Tremulus Lune Ticking

[Kearns892]

Hey guys,

I've been working on finishing up my tremulus lune build. I just got the speed control working well, but there is one final problem keeping this trem off my board. I get loud ticking when the Lune is both in bypass and engaged. I am using the Tonepad layout found here http://www.tonepad.com/getFile.asp?id=84. The only changes I have made were omitting the fine control, adding the ramp up ramp down mod (a version of the Symmetry control), and I made the suggested changes for the LFO on the Lune description page http://www.tonepad.com/project.asp?id=42, but NOT the audiopath changes.

I have searched for ticking solutions on the lune and here is what I have found and tried:
100uF Cap from +9v to GND
1nF Cap across the gain trim pot
Adjusting the gain pot

The only solution that had any effect was the trim pot, and it only made the ticking louder.

Are there any other suggestions you guys could come up with?

[therecordingart]

I'm not one to listen to for troubleshooting tips, but maybe a different value trimpot? Did you use the LDR in the BOM or did you make your own? Mine ticked as well, but only when the circuit was engaged. Adjusting the trimpot cleared it up.

[Hides-His-Eyes]

Try increasing the value of the resistor that goes to the LDR, and remove any flashing speed indicators.

[per_electric]

Hi!

To me this sounds like a typical grounding issue. The only part of the circuit that can possibly be affected when in bypass is the signal ground. I assume you've used the usual trick with a stereo jack at the input where the ring goes to chassis or some other sort of ground and one of the tips goes to the negative battery terminal? If this is the case, the LFO and the signal will share the same path to ground, and each time the LFO changes its current demand the voltage across your groundpath changes as well.
To verify that this might be your problem, try separating signal and other ciruit grounds. That is, isolate the input and output jack from the chassis, connect the negative battery terminal directly to the PCB (and disconnect it from the input jack), run a wire between the input and output jacks' ground terminals and also a wire from the input jack's ground terminal to the same point on the PCB where you connected the battery. Hopefully this will eliminate your ticking.
I remember having heard of a way to use a PNP transistor as a switch and then turning it on with the usual stereo jack trick. I've never tried it, but it shouldn't be that complicated. However, as long as you're not certain that this is actually your problem, there's no use implementing it yet.

Please let me know if you try this and how it turns out. I am also on the verge of building myself a tremolo, and all experience from others is much appreciated!!
Per

[Kearns892]

I'll look into separating the grounds. That sounds like it would have to be the issue considering it ticks in true bypass. Thanks!

@ Hides-His-Eyes I understand that removing my rate LED would reduce current draw, and make the ticking softer. But considering the box is drilled with labeling, and the rate LED provides a useful function, I would like to leave it in especially since the ticking will likely still be present, only softer. I will keep it in mind though as a last resort. Thanks for the input.

[Hides-His-Eyes]

ok then... make sure the LFO grounds and the signal grounds ONLY meet at the power jack.

[Kearns892]

Thanks a lot. Will do. If removing the LED is what must go, I will do it, but only after I have exhausted all other options 

[Kearns892]

I've been away from this for a while (school doesn't leave much time for debugging), but I am on break now and finally had a chance to separate the grounds. This did solved my ticking problem (on the tone pad layout I lifted the two 1k resistors that go to ground, connected those together and ran a wire straight to the power jack). However, in fiddling around to fix the ticks, I screwed something else up and now instead of a volume alteration that I got before, I get a constant signal with hiss coming in and out the chain as determined by the LFO. I can post some voltages in a bit, but I was only messing around with the 1ks and I had volume changes before so I am not sure what I could have done. Just hoping someone can point me in a direction to start looking.

Thanks

[trjones1]

This doesn't help your new problem, and you've already solved the ticking, but a cap across legs 6 and 7 of the LFO IC will also get rid of the ticking.  I think the size of the cap should be around 390-470pf.  It's a common problem on the Tremulus.  I don't know why that cap isn't just added onto the schematic permanently.

[Kearns892]

I had tried adding a cap there and had no luck. Not doubting it works in a lot of situations, but for me it seemed isolating the grounds was the only way.

[Kearns892]

Checked voltages on the ICs. My One Spot power adapter is giving me 9.51 volts.

IC1 (TL072):
1: 4.68
2: 4.68
3: 4.66
4: 0
5: 4.66
6: 4.68
7: 1.54
8: 9.51

IC2 (4558):
1: Cycles between ~2 and 7 volts
2: Cycles between ~2 and 7 volts
3: Cycles between ~2 and 7 volts
4: 0
5: Cycles between ~2 and 7 volts
6: Cycles between ~2 and 7 volts
7: 0
8: 9.51

If anyone has the proper voltages or sees something blatantly wrong please let me know!

[Kearns892]

Anyone have the voltages?

[space_ryerson]

I'm putting one together at the moment, so if no one responds, I should have voltages in a day or two.

[Kearns892]

Thanks. I have done some searching and I can't seem to find any voltages posted that are not from a unit someone is trying to debug. However, from comparing and contrasting I think I am narrowing it down. Please do respond with voltages though.