer TV have components I cannot handle anymore because of the ongoing miniaturisation.  :) So DIP parts are welcome on the boards.
So today is a disassemble day. Taking 3 old Dell computers apart. My first Dell from 2001 and several others from 2006.

I use the sensors (infrared, humidity, temperature) I find in the scrap for my Arduino projects.

Hmm love it.


How about old microwaves?And make your own mini welding station. Careful, high voltage in the microwave. Go to YouTube of google up Sam Wasserman's electronics site and you will find how to safely remove the items for building a welder and ideas for other projects.

I learned my soldering skills through massive de-soldering sessions. If you can successfully de-solder components on a PCB, if becomes easy to assemble and solder another.
I also used the carcass keeping the light bulb, adding a simple switch and that rotating base motor and I how have a great spray booth!


when i salvage, i always try to keep everything removed from the one device in the same box, and if necessary label cables that connect different individual circuit boards.

electric motors, quartz crystal oscillators, electrolytic capacitors, IC's, MOSFETS.

Take apart the very inside guts of one of those old A: floppy drives and you will find an awesome little guy, i dont know what its called but its basically a ring of small inductors enclosed inside a magnetic rotational enclosure. Im sure it had some purpose concerning writing to a floppy disk but if you pull it out and put it in a circuit on a bread board it can be used as a potentiometer but one which varies the potential by increasing/decreasing the inductance of the circuit instead of the usual variable resistor type, which i though was cool.
im a good observer. not the brightest but very curious.

that poor innocent dog died from AC. he died.

I do not refuse my dinner simply because I do not understand the process of digestion."

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