Robert Hedan wrote:
> I'm interested.
>
> Let me know what kind of money you want once you've got a detailed breakdown
> of your parts and outsourcing.
>
> I suppose PayPal would be an acceptable payment method?
>
> I have my own DIP 16F877s on hand, as well as plenty thru-hole resistors and
> capacitors. I don't know if you're going all SMD to cut down on spacing,
> but maybe you can offer a kit where we can add ordinary parts. You could
> include those design-specific parts like the MOSFETs and such, just an idea.
>
> Robert
> :)
>
>
Well I need to get it laid back out and back before worrying about details
too much. But yeah PayPal would work since I'm on Ebay etc.
The FETs I have 2K on hand. The 7406s I have 500. Resistors the same. For
what the number would be it'd hardly make sense to leave them out, consider any
you already had on hand as spare parts.
The 7406s are DIP, so fairly locked in. The PIC is the one thing that really
saves space using a SMT part. Easy enough to sample a few from Microchip if you
don't have any. I have some on hand as well.
With two copies of the board, I may toss the 5th set of FETs on one board and
squeeze it to just to 4 phase. That would likely let the DIP back in if it
won't squeeze in with 5 phase.
Note there are a few other things to do before I send it off. The PSP port
uses up a lot of pins on the PIC, so many it can't run all 5 phases. That's
what one 595 was for, the other for an LCD.
I plan to scrap the PSP for reading the parallel and switch to serial. Able
to do real serial for USB-serial adapter use, or able to use the inverse of the
595 to read the parallel port pins in a serial manner. This will let it use the
same pins to talk to USB or 232 serial, or the parallel port either intelligent
or just read pin states, all through the same few pins and only jumper a few
things etc. More options with the same few pins, and the PSP pins left to
either run the 5th phase gates or talk to an LCD without an extra part.
Also consider the original board did have reverse diodes on the FETs. Only
problems I had were blowing gates, once I figured out why and did the right
things to eliminate it I had almost zero problems. Only a few FETs blown after
that, from shorting things testing and rough handling. Took the diodes off one
set to see and never had any problems attributed to that. If there is room left
over, it only takes a tiny bit of spreading to put the holes back in. Then just
mount the FETs on top, solder them in, and put the diodes in on bottom. But
there is an inherent diode in the FET and it's a 13A FET, don't think you need
them much with 5 or 7 V 1A motors. I never had many failures with it when
running even before I fixed the problem on gate blowing. Problems all came from
screwing around with it in odd ways. Even the gate blowing only really happened
when I was plugging in motors while it had running patterns going on. Fixing
the drive method stopped that. But again, easy to put them in if there's room,
easy enough to solder them in place to the transistor leads on bottom even if
there's not room for holes too.
There is a lot of stuff to get done before I can even send it off, made worse
by so many different boards going on it. None of it is that hard, but it will
likely be a week before it gets out now.
Alan