EQD Hummingbird

[Themilksteak]

Hey guys, this is my third build of this layout and I just can't get it working.  I've tried every pinout I could find for the 2n2646.  Some seem to be different from others but I tried  them all and all I am getting out of this thing is the regular signal.  Can anyone throw their two cents in here?  Cause I'm stumped and would rather not trash it.  Thanks in advance fellas.

[Themilksteak]

Sorry here's the layout.

[tabbycat]

hey the milksteak, welcome to gfx and congrats on your build.

i have the vox repeater, which is kind of the same thing. you definitely need that to work.

i have given your build a browse and it appears (could be a trick of the light) that the 12k resistor that is supposed to connect to the source (middle pin) of q3 (2n5457 jfet) is missing the hole.

worth double checking.

also the soldering looks pretty neat but always worth running a stanley knife (or whatever you call a small blade where you are) between the copper strips in case any solder has strayed into the gutter and is making a connection between the strips it shouldn't.

try those things and get back.

[rocket88]

just took a look at it, and that's the one thing i saw. the 12k resistor next to Q3, should go from the source to ground. the way you have it, it's connected at the ground, but 1 row low on Q3, so it's connected to the gate.

[Beaker]

This is the pinout for a 2N2646:





Fix the error that Tabbycat and Zach has identified, then try again. If it still does not work, then you need to consider the following:-

If you have tried to solder the same 2N2646 in several orientations (and therefore several times), you have probably unfortunately toasted it.

It's far better to use sockets for this, as 2N2646 are flakey critters to say the least - some will work fine, some sort-of work, and some just won't work at all.

If you have spare 2N2646 UJTs, use a socket strip, and then mount your UJT into the sockets.
That way, you can find out if they are working.

Also, did you test this circuit before you boxed it? if you did, and it worked, check all your offboard wiring for errors.

This is one circuit I would never attempt to box, without thoroughly testing it on my test unit first.

Hope this helps.

[Themilksteak]

Thanks guys.  I tried the exacto/Stanley knife this morning.  And tried changing the pinout again(I actually did use sockets for the 2646 since beaker informed me how inconsistent they are.  Here's another view of that 12k resistor (which is a 15k cause that's what I had lying around). I hope that doesn't affect the problem.  Here's another image

The problem I see with my 2646's is when I look at a pinout the nub on the top of the cap doesn't sit where the pinout says it should.  If that makes sense.  I was using the sockets and the 2646 was a little loose in them but I was just hoping to find the right way around and then perhaps solder it.  Unfortunately I didn't test it before I boxed it I'm waiting on one more piece to finish my beavis.  I guess I should just give up.  Although one question.  The metal from the sides of the pots and the side of the switch touch cause I placed them to close.  I figured that didn't matter.  Could that be a problem?  Is that stupid question ?  I've built a bunch with no problems so I don't know the deal here.  Maybe some faulty eBay transistor I just wanted to build this before I got to building a bit commander to work my way into the more difficult stuff.

[Themilksteak]

* beavis board.  Sorry my phone likes messing with me.

[Beaker]

What are the markings on your 2N2646? Please post up what markings are printed on them.

I have some GE and Motorola ones - if it is one of these brands I should be able to help confirm the pinout.

As for the pot bodies touching the switch, it should not matter, but try sliding a piece of electrical insulating tape between them just to make sure. Either that, or temporarily remove the rate switch from the enclosure (but keep it wired up). It is possible that they are pressing a liitle too hard on each other, which has caused the pots or the switch to break or malfunction. This has happened to me once!

[Themilksteak]

I got 'em on ebay.  It says generic/unbranded.  So I guess I have to get the motorola/or name brand ones?  I'll do some searching too.  Thanks for all the help fellas.

[Chris60601]

With the Bay, you get what ya pay for. Yes I know, there are reputable folks that sell on eBay, but you always run that risk.

I would much rather pay a little bit more from a vendor that is not on eBay and feel reasonably sure that i am getting what I am supposed to get.

Like most everyone else, I work hard for my money and don't want the added stress of wondering if I'm getting a good product from eBay.

Of course, your mileage may vary as I am speaking from my own experiences with eBay.

That being said, you can imagine that I prefer to NOT do eBay business

[Beaker]

I hate to say it, but they look well dodgy.

I've just had a quick look on ebay, and found one of your photos in a listing. Did you get them from this seller in China?

http://www.ebay.co.uk/itm/10-pcs-2N2646-Manu-ON-Encapsulation-CAN-3-Silicon-PN-Unijunction-Transistor-/161750415693?hash=item25a913794d

If you did, they are almost certainly fakes. I bought some J201 JFETs from them a while ago, and they were fakes too. This seller needs putting on a blacklist.

There are quite a few on ebay at the moment, but buy them only from a reputable seller, and look for well marked (as in well printed), known names llike Motorola, Harris, Multicomp, GE, Texas Instruments etc.

[Themilksteak]

Argh, Mine came from here http://www.ebay.com/itm/391188141231?_trksid=p2060353.m2749.l2648&ssPageName=STRK%3AMEBIDX%3AIT

but essentially they look like the same exact profile just for different countries to ship to.  The watermark and all is identical just different profiles.  I'll give them all a shot when I get home and hope at least one works  in the interim I'll order up some from small bear.  I'll let you know if any of em work at all.  That sucks man I was only ordering from them cause I wanted multiples for spares/extra builds and that was a ten pack.  The signal goes through em and all just no effect.  Oh well.  Thanks again

[Beaker]

No worries, just sorry to be the bearer of bad news.

Like I said earlier, even the top quality ones are flakey, so these are are probably garbage.

[rocket88]

Just to add to what beaker said about then being fake and chinese sellers. You've got to be careful with some of them, especially with ICs. I try to avoid buying rare parts from china, since there seems to be a lot more fakes coming out now. For me I've had good luck with common still in production parts, as there's not much return on rebranding them. Also, remember of you see something for a price too good to be true, it is. So if the low end of 50 TL072 ICs are going for around $8, and you see someone selling them for $3 avoid it. There are a lot of bad/untrustworthy sellers from china that have multiple names on eBay, but it's all really coming from the same main company. It's actually part of the reason for the creation of eBay protection.

[Beaker]

Agreed.

I've used this seller a few times before, buying common and in production parts, without any problems at all. Then I bought the fake J201s from them, which has put me off ever ordering anything from them again.

I think that just about anything from China is ok, as long as they are easily available elsewhere, and relatively cheap. If parts are cheap and easy to get, it really is not worth anyones time faking them.

As soon as parts get rare and therefore expensive, then the fakers see an opportunity to make money.

I'm not the only one to get stung, but now if I need something exotic, I'm really careful about who I buy from.

[Themilksteak]

I pciked these guys up.  Let's hope that works.  I'm gonna check the other ones when I get home with a multimeter to see what's up.

http://www.ebay.com/itm/141701824002?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 Thanks for all the links and good info.  I appreciate it!

[rocket88]

I've bought from him before, and had no issues. Let's hope that same goes for these.

[Beaker]

Gold leads - always a good sign.

[Themilksteak]

Thanks for all the help guys!  Got the parts and everything works great.  It was also shorting out with the pot touching the casing due to my terrible layout. I put a dust cover on the pot and everything works great!  I appreciate it!

[Beaker]

Glad you got it sorted, and everything is working.

I recomend that you now either solder the UJT into the socket, or remove the socket and solder it to the board.
If it works even slightly loose in the socket, it will start ticking loudly, or the effect will go "weak" sounding.

Also make sure the UJT has some clear air all around it.
If it touches another component, or the base pate of the pedal it will tick really loudly, as they are really microphonic - try pinching the body of the UJT between your finger and thumb while the effect is switched on, and you will hear what I mean!

I've had to make little foam collars on a couple of mine to help keep them safe and cozy!