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Comment by fvox13 | Hacker News Reader

Sure, he designed it, but I don't think those nice printed PCBs are "homemade". I'd be more impressed if it were through-hole construction. Still, it's pretty cool.

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What are you, Etsy? :P

He didn't fab his own silicon, package his own dies, or even machine his own connectors!

The hard (and interesting) parts are the design and testing/debugging phases. Building your own PCB to handle various RF signals at this sort of level is non-trivial in both time and money, and doesn't really gain you much.

There's no reason why it should be through-hole either, and indeed, good luck finding suitable parts in those packages. SMD manual soldering isn't particularly hard either, although time consuming. If you have a reflow or spare toaster oven, you can do it a whole lot faster too.

I do agree, but to be fully pedantic,

  L1 and L2 are hand-wound microwave chokes with
  very high self-resonant frequency, mounted
  perpendicular to one another and clear of the
  ground plane. Wind 14 turns, air-cored, 1mm
  inside diameter from 7cm lengths of 32swg
  enamelled copper wire. Checked with the tracking
  generator on a Marconi 2383 SA, these were good
  to 4 GHz.

Doubtful you can get an FPGA of that class in a thru-hole package. The dude was smart to shop out the PCB instead of spending weeks trying screen and drill his own.

You probably can get FPGA in CPGA package that has similar performance to that Spartan3, but these things are meant for high reliability and wide temperature range military/aerospace applications (you get either THT or really funky SMT packages there) and certainly beyond the budget of most hardware companies, not to say any hobbyist.

Not like it's really that hard to solder SMD. I soldered 40-pin SMD all the time with nothing more than a fine-tip soldering iron, a syringe full of flux, and a magnifier or microscope.

Good point. Any idea what ballpark speed one would need?

Speed of the FPGA? FPGAs are given speed grades, but the actual design dictates the max speed. Different logic sections, depending on pipelining, size, which pins they are connected to can run at different speeds. You might have an overall max speed/critical path of say 50mhz, but you might be able to safely run a small section of the design at 200mhz.

But, you can make your calculations massively parallel on an FPGA. So the clock speed does not compare at all to a typical processor.

I've designed, drawn, corroded, and soldered entire soundcards, synthesizer blocks, and various systems with microprocessors, back in the day. All by hand.

To quote Linus, it's quite "studly" to operate like this, but the result is big and ugly. Fabbed PCBs are much more compact.

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