JuneBug - BS250 orientation

[LabRat]

Greetings to everyone on the list.

I've been lurking for a bit, and last week ordered a JuneBug kit. It was waiting for me when I got home yesterday after work, and come 2:00 am I was scratching my head over which way around the BS250 should be installed. It's not the sort of part that I would want to try and de-solder, if I get it wrong.

The Device: BS250KL

What I have done: Googled the part, went to the VISHAY site, and perused the datasheet. To the best of *my* abilities (as a software guy we're pushing the envelope here), I believe that part shoud be oriented 180 degrees from the symbol on the board.

(BTW: Thanks for the heads up in the build sheet, about checking this pinout)

Can anyone else confirm this before I commit to soldering the part?

Thanks for any help/pointers.

 

[blueroomelectronics]

I'll have to update the Junebug manual, it goes in same way the 2N7000 & Q1 do.
Both the 2N7000 & BS250KL go flat side facing to the right of the PCB (ICD connector)

 

[LabRat]

Geez Louise that was a quick turn around time!!

Thanks that is exactly what I had thought. (Phew)

If you are updating the manual I seem to recall the following:
a. You listed install R4 through R16 - never mentioned R17
b. For the 3 colour led's on the "programmer" you had them listed as LED5 6 & 7, should be 7,8 and 9

Thanks again.. looking forward to finishing this off!

 

[blueroomelectronics]

Glad to help, make sure you search the forums here for Junebug. Lots of hints and even some tutorial by members here.
Attached is a really rough draft of the upcoming Junebug assembly manual. Mostly the EEPROM table & 24FJ16GA002 connections.

 

[AtomSoft]

Nice additions especially the 18F1320 Instruction Set

 

[blueroomelectronics]

Nice additions especially the 18F1320 Instruction Set

The instruction set is very incomplete and somewhat wrong, it's a paste from the 16F88 document in the Firefly manual.

I'll fix it of course.

 

[LabRat]

Lessons to be learned: No more soldering past 1:30 am.

Looks like I might have an incorrect Transistor as part of my Junebug package.
3904 x3
2N7000 x1
BS250 x1

Missing 3906 - what I received (and didn't notice) was KN2222A
But 3906 = PNP whereas KN2222A = NPN

Which I didn't notice until just now

Suppose this might explain why I can't detect my the 18F1320??

Time to scrounge around what I've kicking around here.

 

[blueroomelectronics]

Darn, I can ship one to you sorry about that. but any general purpose PNP should work with the same pinout.

 

[futz]

I'll have to update the Junebug manual, it goes in same way the 2N7000 & Q1 do.
Both the 2N7000 & BS250KL go flat side facing to the right of the PCB (ICD connector)

Oh, that could be bad. Mine might be backwards. What bad things can happen? Junebug still works anyway.

 

[blueroomelectronics]

If the BS250 is backwards its diode conducts an it'll always supply power to the target, no damage though. The PNP enables VPP, you do need that one.

 

[futz]

If the BS250 is backwards its diode conducts an it'll always supply power to the target, no damage though. The PNP enables VPP, you do need that one.

Target power switches on and off normally. I referred to a datasheet. Have no idea if it was the right one, but if it works I'm ok, I guess.

 

[LabRat]

<sound of rummaging> MPSA18.. 2N5401... 2N5087... 2N4400... AH HAH 2N3904.. (oh wait.. dang.. wrong one)

What have we here... 2N4403?? Which according to Hey hey.. seems a likely fit!!
Referencing: **broken link removed**

Bill thanks for the offer to send a new one, but I think this one will work. No?

 

[LabRat]

Bill,

Thanks for the offer. But if I'm not mistaken a 2N4403 that I scrounged up should do the trick. No? (sorry if this echoes an early POST, but it seems my previous "quick" response vanished into the ether).

 

[blueroomelectronics]

The 2N4403 is a fine choice. Sorry about the mixup.

 

[Funny NYPD]

can anyone post a picture of BS250? I don't quite understand how its pins get mis-placed?

Most of the time chip vendor will put a clear mark to identify the pins.

Or the chip could never go wrong because of the special made shape. something like a SOT23 package, it would be very hard to go wrong since there is only one pin on one side and two pins on the other side.

So far, I have never hear anything like this happed on the DIY kits we designed, even for the most popular CB0703 (PICkit2 DIY) board.

 

[blueroomelectronics]

The BS250K is a through hole TO-92 and like many FETs has a integrated diode across D&S. You're right a SOT23 only goes on one way.

 

[LabRat]

To understand what happend just compare these two data sheets:
https://www.zetex.com/3.0/pdf/BS250P.pdf
and
https://www.vishay.com/docs/72712/72712.pdf

You will see that the two parts appear to have reverse pinouts. So as Bill points out in his "Assembly Manual", we should always check the pinout for the part during assembly. (Something I SHOULD have done with the 2N2222 part (silly me))

 

[blueroomelectronics]

Silly me for including it
Does your Junebug see the 18F1320?

 

[LabRat]

I haven't been able to replace the transistor yet (as you recall I promised myself no more "wee hours" soldering ). I'm hoping to cut lunch short, and use the lab downstairs at the office to find time to replace the part.

As of right now.. "NO" it doesn't see the device (reads back 0x00 for the device ID).

 

[Funny NYPD]

To understand what happend just compare these two data sheets:
https://www.zetex.com/3.0/pdf/BS250P.pdf
and
https://www.vishay.com/docs/72712/72712.pdf

You will see that the two parts appear to have reverse pinouts. So as Bill points out in his "Assembly Manual", we should always check the pinout for the part during assembly. (Something I SHOULD have done with the 2N2222 part (silly me))

Please don't feel sad. Things always happen. But once we learned the lesson the first time, we know how to make it not happen again.
Thanks for the kindly reply, It cleared my confuse.