Harvesting components from devices

Hey guys;

I just discover today a new way <-- well I read this in a magazine to remove / desolder the parts including SMT. Since CrossRoad told me about Rosin Flux for soldering, I deside to use for desoldering. I have a copper braid, and I apply the flux at the copper braid, place the braid at the solder joint, heat the joint and the braid and... :open_mouth: the solder was absorbe by the copper braid realy good.

I just want to share this tip, when you desolder parts for harvesting. Because on some boards, it is hard to get the parts. even using a desolder pump.

I want to share a method I discovered to test power transformers: the other day I was "dissecting" an old UPS that had a big transformer inside. The lower voltage part was easy to identify, since it had thick cables (it's a 1000va UPS, so the transformer is rated at about 5A I guess), but on the other side there were many cables on the primary. Following the circuitry I was able to identify the "Neutral wire", all the others were in series with the first one. Tested them with the ohmmeter, and there was just an Ohm difference between them.

Now to the idea worth sharing that I found on a Spanish site: I used an electrical incandescent bulb of 100W in series (on the "live" line) and connected it to the other cables, then measured the voltage in the secondary when trying different combinations. This way, if I shorted by chance the test leads, the bulb would glow and nothing would get burnt.

Ok, I had a good time reading the posts here.
For the original question: Save whatever you think it will be useful. Space is a concern so I tend to desolder the parts so all stuff waste less space and donā€™t need to keep stuff I think I will not need.

My wife is so pleasant to remember every time, when she was my girlfriend at the uni I had a small bag with all piece of clothes and a big suitcase full of wires and stuff.

1-> Wives in general donā€™t take well all the stuff husbands stores, classified as just "trash" but they donā€™t know from where comes all the stuff we use to repair stuff ! I think they will never understand the logic :stuck_out_tongue:
2-> If you keep a thing for 10 years, even a insignificant piece of stuff, and throw away some day, you will need that piece of thing in the next week.
3-> Of course we cannot keep all the parts we want to keep ? thereā€™s just no space for everything.

Salutations

DanDare:
1-> Wives in general donā€™t take well all the stuff husbands stores, classified as just "trash" but they donā€™t know from where comes all the stuff we use to repair stuff ! I think they will never understand the logic :stuck_out_tongue:

Every time I complain about not having enough room for my stuff (or having too much "junk"), my wife says she knows just what to do to get everything organized (ie, throw most of it away).

DanDare:
2-> If you keep a thing for 10 years, even a insignificant piece of stuff, and throw away some day, you will need that piece of thing in the next week.

This is the truth - there's been things I've gotten rid of that I wish now I hadn't...oh well.

DanDare:
3-> Of course we cannot keep all the parts we want to keep ? thereā€™s just no space for everything.

I do my best, though; I have my shop and the attic space above it to store most of my junk; the rest is in my office (a spare bedroom in our house), and some larger things (an RL-500 robotic mower awaiting repair, a powerwheels ride-on quad for a robot chassis, and an old CD-ROM server chassis) sit in our garage (we use it as storage, as it is a converted carport that none of our cars will fit in).

I have found a different trick, though: A lot of stuff I bring home tends to come from the same place; a local electronics junkyard known as "Apache Reclamation and Electronics" here in Phoenix. I've been going there for 20+ years. Anyhow, some of their more obscure stuff has a very low turnover rate; some items there almost never move. So I use them as "storage": I note something that I think will be useful, then when I really need it, I purchase it. Generally, this works out; rarely have I passed something up that didn't stay there for a good 5 years or more (I'm still eyeing that industrial metal cutting laser they have - I just don't have the three-phase to run it!)...

:smiley:

A few months ago, near a garbage bin at a Elementary Public School, I pick-up this metal storage.

Here a picture.

Techone:
A few months ago, near a garbage bin at a Elementary Public School, I pick-up this metal storage.

Nice find! If you subdivided those drawers, you could have one heckuva parts storage cabinet! :smiley:

Oh.. yeah... I already started to fill up with stuffs like... Motors, Step-motors, heatsink, Ardiuno Sheild + DIY ( I include a big pink anti-static foam ) , Arduino boards with a anti-static foam, Battery holder, transformers, speakers, LCD display with a pink anti-static foam, big variable capacitors.... :sweat_smile: Rooms for more... XD

Thank for you comment... That one advantage when you drive a mini school bus, you do see "garbage" along the way...

If you subdivided those drawers, you could have one heckuva parts storage cabinet

Oh.. I see.. that is a great idea... :open_mouth:

Techone:
Oh.. yeah... I already started to fill up with stuffs like... Motors, Step-motors, heatsink, Ardiuno Sheild + DIY ( I include a big pink anti-static foam ) , Arduino boards with a anti-static foam, Battery holder, transformers, speakers, LCD display with a pink anti-static foam, big variable capacitors.... :sweat_smile: Rooms for more... XD

Thank for you comment... That one advantage when you drive a mini school bus, you do see "garbage" along the way...

I'm a master scrounger myself - always on the lookout for junk along the side of the road (I have a pickup so stopping and throwing it into the bed is never an issue).

:smiley:

Techone:

If you subdivided those drawers, you could have one heckuva parts storage cabinet

Oh.. I see.. that is a great idea... :open_mouth:

Thinking on it a bit more: If you can find some cheap multi-compartment flat boxes with lids that will fit inside the drawers, then you could pull a single box fairly easily (plus, you could use a label maker to put labels on the lid for each space to know what was what).

@cr0ch

Explain this to me. I was driving with the bus ( 4 kids on board ) and near where I live around 3 PM, I saw a TV on the curb, ( I will pick-up later - I said to myself - not with the bus with kids ) I came back around 6 PM and .... :fearful: Gone... NO TV ... GONE... What the ... ? Gone that fast ? It is people in my neiborhood like to take garbage too ? e-garbage too ? Man.. I hated that ... :0 Beat me to it...

I too love to take dead devices apart... first with the hope towards arepair, second with an interest in how it was made, third to harvest components if it's truely dead.

If you're looking for high-voltage transformers, BTW, microwave ovens are a great source for them unless it's an "inverter" model. Some folk have used multiple microwave transformers in series to do stick welding projects.:fearful:

I expect these analog devices to disappear from microwaves over time thanks to the commodity price increases combined with a steady decrease in transistor prices. Just like the classic transformer/bridge rectifier/linear VR/smoothing cap circuit we used to see in all appliances..

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"??

@pgmartin

For transformers, the secondary is usaly a heavy gauge wire, the primary a thinner wire. Except, when the secondary is higher voltage type, well, the secondary will be thinner and the secondary will be heavier. And I sometime use a ohm meter to test them. And if I fell "safe", then I do a power test and measure the output wire to see what I got.

Here a picture of a transformer I harvest. Still did not measured yet...

Here a picture of more parts to harvest. Some of the boards, it was in the backyard shed for years, and a few "new arrival " board in. That will keep me busy. Most of them, from the garbage. So I call it ---> Free parts .... XD

Sorry for the mess... :blush:

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!

pgmartin:
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.

Lefty

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.

Lefty

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. :slight_smile: 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.