Requesting help debugging Green Ringer + using LTSpice

[crump]

I'm new to stompbox building and electronics in general, but have built a couple of kits from General Guitar Gadgets and am now looking to put circuits on a breadboard to learn more about how they actually work.

I decided to try out the Green Ringer from GGG, and have put the circuit together on my breadboard based on the GGG schematic:
http://www.generalguitargadgets.com/pdf/ggg_gro_sc.pdf

It is not working. I've read through the debugging topic in this forum, and spent some time poring over my build trying to figure out where the problem lies. The GGG instructions list voltages at the transistor pins (http://www.generalguitargadgets.com/pdf/ggg_gro_instruct.pdf). I'm using 2N5088 for Q1 and Q3, and 2N3906 for Q2. The measurements I get are as follows:

9v battery		9.25
Q1	C	6.15
Q1	B	1.85
Q1	E	1.43
Q2	C	6.76
Q2	B	6.10
Q2	E	1.88
Q3	C	9.25
Q3	B	4.35
Q3	E	3.75

The values for Q1 and Q3 all look close enough to me, but the Q2 values are all way off. I've looked at the portion of the circuit around Q2 and don't see anything wrong. I've substituted another 2N3906 at Q2, and also tried changing the orientation of the component in case I had it backwards, but neither change made any improvement. I'm a bit stumped now and not sure how to proceed.

So my next thought was to try using LTSpice to see the expected voltages at various points in the circuit to have something to compare my breadboard values to. I don't understand LTSpice (or electronics) well enough to make this work. This is my first attempt with LTSpice, and I put the components together as I thought they should be. Here is a screenshot of my LTSpice project:



There is probably something there I'm doing wrong (most likely with the input / output components), but I'm not sure. When I run the simulation I'm given a bunch of voltages and current measurements, but these have not been helpful so far as I need to figure out how to see the voltage at each transistor pin. Here's the output from LTSpice:

V(n001):    9    voltage
V(n007):    0    voltage
V(n008):    1.9812    voltage
V(n013):    1.35281    voltage
V(n010):    3.25163    voltage
V(n005):    5.10673    voltage
V(n004):    5.7324    voltage
V(n002):    4.47916    voltage
V(n009):    4.47916    voltage
V(n003):    4.27382    voltage
V(n006):    4.49491    voltage
V(n011):    3.63265    voltage
V(n012):    1.70735e-017    voltage
Ic(Q2):    -0.000325163    device_current
Ib(Q2):    -1.59748e-006    device_current
Ie(Q2):    0.00032676    device_current
Ic(Q3):    0.000362802    device_current
Ib(Q3):    4.6307e-007    device_current
Ie(Q3):    -0.000363265    device_current
Ic(Q1):    0.00021789    device_current
Ib(Q1):    3.03977e-007    device_current
Ie(Q1):    -0.000218194    device_current
I(C5):    -3.63265e-022    device_current
I(C4):    9e-016    device_current
I(C3):    5.76941e-020    device_current
I(C2):    -5.89021e-020    device_current
I(C1):    9.31162e-020    device_current
I(D2):    2.31535e-007    device_current
I(D1):    2.31535e-007    device_current
I(R12):    3.63265e-022    device_current
I(R11):    0.000363265    device_current
I(R10):    0.000204314    device_current
I(R9):    0.000204777    device_current
I(R8):    2.31535e-007    device_current
I(R7):    2.31535e-007    device_current
I(R5):    0.00032676    device_current
I(R3):    0.000216293    device_current
I(R1):    1.25336e-005    device_current
I(R6):    0.000325163    device_current
I(R4):    0.000218194    device_current
I(R2):    1.22296e-005    device_current
I(R13):    0    device_current
I(V2):    9.31162e-020    device_current
I(V1):    -0.00112317    device_current


Long winded first post, I'm sure. But I'm hoping someone here can give me some pointers about what to try next. Thanks!

[crump]

I put this project aside for a bit and have gone back a couple of times to try to debug further, but I'm still stumped. Based on the voltage readings at the transistor pins, there's something wrong between Q2 and Q3, since the voltage the Q2 base looks fine.

Can anyone give me some pointers about how to calculate the voltages I should see at each component between Q2 and Q3? I assume that each component in the circuit between the Q2 collector & emitter and the Q3 base have an effect on the voltage (R5, R6, C2, C3, D1, D2, R7, R8, R9, and R10 in the GGG schematic). I have checked each of the individual resistors to make sure they are the correct value with my multimeter, and they are fine. I'm not sure how to check that the capacitors are okay, but both C2 and C3 have the "473" marking so I assume they are correct. I suspect that the problem is the voltage going in to each diode, but I'm not sure how to calculate what input voltage I should expect at each diode, and what output voltage I should expect at each. I did put together an audio probe, and the audio signal sounds clean before each diode, and then sounds clipped after the diodes (it's a rough, uninteresting sound out of each diode individually).

I'm also stalled in my attempts to use LTSpice to determine the voltages expected at each component. Here is a repost of my first layout attempt:



I figured out that in order to measure voltages, I needed another simulation command, so I added a ".tran 700u startup" command:



Unfortunately when I measure the voltages at the transistor pins in this simulated circuit, I don't get values that match up with the GGG spec, so I must have something wrong here too.

Any advice is appreciated, especially involving how to calculate voltages at various points in the circuit, or how to edit my LTSpice project to effectively emulate the circuit so I can get reference voltages there.

[motorhead]

I can't really tell you what the problem is, however I have my experience with the green ringer, with the null mod

it didn't work either, and the pot I inserted in series with C2 was useless

I did a simulation using QUCS, and realised that in order to find the null, R6 has to be increased up to 33 k

I replaced R6 with a 50 k pot, and, surprise, using visual analyser (oscilloscope emulator), I found that my green ringer works fine, as long as I dialed the new pot until it reached the null point

I suggest you do the same

i can measure (or at least print the values from the simulator), if it helps

[gigimarga]

...

I replaced R6 with a 50 k pot, and, surprise, using visual analyser (oscilloscope emulator), I found that my green ringer works fine, as long as I dialed the new pot until it reached the null point
...

I am not very accustomed to use an oscilloscope, but how I can see this null point?
I tried to find it using my ear, but I had no luck....maybe because I used a 22k lin pot...

[crump]

Appreciate the reply motorhead. I left this project for dead a while ago when I ran out of debugging ideas, but will revisit it now and try your suggestion.

[LPDude]

I have built quite a few Green Ringers on Perf Board using the GGG schematic and it works every time. I am guessing since you are new to electronics and stompbox building you might have the transistor pinouts wrong. If you are laying the circuit out on breadboard just like it is shown on the schematic the flat side of the 2N5088/5089 transistors  in Q1 and Q3 should face to the right. and the flat side of the 2N3906 in Q2 should be facing left. 

[El Heisenberg]

I'd tell you to just rebuild the circuit on your breadboard. Various other things could be wrong, besides how you put the circuit together. The jacks you're using might have bad connections, or the breadboard is shorting out somewhere or something. When I get something on the breadboard and it's not working, I usually just rebuild it, if I can't figure out what I did wrong. There aren't that many places to go wrong, so it must be the breadboard.

[motorhead]

on the oscilloscope you can see very clearly how the wave is distorting so that the frequency doubles
hard to explain in words what happens

you don;t need a professional oscilloscope, just download VISUAL ANALYZER, it is free application for PC, and it uses the soundcard input for analysis, and the output for a wave generator