"Little Angel" - Super Simple PT2399 Mini Chorus

[jfrabat]

OK, finally started the new Little Angel board.  Basically got everything in the board except for the 4.7K resistor (CLR), a 100uF cap (need to buy some), and the 2N3904.  When I got to the last component, I started looking in my parts to find it, but I noticed I did not have any.  Checked the old board, and noticed I have a 2N2222 in there.  Looked at my previous post, and I did mention it before, but there were no comments on it.  My question is, are they interchangeable?  It seems the only difference is the current they can handle (with the 2222 having more capacity)...  Is this right?

[EBK]

Correct.  2n2222 can handle more current.  Should be fine.  (And now, we know that you have working delay chips!)

[jfrabat]

(And now, we know that you have working delay chips!)

Right!  I am keeping the breadboard (I plan to build the Deep Blue Delay as a pedal, but will not use the components on the breadboard) so that if I suspect PT2399 lockup, I can use that to test it.

[EBK]

(And now, we know that you have working delay chips!)

Right!  I am keeping the breadboard (I plan to build the Deep Blue Delay as a pedal, but will not use the components on the breadboard) so that if I suspect PT2399 lockup, I can use that to test it.

Good plan!

[jfrabat]

This is where I am at now...



As you can see, I got a 470K resistor missing.  Checking my work, I noticed I had put a 470R in by mistake.  Since I was all out of 470K, I went to the store, and guess what?  They gave me 470R by mistake and I did not notice until I got home!!!  Argh!!!  Will have to get resistors on Monday now.

Anyway, I ditched the ceramic capacitors and used box capacitors instead.  All components are new, no carry over from the previous pedals...  The store was also out to 100uF caps, so I need to get that as well.

By the way, I am out of C500K pots; should I use A500K instead?  C is not really all that common in Costa Rica (I have B and A, but the A is Alpha and the B is a cheapo Chinese pot)

[jfrabat]

Here are voltages just taken from my Little Angel, which sounds the same as the breadboarded version I did you soundclips on. Speed at 3 o'clock, Depth at 12 o'clock:

PT2399

1:  5
2:  2.38 to 2.42
3:  0
4:  0
5:  2.75
6:  0.61
7:  0.88
8:  0.88
9 through to 16:  2.41 (slight movement)


NE5532

1:  0.13 to 4.9
2:  2.9 to 3.2
3:  2.7 to 3.1
4:  0v
5:  4.79
6.  4.9
7:  5.14
8:  9

OK, guys.  I am officially STUMPED and PO'ed!  This is the THIRD time I build this pedal, this time with ALL new parts (no recycled ones from previous tries), and I have EXACTLY the same result.  First time I tried etching my board.  Second and third I used boards from JMK PCB.  WHAT AM I DOING WRONG???

Here are my voltages:

Battery: 9.20V

TL082:
1: 4.68V
2: 4.68
3: 4.53V
4: 0V
5: 2.80 to 3.70V
6: 2.88 to 3.65V
7: 0 to 1.4V
8: 9.20V

78L05:
IN: 9.2V
GND: 0V
OUT: 5.01V

2N2222:
C: 0V
B: 0.449V
E: 2.43V

PT2399:
1: 5.01V
2: 2.5V
3: 0V
4: 0V
5: 3.40V (should be around 2.65V)
6: 2.43V (should be 0.61V)
7: 0.875V
8: 0.995V
9 to 16: around 2.5V with movements

PT2399 was tried out in the Deep Blue Delay BB, so it is working.  All caps and resistors were double checked, and they are correct (same with the previous board, which is still built).  here are some pics so that you can check if you see something I do not (and yes, the battery WAS plugged in when I tried it):











Any other ideas?  I cant believe I can build all other boards and not get this one to work!

[EBK]

Thought this was the fourth build.
Anyway, it is quite a mystery.  I did laugh as I instinctively looked at the soldering first, but in a good way.  I remembered where you started.  Soldering looks very good now (I've told you this before).  Your wiring is looking good too, but what is that black wire hanging out by itself and only connected at one end?

[jfrabat]

what is that black wire hanging out by itself and only connected at one end?

I miscounted the grounds.  It is just an extra ground.  I will de-solder it (most likely, I will replace the ground on top and replace it with this one)

[jfrabat]

Thought this was the fourth build.

Actually, you are right!

BUILD 1


BUILD 2


BUILD 3


BULD 4


I guess I have improved...  Practice makes perfect, right?   

Now if I could only get this darn thing to WORK!  What I cant understand is why i can get all the other pedals (Vulcan Rat, Deep Blue Delay, Screechy Cat, EA Tremolo, etc.) to work, but not this one (even after 4 tries!)...

[anotherjim]

2N2222:
C: 0V
B: 0.449V
E: 2.43V

These can't be right. E (Emitter) should be directly connected to 0v. Is board meant for 2N3904? Your 2N2222 may not be same pin order.

Anyway, I suggest you take this transistor out and see what it does then.

[EBK]

what is that black wire hanging out by itself and only connected at one end?

I miscounted the grounds.  It is just an extra ground.  I will de-solder it (most likely, I will replace the ground on top and replace it with this one)

What if you didn't miscount?
Perhaps try grounding that wire. 
When I have more time, I'll take another look at those voltages....

[jfrabat]

What if you didn't miscount?
Perhaps try grounding that wire. 
When I have more time, I'll take another look at those voltages....

Just tried it in case that was the issue...  No change.

2N2222:
C: 0V
B: 0.449V
E: 2.43V

These can't be right. E (Emitter) should be directly connected to 0v. Is board meant for 2N3904? Your 2N2222 may not be same pin order.

Anyway, I suggest you take this transistor out and see what it does then.

You are right: I mislabeled the ports.  E is 0V and C is 2.43V.  Base is correct at 0.049V.  Anyway, I double checked the pinouts of both, and theydo match:





I also used this information before making the swap. 

[maiko]

3904 2n2222 2n5088 2n5089 all the same pin out i use interchangeably No problems

[jfrabat]

Whatever is going on, I am pretty sure once I fix it, I will have 2 chorus...  Since the other one was doing exactly the same thing, they probably have the same issue.  By the way, I did not have and 500C pot, so I used a 500A wired backwards.  Not optimal, but it SHOULD work, right?

[maiko]

i got mine to work with "b" pots or linear taper

[stallik]

so I used a 500A wired backwards.  Not optimal, but it SHOULD work, right?

Err. if you wired it backwards, then it's probably working in reverse. ie when you think it's full on, its actually full off if that makes sense. I'd hate to think the pedal is working OK but you have the effect level at minimum..... sure you tried that but thought I'd mention it

[anotherjim]

I have to say that I really don't like the control current transistor arrangement. On power off, the 47uF timing capacitor is expected to discharge into the 5v rail via the reverse diode - however this diode could be 0.8Vf while we see the transistor BE is only 0.5Vf, so that diode is not really doing anything. I believe it is possible to power the chip up and down with the transistor always on so the chip has to start with 100R which we know is bad.
I repeat advice to take the transistor or 100R out!

[jfrabat]

OK, i did not get anything except try without the 100R resistor.  Is that correct?

[anotherjim]

Yes, the 100R, because that is a major difference between this circuit and the delays that work.

[jfrabat]

Do I replace it, jumper it or just leave the conection open?