First pedal, need confirmation

[primedynasty]

Click for enlarged picture

So like the title says, this is my first attempt at making a pedal.  I want to making something I could use, and being a bass player, I need a fuzz pedal.  I have all my parts already, but I just want to make sure I am interrupting the schematic properly.  I got a little confused about hooking up the stereo jack with the LED.  Is everything on the right terminal?  Also do you hook up the third terminal on the DC power jack to ground?  Does orientation on the transistor matter?

Also, I want to verify, the side of the axial electrolytic with the indent is the positive side, correct?  I appreciate any and all help.

[Mark Hammer]

1) I'm looking for the transformer, but I'm not seeing it.  Are you omitting it?

2) You've got a rat's nest of wiring there, a lot of it unnecessary and likely to increase mixups and confusion.  Pick a useful spot on the board and run ground to it.  Ground from the pots, ground from the jacks, ground from the LED.  You'll use less wire and you'll be able to see things.

3) With a 100k current limiting resistor, you either have one helluva bright LED, night vision goggles, use the pedal only within absolutely light-tight rooms where that LED is the only available source of photons, or else you have no serious desire to know whether the pedal is on or off.     For the vast majority of commercially available LEDs, even the superbright ones, you'll want to stay well below 22k.  Garden variety LEDs like you find on Boss pedals, will want something less than 4k7 in order to be visible.

4)  Many pedal-makers will secure the LED to the board itself, with the legs/leads left fairly long and some insulation (heat shrink or simply stripped wire insulation) around the LED leads.  Pop a hole in the chassis and line up the LED with the hole when you install it.  This way, you can simply run a pair of wires to the stompswitch for actuating the LED or cancelling it, without having a bunch of "flying" components hanging off the switch.

[primedynasty]

1) Yes, I am omitting the transformer.  I have one, but I didn't really understand how to hook it up and I play a passive bass, so I took the lazy way out there.

2) I totally agree, and I was really trying to get everything in its right place, but it does need some editing and the led won't be where it is, that was just to make sure it was in there.

3) I mislabeled that one.  I think I meant 1K which I got from the beginner project, is that too low?

4) that is a great idea, thanks.

What about the transistor orientation or the wiring for the dc power jack, just want to make sure I have those right.  Also, need to make sure i have the electrolytic going the right way as I have read it could go out in quite a dramatic fashion if i don't.  I am under the impression that the indented end is the positive terminal, is that right?

Thanks again for the response, I appreciate it.

[jacobyjd]

i use 1k for all my LEDs--that should work just fine. 

[Mark Hammer]

Yeah, 1k is generally fine.  Depending on the LED it may provide more brightness than you really need (which amounts to wasting battery current for no good purpose), but it won't harm the LED.  You may find that 2k2 is a useful value as well.  Judge whether you need the LED as bright as it is (or brighter) and adjust resistance as necessary.  Most lower-brightness LEDs will want 1k or thereabouts.  Others will be visible enough with a 2k2 or even 3k3, depending on the LED colour and background (red LEDs against a dark background need less brightness to be seen).  If you use a "superbright" (3000mcd or higher), you can even get away with 12-15k and still see that sucker easily.  For minimizing current consumption, you'll want the lowest brightness (hence highest series resistance) you can get away with.

[primedynasty]

ok, sweet.  So everything looks good, I am ok to start wiring this thing.  I am super excited to get started.  I just rewired my entire bass and it was super rewarding, thought a little nerveracking when I first fired it up, but I am excited.

[asfastasdark]

To answer your question: Transistor orientation definitely matters. Look up a datasheet for your transistor to find which pin is which (unless you already have this), and put the right lead in the right place. I'd also recommend using a socket for transistors because you can kill them easily while soldering, and afterwards you can play around with other transistors.

[asfastasdark]

Here, I made a better layout for you in case you wanted one. Now you can use only 10% of the perfboard instead of the massive amount you were first using .

Pay close attention though, it may be hard to see the jumpers underneath.

[jayp5150]

It looks like you had your transistor flipped (depending on pinout... have to double check).

Also, you have the input going to the emitter, and the base and collector tied together under the tranny.

The post right above mine is how it should look.

[asfastasdark]

The post right above mine is how it should look.

Yay! 

[primedynasty]

wow thank you so much, I really appreciate the revised layout and it is good to know that I had it wired completely wrong. 

[primedynasty]

Ok I got the pedal built and it is fantastic.  Has a really great sound.  I definitely made a lot mistakes but learned a lot as well.  The only thing that I still don't understand is how to hook up both the battery and the DC power jack.  I have the jack working right now, but it is not being managed by the ring of the input jack, it is just on when it is plugged in.  If I unplug it, the battery doesn't do anything.

So what is the proper way to hook this up?  Anyone have a diagram that could help?

[Mark Hammer]

The principle underlying battery jacks is that a default physical connection is made when nothing is inserted into the jack, and that connection is disrupted and displaced when something is inserted into the jack.  When the jack itself is large and open, it is easy to see what is getting bumped out of the way upon plug insertion, and almost equally easy to see what solder lugs everything connects to.  When it's tiny barrel-style jacks, or mini phone jacks, the visibility and obviousness of the connections is less clear.  This is certainly compounded by different manufacturers adopting different configurations to do the ame thing.  The lug where the battery needs to be connected to might be the middle one on this brand and the outside one on that brand.

So what do you need to look for?  You are looking for two of the three solder lugs that have continuity when nothing is inserted in the jack, and no continuity when the plug goes in.  If you have a continuity tester, or beeper on your meter, that will help a lot in making that identification.  If you have an unused barrel plug, that will also help.

Identify which jack lug is connected to the "hot" end/side of the plug, when the plug is inserted.  Now, remove the plug and see which other lug has continuity with that first one.  The firstlug is the one that goes to V+ on your board.  The second one is where your red wire from the battery goes to.  When no plug is inserted, the battery gets connected to the supply wire from jack to board.  Whenyou insert a plug, the battery connection is phsyically moved out of the way so that the connection is cut and replaced with the external power source.

make sense?

[primedynasty]

ok, just found this picture, and this is from small bear where i got my  jack, in fact i believe this is my jack


You advice is very helpful though, because I may not use this jack in the future and knowing how to test the jack will be critical.

Looking at this picture, where it says Board - / Battery -, is that going to the ring of the input jack?  and then the battery + goes to the red wire of the battery, and then board + goes to the board and to my led?  is that all correct?

[Mark Hammer]

Board/Battery-minus is ground.  Remember that barrel-style jacks on wall-warts used for pedals are generally outside-pos/inside-neg.

While that is a good jack, in that it is small, inexpensive, and durable, it also makes the chassis positive, rather than ground, unless you take steps to insulate the jack from the chassis.  Remember that the outside of the plug is positive, so it will rub against the threaded collet shown in the picture, which is then attached to the chassis by tightening the nut.  Oops, you now have V+ going to the box.   

While it IS possible to provide a physical separation of the jack and chassis (many ways to do it), many folks simply prefer to opt for the larger plastic chassis jack, so they don't have to do anything special to install it.

[primedynasty]

well i just happen to have one of those sitting at home.  So I can easily switch the two out.  However, I still am confused as to what gets connected to the ring of the input jack so that the battery or power only works when an input is plugged in.

[Mark Hammer]

Simplest thing is to stick a "naked" (no cover, no wires) barrel plugin a "naked" jack and see where the two solder lugs on the plug connect to.

[jayp5150]

Hook the negative lead from the battery snap to the ring of the input jack.

Battery positive to the switched lug on the DC jack, as stated above; DC jack positive to board positive.

The negative from the DC jack just connects to ground.

It is irrelevant if the DC jack is disabled when the input jack is unplugged, really. What you want to happen is for the battery ground to be disconnected with the removal of the input lead, and the battery positive to be disconnected when you insert the DC lead.

[primedynasty]

ok, thanks!