Bloody pinouts!!

[Mark Hammer]

I'm trying to finish up a 12-fuzz rack unit for myself, and one of the included circuits is a triangle (or Ram's head, I forget which) Big Muff, using little "button" type 2N5133 transistors (well, 3 of them; I used a BC546b for the output stage).  I thought I had identified the pinouts correctly before installation, but apparently I was mistaken.

Everything on the circuit was working as man and nature and Mike Matthews intended, but the level was appallingly low, and the max gain was VERY modest with little clipping.  Going through it last night, I realized the damn transistors were installed backwards.  I stuck a 546 in the hfe-testing socket of my meter and realized that one was backwards (E and C flipped around).  I had one remaining 5133, and realized that one was also likely opposite to what I thought.  Had I used sockets, this exercise would have been less painful, but unfortunately everything was perfed, and in rather cramped fashion too, to conserve space.

So, last night I began unsoldering parts, flipping things around, and reperfing.  I've got 3 of 4 done, with each flip resulting in more level and distortion.  Number four comes tonight.  Then I can put the damn thing to rest.

To borrow a well-worn adage I should have observed: check pinouts twice, build once!

[duck_arse]

I've always thought the 2n series had the pinout backwards/wrong, and the bc series was right.

[Mark Hammer]

The trouble is that I think neither of them have anything consistently.

Personally, I tend to remember the pinouts (and I use the term "remember" in a qualified fashion!  ) using a combination of both the way schematics are drawn (V+ at "top", ground "below"), and a mental image of the transistor.  So, a TO-02 package might be remembered as "facing where the signal is coming from", or "facing where its sending the signal".  Putting those notions, and the schematic-influenced idea together, an E-B-C pinout would have the flat side (where the part number is generally shown) "facing" towards where the signal is going next, and a C-B-E pinout would have the transistor "looking at" the input signal.

The button types, having no discernible "face" (though I realize some have a slightly flattened arc) on which the part number is printed, have their pins staggered into a triangular pattern.  There, I mentally approach it like a little Pac-Man that is either catching and eating the electrons coming its way, or spitting them out.  That is, assuming a pinout with the emitter and collector separated by the largest distance, the base is either closer to, or farther away from, the input to that base.

Would I recommend this as a suitable way to remember?  Well, consider that I use it and I started this thread in utter frutsration.  Not much of a recommendation, in retrospect, but then whatever works for you, eh?

[R.G.]

I posted this recently, but I think it's pertinent here.

I have come to believe that all semiconductors in fact have no hard-wired external pinout, and that Maxwell's Demon, who lives in all electronics devices, randomly changes the pin functions at odd times.

Maxwell's Demon is repelled by datasheets, much like vampires from garlic and mirrors, and so the only sure way to fix the pinout of the devices I have in my hand to keep them from changing on the way to the board is to lay the board being soldered **on the printed datasheet**.

It's all I could come up with, anyway.

Maybe I need to have my soldering iron blessed, or silver plated, or something.

[midwayfair]

I had a very short phase where I decided not to socket anything if I could help it. No longer. Not even when I have photographic evidence of the orientation of the exact same transistor types from the exact same batch in the exact same circuit.

RG's gotta be onto something. Damn imps.

[Mark Hammer]

I posted this recently, but I think it's pertinent here.

I have come to believe that all semiconductors in fact have no hard-wired external pinout, and that Maxwell's Demon, who lives in all electronics devices, randomly changes the pin functions at odd times.

Maxwell's Demon is repelled by datasheets, much like vampires from garlic and mirrors, and so the only sure way to fix the pinout of the devices I have in my hand to keep them from changing on the way to the board is to lay the board being soldered **on the printed datasheet**.

It's all I could come up with, anyway.

Maybe I need to have my soldering iron blessed, or silver plated, or something.

Or maybe it's just a reason to simply do EVERYTHING with 2N5088s, and disregard whether the schematic calls for silicon or germanium, NPN or PNP, small signal or power, bipolar or MOSFET! 

[Perrow]

What's that thingamagick "something 55" that tests (almost) any two or three pin device and tells you device type, pinout and vital statistics? It would definitely be a bliss to have on the bench.

Googling pinouts on the smartphone is my preffered solution pending purchase of said piece of tecno-magic.

[R.G.]

What's that thingamagick "something 55" that tests (almost) any two or three pin device and tells you device type, pinout and vital statistics? It would definitely be a bliss to have on the bench.

That would be great - except that my experience is that even if you check the pinouts on a piece of equipment, Maxwell's Demon changes them between the tester and the PCB unless you have the PCB sitting on a printed copy of the datasheet.     

Long ago I transferred my practice of ordering parts in 100's where it was economically feasible and keeping a supply of parts that built up incrementally as I needed them over to caching datasheets. When I use a new/different part, I download the datasheet, and stuff it in a folder of datasheets in the hard drive. This is subdivided into resistors, caps, transistors, switches, etc., and I've found that this saves me a lot of time later.

[chptunes]

Great posts above.. I've learned quickly that sockets are my friend.

-Corey

[R.G.]

I used to do sockets on everything.

Then I found that there are malicious sprites living in the air everywhere that sneak into socket holes and eat up the contact metals a little at a time. After a while, the socket pins go intermittent, scratchy or simply open.

After a while I noticed that sockets are often more expensive than the parts I was putting in them, and I just decided to learn to solder and de-solder better so I could go cheap and not use sockets, frustrating the air-sprites by sealing them out of the contacts with a layer of melted, then frozen tin-lead. This, combined with the exorcism of Maxwell's Demon by the laying-on of datasheets seems to work pretty well.

Well, that and the garlic garlands.

[Mark Hammer]

I suppose the other consideration is that any socket, machined or otherwise, has to grip the part firmly enough that it will remain in place despite being stomped on, and hurled about in the back of the van, or on the loading dock.

One approach is to tin the transistor leads and give them a little extra girth to fit more snugly.  Another is to make use of stuff like Stabilant to bridge the socket-to-pin gap with conductive fluid and keep the demons out (I've successfully resurrected stuff that was misbehaving by applying little droplets of it to socket pins).

A third strategy might be to leave a little space around the socket, and once you've reached closure about transistor choice or orientation, solder the thing into the socket if you can.

But yeah, sockets are helpful...just not magical.

[petey twofinger]

maxwells demon makes regular appearances at my home , forgetting to flush the toilet , leaving the door open (gee its chilly in here) feeding the cat shrmipy treats which produce a pungent gas .

will handrawn pinouts work just as well ?

i really hate wasting toner .

[Perrow]

I'll start sorting my transistors by pinout

[Kesh]

The one single thing a DMM hfe tester is good for is confirming transistor pinouts.

[Tony Forestiere]

[pinkjimiphoton]

LOLOLOLOLOLOLOLOLOLOL!!!!!

i ALWAYs socket now.

even then, sometimes it doesn't seem to matter which way the dang transistor is flipped...

sometimes, it's just a guess.

[duck_arse]

is "maxwell's silver hammer" (no pun intended) a corollary of "maxwell's demon"?

I just flat down, with pins pointing at me, e-b-c. if 2n series, it's backwards, and keep yr finger on the e as you turn it over/around, or it moves. works for buttons, tags and dots. also fets, but then its 2n = g - s - d, and bf is backwards.

teach that to the kids, easy!