Scavenging to sustain the habit
Parts are expensive unless you buy in bulk, and even then, you may have an issue. However, many parts, like tantalum caps, bypass caps, crystals, and inductors are everywhere in old equipment. As it turns out, as an IT guy, I inherit a lot of old equipment….
Old motherboards are at the pinnacle of technology for the time. They have lots of precision power circuitry on them and that means high-quality caps and filtering components as well as switching power control circuitry.
Take this motherboard from a Watch Guard firewall appliance for example:
It’s a socket 7 system with a few BGAs and some other connectors. This was a throw away from a client that needed to be wiped and disposed due to having a lot of private keys on it. While, nuking it from orbit would have been fun, I saw a large complement of useable parts on there. So I wiped it with the jumper, then removed the NV RAM using a hot-air pencil.
Now, down to business. Let’s look at the loot…
|Qty||Desc||Price low||Price High||Total||Column1|
|10||22uF 25V Tantalum Capacitors||$ 0.35||$ 1.20||$ 3.50||$ 12.00|
|13||Unknown Tantalum Capacitor||$ –||$ –|
|8||F6680 n-MOSFET||$ 0.33||$ 0.82||$ 2.64||$ 6.56|
|1||Altera EMP3032A CPLD||$ 5.00||$ 6.00||$ 5.00||$ 6.00|
|2||74F14||$ 0.25||$ 0.90||$ 0.50||$ 1.80|
|1||LTC1709 sync step down converter||$ 5.60||$ 10.35||$ 5.60||$ 10.35|
|1||LTC1628 switching regulator||$ 5.20||$ 9.33||$ 5.20||$ 9.33|
|1||LTC1337 3TX 5RX rs-232 tranceiver||$ 5.30||$ 9.20||$ 5.30||$ 9.20|
|3||Atmel 93c46c Serial eeprom (1Kb)||$ 0.17||$ 0.32||$ 0.51||$ 0.96|
|30||10uF 16V Tantalum Capacitors||$ 0.30||$ 1.30||$ 9.00||$ 39.00|
|4||Current Sense resistors||$ 0.19||$ 1.00||$ 0.76||$ 4.00|
|3||Crystals||$ 0.25||$ 1.00||$ 0.75||$ 3.00|
|1||Oscillator||$ 0.50||$ 4.00||$ 0.50||$ 4.00|
|3||Ethernet connectors with magnetics||$ 6.78||$ 18.00||$ 20.34||$ 54.00|
So on the low side, about $60 worth of loot from a worthless bit of equipment.
That table only tallies up the stuff actually worth anything. I still got a ton of 0603 bypass caps and resistor arrays as well. Now, were they worth getting? If it means not having to pay for shipping, or waiting for stuff to show up, then yes. Most likely, no.