Ultra Flanger concerns. VOLTAGES.

[brokenstarguitar]

Once again I need some help or advice. I just built the John Hollis Ultra Flanger using the Sabrotone vero layout and having a few issues. The only way I can get it to flange is if im turning the "Manual" pot up and down. It wont flange on its own. I've been reading alot on this circuit but havent found anything similar. I've went over everything I could possibly think of, swapped all the ICs but still the same thing. Has anyone had the same or similar experience with this circuit? Can yous look over my voltages and let me know if you spot anything odd? Thanks guys!

Here's the layout I used........



Here's a link to pictures of my build........

http://s1300.photobucket.com/user/brokenstarguitar/library/Ultra%20Flanger?sort=3&page=1

Here's my voltages..........

IC1: TL072CP
1. 1.41
2. 8.40
3. 3.27
4. 0
5. 3.74
6. 3.27
7. 8.79
8. 9.49

IC2: TL072CP
1. 5.02
2. 5.03
3. 4.97
4. 0
5. 4.36
6. 4.39
7. 3.80
8. 9.49

IC3: CD4046BE
1. 0
2. 4.49
3. 4.85
4. 4.84
5. 0
6. 1.52
7. 1.49
8. 0
9. 1.36
10. 0.66
11. 0.23
12. 7.40
13. 0
14. 9.49
15. 0.10
16. 9.49

IC4: MN3007
1. 9.49
2. 4.75
3. 5.00
4. 0
5. 0
6. 4.39
7. 4.33
8. 4.33

IC5: CD4049UBE
1. 9.48
2. 4.76
3. 4.50
4. 4.76
5. 4.50
6. 4.76
7. 4.50
8. 0
9. 4.84
10. 4.40
11. 4.84
12. 4.40
13. 0
14. 4.84
15. 4.40
16. 0

[armdnrdy]

There doesn't seem to be a proper schematic with IC designations or pin numbers but...I'll give it a go.

It doesn't appear that your LFO is working.

The LFO looks like it's IC1 so...the LFO output is either pin 1 or pin 7.

The voltage should be moving up and down....according to the voltages you supplied...it's not.

Check for an uncut trace..uninstalled jumper, or solder bridge.

[brokenstarguitar]

I checked numerous times and it all looks good. I even went over the traces with a powerful magnifying glass and it looks good. I hooked the DMM up and while turning the knobs I noticed Pin 1 goes up to 1.52v when its turned all the way off (CCW). I don't know if that matters to makes sense to anyone. This has definately got me stumped. He's a schematic of the Ultra Flanger if it helps.

[Govmnt_Lacky]

Shot in the dark but....

It looks like the recommended op amp was a TL064. In the vero layout it looks like they broke that up into 2 dual op amps instead of a quad. What they also did was go from a low current style to a TL072.

I recommend swapping out at least IC1 with a low current style dual op amp like an LM358 or a TL022 or TL062.

See if that makes it wobble... 

[armdnrdy]

You should get the voltage swinging up and down on pin 9 of IC3 (4046)

Look around...I know you've been over the whole thing with a fine toothed comb and found nothing but...that's what I also thought under similar situations. 

[brokenstarguitar]

ok guys, I swapped both IC1 and IC2 in every combo I could with Tl022, Tl062, LM358, 4558, and it seems like it wants to flange with the 062 in IC2. I did notice that if I turn the "REGEN" all the way (CCW) off and turn the other controls I can get it to manually flange. I don't know if that helps at all.

I also checked the whole route from Pin 9 of the 4046 and nothing. At least nothing I can see under a microscope.

[brokenstarguitar]

Still playing with this thing and still nothing. Scrap pile?

[Govmnt_Lacky]

Did you verify ALL of the trace cuts? Even the tricky ones (under R15, etc.)

Sounds and looks to me like something was missed 

[DrAlx]

You should first check that the LFO is oscillating.  You can do that with a multimeter.
IC1 pin7 should be a square wave that jumps between high (around  8V) and low (around 0.6V).
Put the rate pot at maximum resistance.  Verify that the pin 7 voltage actually jumps between 2 extremes as described.
Not sure what the time period of the oscillation is for the Ultraflanger, so I'd wait at least 20seconds or so.  If there's no change, turn rate pot to halfway and try again.

EDIT.

If you don't get the oscillating voltage at IC1 pin 7, then I  would take all other ICs out of the board, and then test again with just IC1 in place.
If it still doesn't oscillate you will at least have managed to narrow down the number of things to check.

[brokenstarguitar]

DrAlx, the voltage stays at 8.40 on pin 7 of IC1. I turned the pot about 25% every 30 secs and it didn't move. I then followed your instructions and took out the other ICs and checked the voltage again. This time the voltage was oscillating but only from 8.40 to 8.41, back and forth, back and forth.

I also went over all the cuts and links again, for the thousandth time and theyre where theyre suppose to be, so I guess my issue is the LFO, correct?

I'm just so confused with this. EVERYTHING is in the correct place. It's wired correctly, I even went as far as to change the (C8) 1uf electrolytic going to IC3 pin 9. And changing the op amp doesnt work either. Where should i go?

[slacker]

Pull out IC1 and with the circuit powered up measure the voltages on the pins of the socket, what do you get?

[DrAlx]

DrAlx, the voltage stays at 8.40 on pin 7 of IC1. I turned the pot about 25% every 30 secs and it didn't move. I then followed your instructions and took out the other ICs and checked the voltage again. This time the voltage was oscillating but only from 8.40 to 8.41, back and forth, back and forth.

8.40 to 8.41 aint oscillating.
Here's a quick description based on your original voltage measurements in the thread.


The left  op-amp in the LFO in the schematic has pins 5,6,7 for +,-,out
The right op-amp in the LFO has pins 3,2,1 for +,-,out.

Now consider the left opamp.  Pin 6 voltage (inverting input) is roughly constant and reported as being 3.27V.
Pin 7 (ouput) is reported as 8.79V (i.e. +ve rail).
In order for pin 7 to go low, the voltage at pin 5 (non-inverting input) must go below 3.27V.
So when will that happen?
Well look at the voltage divider made up of the 100k and 47k resistors.
You see this...

    Pin7 -----  100k ----- Pin5 ------ 47k ------ Pin 1

Writing in the voltages

   8.79V ---- 100k ----- 3.27V----- 47k ---- Pin1

We know we want Pin5 to go to (below) 3.27V.
This will only happen if Pin1 goes sufficiently low. How low?
Well for pin5 to reach 3.27V the current through the 100k needs to go to
   (8.79V - 3.27V) / 100k = 0.0552 mA
When this happens, this current will cause a voltage drop across the 47k resistor
    47k * 0.0552 mA = 2.5944V
Therefore the voltage at pin 1 will be 3.27 - 2.5944 = 0.67V

So the voltage at pin 1 needs to go lower than 0.67V.
That is awfully close to a diode drop and it is entirely possible that the OP-amp output cannot swing that low.

You'll notice that the schematic says the pin 3 and pin6 voltage should be around 3.8V to 3.9V.
You only have 3.27V.  So that's the problem.  You need the pin3/pin6 voltage to be closer to 3.8 or 3.9V.
EDIT: (I am guessing you have somehow ended up using a 3.3V zener diode instead of the required 3.9V zener diode).

So try adding another regular silcon diode (e.g. 1N4148 or 1N4001) in series with the 3.9V zener.
Hook them together anode to cathode (ie. pointing in the same direction).
That will make the voltage at pin 3 and pin6 closer to the 3.8V to 3.9V range.

The alternative to try is to remove the 3.9V zener and replace it with a 12k resistor instead.
That should also shift the voltage closer to the 3.8V to 3.9V range.

[croopy]

are pins 3 and 6 supposed to be linked on ic1 ?

[DrAlx]

are pins 3 and 6 supposed to be linked on ic1 ?

Yes.
Pin6 is the inverting input of the left op-amp of the LFO and Pin3 is the non-inverting input of the right op-amp of the LFO.
Those pins should be at around 3.8V according to the schematic.  Not 3.27V as measured.

[brokenstarguitar]

DrAlx, the voltage stays at 8.40 on pin 7 of IC1. I turned the pot about 25% every 30 secs and it didn't move. I then followed your instructions and took out the other ICs and checked the voltage again. This time the voltage was oscillating but only from 8.40 to 8.41, back and forth, back and forth.

8.40 to 8.41 aint oscillating.
Here's a quick description based on your original voltage measurements in the thread.


The left  op-amp in the LFO in the schematic has pins 5,6,7 for +,-,out
The right op-amp in the LFO has pins 3,2,1 for +,-,out.

Now consider the left opamp.  Pin 6 voltage (inverting input) is roughly constant and reported as being 3.27V.
Pin 7 (ouput) is reported as 8.79V (i.e. +ve rail).
In order for pin 7 to go low, the voltage at pin 5 (non-inverting input) must go below 3.27V.
So when will that happen?
Well look at the voltage divider made up of the 100k and 47k resistors.
You see this...

    Pin7 -----  100k ----- Pin5 ------ 47k ------ Pin 1

Writing in the voltages

   8.79V ---- 100k ----- 3.27V----- 47k ---- Pin1

We know we want Pin5 to go to (below) 3.27V.
This will only happen if Pin1 goes sufficiently low. How low?
Well for pin5 to reach 3.27V the current through the 100k needs to go to
   (8.79V - 3.27V) / 100k = 0.0552 mA
When this happens, this current will cause a voltage drop across the 47k resistor
    47k * 0.0552 mA = 2.5944V
Therefore the voltage at pin 1 will be 3.27 - 2.5944 = 0.67V

So the voltage at pin 1 needs to go lower than 0.67V.
That is awfully close to a diode drop and it is entirely possible that the OP-amp output cannot swing that low.

You'll notice that the schematic says the pin 3 and pin6 voltage should be around 3.8V to 3.9V.
You only have 3.27V.  So that's the problem.  You need the pin3/pin6 voltage to be closer to 3.8 or 3.9V.
EDIT: (I am guessing you have somehow ended up using a 3.3V zener diode instead of the required 3.9V zener diode).

So try adding another regular silcon diode (e.g. 1N4148 or 1N4001) in series with the 3.9V zener.
Hook them together anode to cathode (ie. pointing in the same direction).
That will make the voltage at pin 3 and pin6 closer to the 3.8V to 3.9V range.

The alternative to try is to remove the 3.9V zener and replace it with a 12k resistor instead.
That should also shift the voltage closer to the 3.8V to 3.9V range.

YOU ARE AMAZING!!!! That was the issue. I tried putting a 4841 in series with the Zener but that took the voltage to 8.4. I then put the 12k resistor in which made a weird squeeling sound and no guitar signal. I then thought if the 3.9v Zener was only giving 3.27v and not the recommended 3.8-3.9v, thats a drop of 0.67v so then a 1n4731 Zener (4.3v) should be the answer. I put it in and tada!

I'm forever in your debt. Thank you so much!

[DrAlx]

Good idea to use the bigger zener. Glad it worked out.