I designed a PCB. What''s wrong with it?
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Posts: 46,084
Referenced documents:
http://members.cox.net/jmccorm/pcb.jpg
http://pdfserv.maxim-ic.com/en/ds/MAX6956.pdf
http://www.superbrightleds.com/TriColor%20LED.htm
> Please don't think I'm being harsh, and these are my opinions, not
> some industry standards.
Are you KIDDING? I thought your feedback was great! (In fact,
invaluable since I've never created a board to be etched before.) A
few questions though...
>> R-1 is located so as to force pins 4,5,6 and 7 to angle on exit.
R-1 only needs to be 1/4 watt or even 1/8 watt so the traces are much
larger than required. <<
I thought that R1 would be in the neighborhood of 2 watts, as it
serves as the global current limiter for all of the LEDs (20ma * 18
segments * 5v=1.8 watts), so I was being generous with the traces. Of
course, I make the assumption that it has to be able to handle all the
current going through the LEDs. I don't know if I'm wrong or not! I am
far better of a programmer than an electrician! I'm hoping I didn't
screw that up.
Since I have the room, maybe I should at least make R1 horizontal
insteal of veritcally oriented.
In general terms, I tried to scale the trace widths to the current
flowing through it. Signals given the smallest traces. Major +5 and
GND feeds given the largest.
>> Also, since you have 3 resistors for each LED, I would group the
resistors in lots of 3. Running them around the mounting hole is no
biggie, but for troubleshooting it is much easier if the layout is of
components aligns with the devices they serve. <<
I thought about that. With my limited knowledge, I figured that the
bigger problem would be drilling the holes. So I kept as many as
possible in a straight line to make that part easier. With my intent
in mind, was that a good decision or a bad one?
>> The only real caution I offer is that the key be moved a little bit
off the close proximity of the DIP. <<
Very good point. Thanks!
>> I have been making boards for people (mechanically etched
aka-routed) and I concern myself with the details. <<
I think I'll hit you up when I'm ready!
http://members.cox.net/jmccorm/pcb.jpg
http://pdfserv.maxim-ic.com/en/ds/MAX6956.pdf
http://www.superbrightleds.com/TriColor%20LED.htm
> Please don't think I'm being harsh, and these are my opinions, not
> some industry standards.
Are you KIDDING? I thought your feedback was great! (In fact,
invaluable since I've never created a board to be etched before.) A
few questions though...
>> R-1 is located so as to force pins 4,5,6 and 7 to angle on exit.
R-1 only needs to be 1/4 watt or even 1/8 watt so the traces are much
larger than required. <<
I thought that R1 would be in the neighborhood of 2 watts, as it
serves as the global current limiter for all of the LEDs (20ma * 18
segments * 5v=1.8 watts), so I was being generous with the traces. Of
course, I make the assumption that it has to be able to handle all the
current going through the LEDs. I don't know if I'm wrong or not! I am
far better of a programmer than an electrician! I'm hoping I didn't
screw that up.
Since I have the room, maybe I should at least make R1 horizontal
insteal of veritcally oriented.
In general terms, I tried to scale the trace widths to the current
flowing through it. Signals given the smallest traces. Major +5 and
GND feeds given the largest.
>> Also, since you have 3 resistors for each LED, I would group the
resistors in lots of 3. Running them around the mounting hole is no
biggie, but for troubleshooting it is much easier if the layout is of
components aligns with the devices they serve. <<
I thought about that. With my limited knowledge, I figured that the
bigger problem would be drilling the holes. So I kept as many as
possible in a straight line to make that part easier. With my intent
in mind, was that a good decision or a bad one?
>> The only real caution I offer is that the key be moved a little bit
off the close proximity of the DIP. <<
Very good point. Thanks!
>> I have been making boards for people (mechanically etched
aka-routed) and I concern myself with the details. <<
I think I'll hit you up when I'm ready!