Hi Craig,
> Thanks super for the detailed post, David (and for the tip, Mike)
>
>> Fairchild and TI have many parts that'll work. I'll often
>> use TinyLogic parts from Fairchild as I can scatter the
>> bits around where ever I need them (makes layout dead easy),
>> and they're tolerant to voltages up to 6V.
>
> Would you be so kind as to give me a couple of part numbers so that I can
> check out the specs?
How about circuit examples instead:
http://www.ovro.caltech.edu/~dwh/carma_board/gda06rb004_carma_v0.87_dec03.pdf
p12 U38 NC7SZ125P5X tri-state buffer.
- 3.3V pull-ups on the input also route to a 3.3V FPGA.
- the output is pulled up to 5.5V
- the buffer protects the 3.3V FPGA
p12 U100 NC7SZ125P5X
- buffered signal to increase current drive to multiple loads
p13 U62 NC7SZ384P5X
- bus-switch
- 5V or 3.3V signal to 3.3V signal level bidirectional level
shifting
- the bus switches are disabled until the board power is
good
There's a bunch of other parts in there too.
Pericom, TI and Fairchild also have LPT and LCX series parts,
and I believe they're 3.3V powered, but 5V tolerant.
You can use their parametric searches to figure that out.
> I've hand soldered SMT devices to boards, but you describe
> a technique that I haven't used--"use a flux pen to wet
> solder wick and use that to remove the excess solder from
> the pins". That sounds really clever--how exactly to you
> "wet solder wick?" I've been trying to be so compulsive,
> this may help my sanity ;)
Using a flux pen (looks like big an indelible ink marker,
or yellow highlighter pen) you physically dab the pen
on the wick (the copper braided stuff, make sure to
use a thin version), and then its wet.
Now when you touch the soldering iron to the wick, which
is in turn pressed into your horror of a soldering job,
the solder reflows into the wick, leaving just enough
on the pins to keep the part happy, but the shorts at
bay :)
>> Even knowing about solder-mount pads, I would generally
>> not use them anymore. I find it much simpler to layout
>> a simple PCB with headers, and whatever power-sources
>> I decide to put on it.
>>
>> Check out http://www.barebonespcb.com
>
> Thanks, David. I use gEDA and have fab houses build the
> boards, but I've been so into the whole breadboard it all
> up first concept that I hadn't really thought how cost
> effective it would be to hybrid breadboard/circuit fab.
> What a great idea.
Its so much nicer to have a bunch of little PCBs with
serial translators with DB9s and headers etc lying around
than it is to have veroboard monstrocities :)
Cheers,
Dave
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