Tonepad's Maestro FSH-1 has a strong ticking

[gigimarga]

Hello,

After I've tested a lot of transistors for noise, i liked very much a BC337.
My only problem is now that i have a strong ticking (that i had anyway with any transistor that i tested...and, what's important, i used ONLY alkaline batteries):
http://www.aronnelson.com/DIYFiles/up/fsh.mp3 (i used a rocktron rampage as distortion)

What can i do?
I searched the forum, but i don't find anything very clear...

Thx a lot!

[eggman6]

I believe ticking is a common problem associated with this circuit.

[gigimarga]

Thx eggman6...i hope that i will resolve it because i like it a lot!

[gigimarga]

 

[gigimarga]

 

[frequencycentral]

The ticking is LFO leakage into the audio path. You could try getting rid of it by using a capacitor/resistor pair configured as a highpass filter. Try a 0.01 or 0.027 at the end of the audio path with a 100k resistor to ground immediately after it.

Like this: (ignore the square in/pulse out bit)



Basically it should defeat the LFO by not allowing frequencies through below the HPF cutoff.

EDIT: I had similar ticking in a tube tremolo I designed ("Bipolar Disorder"), and this is how I solved it.

[gigimarga]

Thx a lot frequencycentral!

I have two questions regarding the filter:

1) the 10nF capacitor must to be electrolytical or not?
2) where i must to put the filter: before the output jack (easy) or after the LFO (very hard...i have no ideea where is that...)?

Thx a lot again!

[frequencycentral]

Ok just looking at the schematic here: http://www.freeinfosociety.com/electronics/schemview.php?id=1125

C4 and R14 are actually configured as a HPF. You should try increasing the value of C4, maybe just add another 0.15 in parallel. No it doesnt need to be polarised. You need to strike a balance between stopping the ticking at the LFOs highest speed and cutting the bottom end off your guitar signal.

Also, look at C7 - try anothyer 0.15 in parallel there too.

Get some crocodile clip jumper leads and play about.

I hope this sorts it for you! I haven't built the FSH as I have all that stuff available in my modular synth.

[gigimarga]

Thx a lot again!

I will try what you said tonight...

[frequencycentral]

Hope it works out for you, just keep upping the cap value until optimum.

[returntable]

did it work?
I have exactly the same problem with my build... would be nice to solve the problem somehow.

[gigimarga]

Sorry, but i hadn't time to test...i was gone from my home for a couple of days...maybe tomorrow...

[gigimarga]

I've tested what frequencycentral suggested to me above, but i still have some ticking.
Even i replaced the 100nF capacitor from the output with a smaller one (47nF, 33nF, 22nF, 10nF and...1nF) the ticking is still audible and, of course, i lost almost all of the bottom end 

[returntable]

that's a pitty. I hope someone can help us soon.

[flo]

Hi, if the problem is due to LFO ticking "bleeding through" to the audio path, there are several things that you can do.
I found the following tips on this site when I was looking to cure LFO ticking in an UltraFlanger. The following tips were written by various people (Mark Hammer and others) and were used to address deticking LFO's in general but I'll try to rewrite it to make it appropriate for deticking the FSH LFO:

http://www.diystompboxes.com/smfforum/index.php?topic=61250.msg480708#msg480708

There are a few separate matters to be addressed (quotes from others slightly rewritten to adress the FSH LFO):

The LFO and audio path need to be decoupled from each other.  You should run something like a 100R resistor from the shared +9v source to the V+ pin of the LFO opamp chips (especially IC5 which generates the LFO), and run a 10-100uf cap to ground from that pin.  This will give each chip a small reservoir of current to hold them over in case one of the other chips makes a sudden demand for current.  Those sudden demands are what you hear as ticking.
The FSH is using a 741 opamp for the LFO path (IC5) and 3080 OTA's for the (filter) audio path (IC1 IC2 Q1 Q2).  This will let you decouple them separately, instead of having whatever the LFO does impact directly on the OTA's in the same hunk of epoxy.

It is also a smart idea to use a low-current op-amp for the LFO.  Why?  Because the "standard" opamp LFO produces a square wave.  What you hear as ticking is the sudden current draw as the square wave rises, placing noise on the power line.  The decoupling reduces the extent to which that spike "bleeds" into other parts of the overall circuit.  Using a low-current op-amp reduces the magnitude of that spike in the first place.  Think of the decoupling as being like ear muffs, and the low-current op-amp as being like smaller speakers.  Use of either will keep the volume of undesirable sounds down, but use of both will reduce it even further.
You will note in glancing through schematics of commercial phaser, flanger, chorus, and tremolo pedals that many of them will use either an LM358 or a TL022 dual op-amp for the LFO, and use different op-amps elsewhere in the audio path.  They use those particular op-amps because they draw less current.  There are other functional equivalents, I'm sure.  I just wanted to explain why you often see those ones.

Another strategy for deticking involves a slight change to the LFO design itself.  Nicholas Boscorelli explains this nicely in one of his Stompboxology ( http://moosapotamus.net/IDEAS/stompboxology/stompboxology.html ) newsletters, and you can sometimes see this in commercial designs.  The gist is to change that initial square wave into what is more or less a trapezoidal wave.  What we hear as ticking depends on the suddenness of the rise-time.  If the rise-time can be slowed down even just a wee bit, the current draw of the LFO is essentially distributed over a long enough period of time (in electronic, not human, terms) that it does not produce disturbances elsewhere in the circuit.
So, reduce the amount of current required to produce a square wave, make the rise-time of the square wave less sudden, and isolate the chip requiring the sudden current draw from the rest of the circuit.  That's how you get a tick-free modulation pedal.
"In my Small Stone (russian) I have a 1uF capacitor between + and - input of the comparator opamp which is the one that produces the square wave of the LFO. This seems to detick the Small Stone, probably, by reducing the rise time of the square wave."

[jimbob]

In my Small Stone (russian) I have a 1uF capacitor between + and - input of the comparator opamp which is the one that produces the square wave of the LFO. This seems to detick the Small Stone, probably, by reducing the rise time of the square wave

Clever- Is this also an issue with the DIY (Tonepad) Small Stone version?

[flo]

Sorry, I do not know, I have only a "Russian" one.

[gigimarga]

WOOOOOOOW...thx a lot flo for your advices...i will try them as soon as possible...

[gijimmbo]

let me know if that works.  i am now noticing a tick too.
it's not that bad, if there is an easy fix though, i'd like to try it out.
thanks again

[flo]

> "thx a lot flo for your advices"
You're welkom but I can't take the credit for the wisdom of it. They are just advices from others on this forum (like Mark Hammer: Thanks!) that I collected. I only adjusted them a bit for you to "fit" the FSH. Try a search on "ticking LFO" / "deticking LFO" and you'll find the same advice... Good luck fixing it!