Author Topic: PNP base resistor  (Read 9726 times)

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Offline hamdi.tn

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Re: PNP base resistor
« Reply #25 on: December 17, 2014, 05:46:34 pm »
been there myself, just try to rotate it so the right pin meet the right pad and solder it that way, i did that, but i didn't have that much transistor to remove and solder again.
 

Offline Falcon69

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Re: PNP base resistor
« Reply #26 on: December 17, 2014, 05:51:01 pm »
cn you bend the pins, and flip the chip upside down maybe? Hand solder them?
 

Offline hamdi.tn

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Re: PNP base resistor
« Reply #27 on: December 17, 2014, 06:02:10 pm »
i think what you will have to do is to rotate the package 120° trigonometric direction so pin 1 take 2 pin 2 take 3  and pin 3 fixed to 1
 

Offline mij59

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Re: PNP base resistor
« Reply #28 on: December 17, 2014, 06:36:50 pm »
Came home, checked it out. Yup, wrong footprint. I am on the edge of crying like a little child.
What are my options now? In my footprint, I have collector on pin 1, base on 2 and emitter on 3, are there any PNP BJTs with
this footprint? Should I just remove the BJTs and hope that the 74HC595s can handle the current?
Or should I just frame the board, put it on my wall to remind me why I have triple check the footprints?
Thanks all! You've been an enormous help!

Don't cry over the board use a handkerchief.
Replace the transistors with TO92 footprint transistors  and use the board to do further testing.
The 74HC595 can't handle the current .
 

Offline dandeTopic starter

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Re: PNP base resistor
« Reply #29 on: December 17, 2014, 06:43:20 pm »
Don't cry over the board use a handkerchief.
Replace the transistors with TO92 footprint transistors  and use the board to do further testing.
The 74HC595 can't handle the current .

:))
well, at least the MCU part with the power supply is working correctly with the programmer part. I just need to be happy
with what went good on the first try. It should have been a christmas present, and because I have to work, I won't have time to
source the needed parts. Also, I am not sure that the 74HC595s are working correctly, but I'll test that it later.
I now need a nice little frame with the title "F*cktard! Check the footprints!!" Any ideas? :D
I am programmer with a soldering iron. Run!!
 

Offline KJDS

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Re: PNP base resistor
« Reply #30 on: December 17, 2014, 08:30:17 pm »
It's easy enough to fit a transistor with the legs swapped. I've done it more often than I care to remember.

Next time, go through each part you want to use in the layout and check the footprint and pin out. Rename it to "78L05 checked" or move it into a directory named checked.

Offline dandeTopic starter

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Re: PNP base resistor
« Reply #31 on: December 17, 2014, 08:33:05 pm »
It's easy enough to fit a transistor with the legs swapped. I've done it more often than I care to remember.

Next time, go through each part you want to use in the layout and check the footprint and pin out. Rename it to "78L05 checked" or move it into a directory named checked.

Thank you! It is great advice!
To be honest, I don't want to "hack" the board, one of the idea behind it was it's "niceness", as I said it was meant
to be a gift, but I got a couple of fallbacks, since I've learned already, that "Murphy always gets you" :)
I am programmer with a soldering iron. Run!!
 

Offline KJDS

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Re: PNP base resistor
« Reply #32 on: December 17, 2014, 09:11:03 pm »
It's well worthwhile building up enough transistors fitted "wrongly" to show that it works. Otherwise you'd relay out the board, get it made and discover another silly fault that would have been easily fixed if you'd done a little more testing on the first version.

I've made some horrible horrible mods on first iteration layouts, but doing so meant that the second version worked properly.

Offline dannyf

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Re: PNP base resistor
« Reply #33 on: December 17, 2014, 09:27:33 pm »
You can swap C/E pins and they will continue to function as a switch, with low beta.
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