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It's kind of funny; I came out of school ready to design circuits with discrete transistors and they laughed at me. "Sure, that can work, but it will definitely

It's kind of funny; I came out of school ready to design circuits with discrete transistors and they laughed at me. "Sure, that can work, but it will definitely work if you use this opamp." Much like we caution people not to write assembly, because the compiler can do it better. But sometimes it can't. Sometimes the opamp designers made choices I would not prefer for my circuits. To me it's funny how after all this time, I've only recently started to consider transistor-level design again. I suspect it's a deeper understanding of the tradeoffs than I had as a novice engineer. Or hubris, thinking I can do it better. There absolutely isn't a practical alternative for low volumes, there's barely even one for medium volumes. There once were IC houses with semicustom parts - they had a variety of transistors, resistors and maybe a few (really huge bipolar) gates onboard, and you could design the metal layer, resulting in a single custom mask on an otherwise standard product. Actually, Astec still has one, Device Engineering offer one, but there's not a lot out there. This was always a niche business anyway. So yeah, it does seem obvious that we should design from discretes, actually crawl into the boxes in our block diagrams and build the things in there from scratch. But it's funny how easy it can be to stop doing that, to just find a single chip/module that does it all. And it's been amazing to me how well the IC market has mapped out to what I have needed over the past several years. Every time I've tried to build something, I found I could just buy it. Eventually, you think "buy" before "build." For me, it's taken extra effort to consider "build" first anymore. Just like the author found, it's fun, too. Just buying that ublox GPS chip is okay, but building the parts I need is cool.

JamesBryant 6y ago
But don't waste time reinventing the wheel. I needed a small audio amplifier the other day and looked for an IC to build it. My junk box was empty of audio amplifiers so I went to a distributor and found a nice IC for 65p but minimum order 10 off. With postage the price was about £10, and I still had to find the other components and build it. I was just about to order it when I realised it might be cheaper on eBay. There a found an assembled board with the same amplifier for 56p with a minimum order of 5 pieces:- £2.80 post paid and ready to use - and four spare ready-made amps for future projects. Beating the system is fun, too.
- kevin_thibedeau 6y ago
  The eBay sourced chips are likely counterfeits that won't meet all the specs.
  - omgwtfbyobbq 6y ago
    In my experience the random stuff I buy off of whatever $Auction_Site seems identical to what I buy from $Local_Vendor, but with no QA or packaging. The defect/failure rate is higher and it takes a lot more time to arrive, but the cost is significantly less. It's possible that there are more counterfeits, but I don't think the stuff off of $Auction_Site is likely (>50% chance) to be a counterfeit just because it's from $Auction_Site.
    - kevin_thibedeau 6y ago
      If it's a chip that you can search for in a product description it has a high enough profile to be an SZ fake. See this example of a fake signal gen IC that almost works properly: https://www.youtube.com/watch?v=02XtneCHnDA https://www.youtube.com/watch?v=02XtneCHnDA Add in a price that's too good to be true and the odds go up.
      - omgwtfbyobbq 6y ago
        I can see that. I've purchased several laptop batteries that likely used old cells pulled from another laptop or whatever. At the same time, I don't mind that the runtime is a 1/2 to 3/4 of a new battery when the price is 1/5 of a new battery.

JamesBryant 6y ago

But don't waste time reinventing the wheel. I needed a small audio amplifier the other day and looked for an IC to build it. My junk box was empty of audio amplifiers so I went to a distributor and found a nice IC for 65p but minimum order 10 off. With postage the price was about £10, and I still had to find the other components and build it. I was just about to order it when I realised it might be cheaper on eBay. There a found an assembled board with the same amplifier for 56p with a minimum order of 5 pieces:- £2.80 post paid and ready to use - and four spare ready-made amps for future projects. Beating the system is fun, too.

kevin_thibedeau 6y ago
The eBay sourced chips are likely counterfeits that won't meet all the specs.
- omgwtfbyobbq 6y ago
  In my experience the random stuff I buy off of whatever $Auction_Site seems identical to what I buy from $Local_Vendor, but with no QA or packaging. The defect/failure rate is higher and it takes a lot more time to arrive, but the cost is significantly less. It's possible that there are more counterfeits, but I don't think the stuff off of $Auction_Site is likely (>50% chance) to be a counterfeit just because it's from $Auction_Site.
  - kevin_thibedeau 6y ago
    If it's a chip that you can search for in a product description it has a high enough profile to be an SZ fake. See this example of a fake signal gen IC that almost works properly: https://www.youtube.com/watch?v=02XtneCHnDA https://www.youtube.com/watch?v=02XtneCHnDA Add in a price that's too good to be true and the odds go up.
    - omgwtfbyobbq 6y ago
      I can see that. I've purchased several laptop batteries that likely used old cells pulled from another laptop or whatever. At the same time, I don't mind that the runtime is a 1/2 to 3/4 of a new battery when the price is 1/5 of a new battery.