5 ms·

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

by fvox13 13y ago

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.

joezydeco 13y ago
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.
- throwaway1979 13y ago
  Good point. Any idea what ballpark speed one would need?
  - tcas 13y ago
    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.
    - asynchronous13 13y ago
      But, you can make your calculations massively parallel on an FPGA. So the clock speed does not compare at all to a typical processor.
- jff 13y ago
  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.
- dfox 13y ago
  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.
shabble 13y ago
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.
- sounds 13y ago
  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.
Florin_Andrei 13y ago
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.

by fvox13 13y ago

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.

joezydeco 13y ago

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.

throwaway1979 13y ago
Good point. Any idea what ballpark speed one would need?
- tcas 13y ago
  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.
  - asynchronous13 13y ago
    But, you can make your calculations massively parallel on an FPGA. So the clock speed does not compare at all to a typical processor.
jff 13y ago
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.
dfox 13y ago
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.

shabble 13y ago

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.

sounds 13y ago
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.

Florin_Andrei 13y ago

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.