Donald,
? Of course doing it right the first time is the plan. I was just asking noob like questions just in case there was a use for that. I used to (and still do a little) program software and I have loads of REM statements so I don't forget what I did. But working with a team of developers or for a company that makes software is where it is even more important. I have formulas in my notes explaining what I used and why math in the software was done as it was. etc. But nobody is ever likely to see my code except the hackers. :) Now back to my pcb... I use red for positive and black for negative and have and will continue to have the info on my pcbs when they are made. The first one (the only one) that I have had made has the + and - a little small, but its there. I like the JST connectors as they are keyed and that is why I bought them. So with what I have learned is useful for other uses of the jumpers and non-keyed stuff. Lets say instead of a variable resistor I could have different brightness of some led's if the jumpers were switched to a different resistor or set of resistors.
Thanks,
Dave
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On 11/14/2020 2:15 PM, Donald H Locker wrote:
I would still strongly recommend a polarised connector. Somewhere down
the road, someone (it might even be you) will have to look at your PCB;
you wouldn't want them to think, "What was he thinking?" Make it easy
for that person.
I spent most of my life doing programming, rather than
electrical/electronic stuff, though I did plenty of that too, and
encouraged my programmers to remember: you aren't writing code for the
CPU, or the compiler; you are writing code for some poor SOB three years
after you've gone away, who has to figure out why you did what you did.
Any half-decent programmer can read the code and know what it does; what
they need to know is WHY it does what it does! Make it easy for them.
My opinion,
Donald.
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On 2020-11-14 1:18 p.m., Dave wrote:
Harvey,
? In my case the circuit is so simple no harm can be done but I do get
your point. From the batteries to a jack with a female plug. Inside the
box the jack is hardwired to the pcb. The only time it has to be swapped
is on assembly and is covered after that. What got me in the beginning
is that the IR led's I use have the anode and cathode reversed so the
flat on the LED is not the cathode or the negative like 99% of the other
led's out there. I always test them on the breadboard but being my mind
always thinks the negative is the short lead, I have solder the red and
black wires onto the led incorrectly. Then as assembly continues it ends
up backwards. It is not a big deal though as now I have ordered some
Dupont female pins and housings to solve that issue if it ever comes up
again. For the most part I likely won't ever make the mistake again but
was curious if a polarity switcher was possible a device because they
seem to make everything.
Thanks,
Dave
On 11/14/2020 11:59 AM, Harvey White wrote:
I would not use reversing a connector for the fix of an LED installed
backwards.? I'd be very tempted to check them first. Most of what I
use has an index mark on it indicating the cathode.
If you have a board where you can plug in the power backwards, then
you have to think about how to plug in the power every time. Thinking
is a quantity noticeably absent as the hour for late night debugging
goes past 12 midnight.
One group of college students was in a robot competition, powering
their project with a high power lithium ion battery. They didn't key
the connector (for whatever reason), nor did they install any sort of
polarity protection, not even a fuse and a reverse biased diode.
Three hours from home on a Sunday and before the competition, they
plugged in the battery backwards and blew every power module in the
robot.? Even an early morning run for spare parts made no difference
to the outcome.
And that is why George always wear hat when visiting Tooki-Tooki bird
friends.
One of the tweezer probes with banana plugs and one of the parts
checkers (transistor/diode/LED/capacitor) can be used to identify an
LED before you put it in.? Since they run off 5 volts (regulated from
a 9 volt battery), you have enough voltage for blue and white LEDS.
You can also get them with a PC board pattern that allows directly
putting SMT chips on the tester.
Harvey
