Help needed with Boss CE-2 clone project

[Slowpoke101]

Hmm....

Omg, I've been doing it backwards?

Best laugh I've had all week  . But it explains some of the results. Don't feel too embarrassed, we all started off as beginners. I should have picked up on that you were injecting signals earlier. Now why doesn't the effect amplify at Q1 when you inject a signal or connect a guitar to it. Here's why;





Change the two capacitors as shown. You appear to be using capacitors in the pF range and not the nF range. So a 47nF and a 470nF are the correct ones to use. Very little useful audio signal would make it through such small value caps.

Let us know how you go.

[bluebunny]

Omg, I've been doing it backwards?

You just invented the signal injector!   

Don't sweat it - we've all done it.  My personal favourite is omitting to install the ICs, closely followed by plugging in my pedals back to front.   

And it gives us a chuckle, too.   

P.S. I get to give you your first "Like".  Now you've properly arrived, Paul!

[pgosselin]

Omg, I've been doing it backwards?

You just invented the signal injector!   

Don't sweat it - we've all done it.  My personal favourite is omitting to install the ICs, closely followed by plugging in my pedals back to front.   

And it gives us a chuckle, too.   

P.S. I get to give you your first "Like".  Now you've properly arrived, Paul!

Hey, don't knock it. I fixed two pedals using the signal injector...just not this one. 

[PRR]

> You just invented the signal injector!

Someone stole that invention over 100 years ago.

The original signal injector is a finger or screwdriver on the tube grid. Once we got AC lights, that should hum/buzz. I just saw the same trick in a 1960 electronics magazine, by guys with a benchful of fancier gear.

The tracer and injector are complementary. Just like a clogged vacuum cleaner hose. You look in the sucky end. Then you look in the end that blows. If not seen (or clogged with invisible electricity), you blow in the input and suck on the output. At least electrons don't leave a bad taste.

[pgosselin]

We have guitar signal! 

Well, gents, those two caps were the problem. (Can't believe I stuck in the wrong values in not just one place, but two places side-by-side).

I replaced them and lo and behold, not only do we have a guitar signal going all the way through, we have lots of swirly goodness.

So I guess that means the last step is to set the trimmer. Any pointers on doing that without a scope? Where should I set the depth and rate knobs before adjusting the trimmer? I understand I am supposed to back off the trimmer from the place where it begins to distort? What kind of distortion are we talking about? Are we talking overdrive type distortion or that sort of artificial "ticking" sound that I hear a lot of people complaining about? When I was playing with it, I did hear that kind of distortion and was able to back it off from that and make it go away without altering the effect too much.

I can't thank everyone who commented enough for all the help, especially you, Slowpoke101. I'm not sure I would have figured it out without you all.

Paul

[Slowpoke101]

You got it working  . That is great news. You must be very pleased.

Now, adjusting the trimmer is not too difficult. You have already noted a ticking noise coming from the LFO (TL022) and that adjustment of the trimmer can help reduce it. Set the rate pot to about 3 o'clock (fairly fast but not flat out) and the depth to max (fully CW). Apply a signal (pluck a guitar string - 4th string will do) and turn the trimmer until the chorus effect drops out - note the position of the trimmer, then do the same again but turn the trimmer in the opposite direction - the chorus effect will return and then drop out again the further that you turn the trimmer - note that position. Set the trimmer midway between those two positions. This is a coarse initial set-up.

The distortion that you will hear sounds like the signal is breaking up - it is. Keep plucking a guitar string whilst slowly adjusting the trimmer. You will hear certain points that sound a little crackly - that's the distortion - and the ticking noise may become noticeable. Back off from that point and turn the trimmer the other way until you hear the crackle (and possibly the ticking noise) again. This is the same thing as what you've just done before but you are trying to get the adjustment finer and minimise the ticking noise without disturbing the chorus effect. Really the best thing to do is to adjust the trimmer so that you are happy with the signal. Once you are happy with it test it with the guitar's other strings and some chords played slowly - the adjustment point (for best audio) is frequency dependant.

If it sounds good to you it is most likely set correctly. Now to enjoy playing with your new effect.

If the ticking noise becomes annoying let us know as there is usually a way to deal with it.

[bluebunny]

Initiation complete. 

[pgosselin]

Hey guys, here are some photos of the nearly finished pedal.

Why nearly finished? I thought I had the trimmer perfectly adjusted. No distortion. Not ticking. So I mounted it in the case. As soon as I put the lid on and fire it up, all of a sudden I hear the faint ticking. If I pull the bottom panel off and go to adjust it, the ticking goes away. Any suggestions on how to eliminate the ticking? Would shielded wires on the input, output or rate or depth controls help?

Thanks,

Paul

[Elijah-Baley]

My Zombie Chorus works fine, it gets ticking at extremely high setting but is not a big deal for me. Anyway, this is one of the reasons I included this CE-2 project (probably the modded version) and I don't wanna get any ticking issue this time!

I'm very interested in the solutions.

Edit:

I found this:
http://guitar-fx-layouts.42897.x6.nabble.com/boss-ce-2-ticking-td21858.html



"The mod is pretty simple if you want to add a separate voltage divider for the TL022.

(1) Remove link as shown.
(2) Add a 47uF cap to the upper right.
(3) Add two 10K resistors at bottom (gray)."

I think that's it.
Not verified by me, but seems it is ok.

I still didn't compared well with the Sabrotone version, which has the 47uF, I don't see the two 10k resistors instead, but I guess the schematic around the TL022 seems a bit different.
On Sabrotone nobody talk about ticking issue. I probably gonna build that one, crossing my fingers.

[pgosselin]

Thanks, Elijah-Baley,

That looks easy enough to try. And if it doesn't work, I can always restore it back to the original circuit.

Paul

[Elijah-Baley]

In that fourm the guy solved the ticking issue, but got a pop when engage the effect. Weird.
Anyway, let us to know.

[pgosselin]

Elijah-Baley,

I tried the mod tonight.

The pedal still works as before, but it does not get rid of the faint ticking. The ticking is definitely related to the rate knob since the ticking speed increases as the knob is turned.

Also, the revised illustration is deceptive where you add the 10K resistors. The 100n cap and the 1M resistor have to move from their original positions.

No pops whatsoever on the foot pedal.

So that means I am still looking for a way to reduce the ticking. It's only noticeable when I am not playing and volume is barely above the hiss of the amp. I can probably live with it, but the perfection in me wants to eliminate it if I can.

When adjusting the trimmer, I don't really get a lot of distortion (really only on one side) so there seems to be a decently wide area of the trimmer where the effect is strong and distortion free before the effect drops off on either side.

When I have the back off the pedal, it doesn't tick. It's only when I screw the back panel on. That makes me think it might be a shielding issue.

So, guys, are there any other strategies out there for knocking back the ticking noise of the LFO ?

Thanks,

Paul

[DrAlx]

Reducing ticking on that LFO.
1) Keep the rate pot wires as short as possible and as far from the audio path as possible. Worst ticking is at the highest rate setting because in that case the Rate2 wire is directly connected to the opamp output and sees the full square wave voltage swing and radiates it everywhere.
2) The bias voltage for the LFO should be set half way between the swing voltages of the square wave.  This may not be half the supply. On the lowest rate setting, measure the square wave voltage levels (on Rate3 pin), and then calculate the mid-point voltage. The schematic on Electrosmash shows a trimmer in the power supply section for setting the bias (which is labelled as 4.5v). Treat the 4.5v value as an approximation.  Its better to set it to the midpoint of the square wave.
3) There is an anti-tick mod used on some Boss pedals that involve smoothing  the square wave slightly. Mark Hammer has posted a reference on it.  It involves an extra cap and resistor. Look at the Tri-Vibe LFO as an example.

EDIT: I just looked again at the Electrosmash schematic and it seems the single trimmer sets both BBD bias and LFO bias. That is pretty horrible in my opinion.  Maybe the BBD bias and LFO bias are reasonably close to each other in that circuit.

[Elijah-Baley]

Sorry to hear that, this is pretty disappointed.

Are you using the "original" layout, right? The anti-ticking mod is based on the other layout, but the schematic is pretty the same.

To understand better the position of the 10k read the schematic here:
http://www.madbeanpedals.com/projects/PorkBarrel/PorkBarrel_2015.pdf
The two 10k resistor should be R28 and R29.

Or better look also this:
http://www.tonepad.com/getFile.asp?id=101
Here you can see the two 10k resistors (R33 and R34), but this one includes even the 47uF, C20.

What is I get is that the Guitar FX layout version is based on the original schematic:
https://www.electrosmash.com/images/tech/ce-2/boss-ce-2-schematic-parts.png
Of course the JFET Switching section is exluded.
In the layout has been included some mods taken from Tonepad and Madbean's Pork Barrel schematic.

The layout with the anti-ticking mod I linked above is based on the Madbean's Pork Barrel schematic, I see the two 10k resistors but I can't found the 47uF.

This is the Sabrotone version: http://www.sabrotone.com/wp-content/uploads/2013/04/ChorusEnsemble2.gif
I know is a bad deal, but if you really can't fix your build you can try the Sabrotone's layout.
I wanna quote some comment in the Tonepad report of the CE-2.

«shileded input/output wires are a must! ie from jack to switch to pc to switch to output jack. without this i couldnt get mine to stop ticking.»

«The sound is nice. I had some ticking at first, even with shielded cable, but just by moving the pcb a bit and by using a piece of self-adhesive copper tape around the output jack solder, I removed it.»

«You have to make sure the IN wire is either shielded or away from the LFO section, or you will get some slight ticking.»

«You MUST use shielded cable between input/output from jacks to switch, and between input/output from switch to board, with only one end of the shield in each cable connected to ground!!! Otherwise, you will get LFO ticking! Without it, there was ticking all over the place, once I used shielded cable, it was TOTALLY silent, wich means that the tonepad PCB works PERFECTLY!!»

«When I boxed the thing there was a ticking noise at first, i t disappeared when I turned rotated the board 180 degrees.»

[DrAlx]

So the two extra resistors in the mod listed by Elijah are just to give separate LFO bias. His diagram looks OK. Remove the long link so the LFO is not sharing bias with the audio/BBD. Then make a voltage divider from two resistors. Common point of the resistors is pin 5 if the IC. That is the LFO bias point. The other ends of the resistors go to pin 8 (IC positive supply) and to ground. You should not need to move the 1 meg or 100nF.
If you still get ticking using two 10k resistors, measure the square wave voltage at Rate 3 and see if the voltage swing is symmetrical about the bias level. In a similar LFO to this using an LM324 I found that i needed a higher bias voltage so used 10k going to supply and 12k to ground.

[pgosselin]

I'm going to try shielding the wires and the output jack first. Since the board stops ticking once I have the back off the pedal and the board is outside of the case, that makes me think it's things being crammed into close proximity inside the case that is making it tick. It's a tight fit inside my 125B enclosure.
I don't have a scope, so I can't check square waves, etc.

I originally chose the Guitar fx layout vs the Sabrotone one because it looked like it would be a better fit inside the case. Now I'm wondering if I should have just ponied up the $16 for the tone pad circuit board. But even they seem to have ticking issues.

Oh, well, it's the journey not the destination, right? That's why we do the diy stuff in the first place. The important thing is the pedal is working. Now, I'm just refining to make it work better.

Thanks,

Paul

[Slowpoke101]

The main issue with all these LFOs is that they generate a squarewave signal. The trick to reducing the switching noise is to slightly modify the waveshape. The following picture is a partial layout of the tagboard CE2 clone with the mods included. The modification involves installing the two 10K resistors, moving a 47uF cap (and a few other parts)but the main mod is to do with IC2. A 1nF capacitor and a 100K resistor.



Try it and see if it helps.

Just for interest's sake. The Sabro layout also ticks and the Tonepad layout also ticks (but not badly). The 100K resistor and the 1nF capacitor fixed them perfectly. Any effect that uses this style of LFO can and usually does tick to some extent.

I did send you a PM (personal message) yesterday with the picture but I was having access issues so it may not have been received.

Good luck.

[Elijah-Baley]

Fine. I'm really curious about this mod.
The position of the 100k resistor is really bad. I just watched quickly, I can't imagine a better position, now.

Could this 1nF-100k trick work even on Sabrotone layout?

[Slowpoke101]

The position of the 100K resistor is painful. I put the layout together rather quickly and I couldn't see an easy way of positioning it other than under the board.
The modification is based from a post by Mark Hammer. I usually put it in whenever I build something that uses that type of LFO.
It does work on the Sabrotone (?) layout - proven by forum member "ponce" late last year. Solved his ticking problem immediately.
Boss uses the mod as well in some of their older effects, eg: CE-3 Chorus. However Boss use a 10nF cap and not a 1nF cap. It doesn't really matter what value cap you use as long as it falls between 1nF and 18nF. Too small and the wave-shaping is insufficient and too high the wave-shaping becomes excessive and causes other fun issues.

You still need to use shielded cables for the input and output connections and be careful with internal cable layout - don't run the rate pot's cables directly over the input stages, etc. The cables still do radiate so care is required.

[pgosselin]

I did send you a PM (personal message) yesterday with the picture but I was having access issues so it may not have been received.

Slowpoke101, I just looked. It made it through, but it got caught in my spam folder.  Thanks taking the time to do it!

Paul