Ticking tremolo

[demonstar]

Hey guys I designed this tremolo and it's ticking and it won't go away. I've searched the forum and this seems to be a pretty common thing. I've tried all of the ideas I've come across to reduce it but none have resulted in any decent reduce in ticking. I've tried putting up to 1000uF across the power supply to no avail.

The tremolo is really simple. It's a non-inverting opamp in a fixed gain arrangement to boost the input up then a transistor which is turned on and off by a lfo made out of a 555 timer. The transistor (2N3904) grounds the output signal to varying degrees. Depending on how firmly it is grounded is the depth. This is controlled by a pot. The signal is only grounded when the output of the 555 is high otherwise the signal passes untouched. This creates the pulsing tremolo. I'm using a standard pot arrangement on the output to control the level.

Hope thats clear. Any ideas on how to get rid of this annoying tick would be great?

Thanks 

[GREEN FUZ]

I`ve been on a bit of a Tremolo jag recently. Well, three and counting. The first, like yours, was based on a 555 LFO. I gave up trying to get rid of the ticking on that but may go back to it as it showed promise. The second was a Kay tremolo and while there was no ticking I wasn`t entirely pleased with the end result. The one on my breadboard at the moment is an R.A Penfold design using a Cmos 4011 as a square wave oscillator. It`s sounding good and the rate goes from very slow to pseudo Ring Modulator speeds but also exhibits ticking when the depth is reduced. Removing the depth control completely has solved it but it`s not really ideal. Still working on it.

If you have been reading as much as I have, by now you`ll have realised that there seem to be a few key tricks to reducing ticking.

1. Adequate supply line decoupling.
2. Separate oscillator section from power section as much as possible.
3. Use separate ground lines for oscillator joined at input or output jack. I haven`t worked out how to implement this but I`m still working on it.
4. Short screened leads from control pots. Again, isolated as much as possible from oscillator.

There are probably more but my brain is going a bit Gaga trying to sort through all this stuff.

Good luck.

[d95err]

Try a small cap across the supply rails that is soldered as close as possible to the 555, preferably directly onto the legs of the IC. That could work better than having a very big cap.

LFO's that origin from a square wave are prone to ticking because of the extremely abrupt change from maximum to minimum voltage. A sine LFO (e.g. a phase shift oscillator like on the EA tremolo) is much smoother and less inclined to tick.

[demonstar]

Thanks guys and hey greenfuzz I think you caught a bit of a trem bug. You hooked.

I'll try all of that as I've got it on the breadboard at the moment so things can change very easy.

If that fails I could try swapping the 555 lfo for a sine wave oscillator so it's more friendly on the power supply then maybe crop it into different shapes afterwards. I maybe should look at more examples of other tremolos too. I just hate layouts; I wish they were posted as schematics.  although I designed this one and came to it through my own means I'm sure others have done the same thing before. It seems a very simple concept. Despite this I think it sounds really good except for the ticking. Sometimes simple is best.


Here's another thought though...
                                               ... When I'm actually playing the ticking is actually not bad; I quite like it. It isn't noticeable but adds a nice choppiness and rhythmic feel to it. So, could I gate the power to the board so that power only flows to theboard when there is a input signal.


Or heres another thought...
                                       ...Run another 555 180 degrees out of phase that does nothing except keep the power even. (Bit of a waste though!)

[GREEN FUZ]

         ... When I'm actually playing the ticking is actually not bad; I quite like it. It isn't noticeable but adds a nice choppiness and rhythmic feel to it.

It seems that the effects of ticking can be masked by higher signal levels such as those put out by keyboards or high output guitar pickups. Perhaps a preamp in front of the tremolo circuit would boost the input signal enough to minimise the tick.

[nordine]

whats really cool about that circuit is that you're designing it 

555's (plain old ones) will almost always generate nasty ticking.. which infiltrates everywhere... indeed, if you change the LFO for a triangle or sine one, it'll probably stop ticking.. but, most likely it'll change the tremolo character, and maybe thats what you like about it most

i'll suggest, if every other option fail, a trick i used in a chorus that ticked: use a regulator to isolate opamp +V supply from the 555 supply .. which will get feed by the regulator voltage

hope this helps (it did to me)

[GREEN FUZ]

555's (plain old ones) will almost always generate nasty ticking..

Thanks for reminding me. Try using a Cmos 755 in place of the 555. It might help but that`s what I used in the first Trem and it still ticked.

[demonstar]

thanks. Ill go away and give the ideas a go and report back.

[smallbearelec]

Please check out my build-it article on the Tremulous Bear:

http://www.smallbearelec.com/Projects/TremBear/TremBear.html

It incorporates a basic that I picked up from R. G. Keen: separate ground planes for oscillator and modulator, joined only where the negative supply lead enters the board. Also note the capacitor on the CMOS 555 output, and the R-C decoupling. This design is nicely quiet, so feel free to use the appropriate pieces.

Regards
SD

[demonstar]

Thankyou very much Steve. I'll check it out and give it a go.

[demonstar]

I found a different lfo to use and that cured the spikes in the power suply but it still induces cliking in the signal when the lfo is connected but I'm getting there. I got to experiment with triangle waves a bit more.

Anyone whos interested, theres loads of oscillators here...

"http://www.educypedia.be/electronics/analogosciltypes.htm"

This is the one I'm using...

"http://ourworld.compuserve.com/homepages/Bill_Bowden/page8.htm#func.gif"

[demonstar]

Right, I'm now using my new lfo and I'm using it to turn on a relay which is switching in an extra resistor into the feedback loop (in parallel) to reduce the gain. It works way better than the transistor technique I started with. Because the oscillator wasn't able to switch the relay I used a transistor to sort that.

I now have just about NO tick in the signal. However, I know have a mechanical tick of the relay.  Anyone know an electrical alternative to the relay to avoid the mechanical click? It seems at the moment that I have to choose... mechanical click or signal tick!

I'm really pleased with how it's going. I've been able to keep the square wave sound I like. I'm a bit disappointed that although it sounds great through my marshall valve head and noisy cricket it sounds horrible through a solid state fender. Have other people found issues such as this? (Some pedals sounding great through one amp and bad through others) I found it with dist+ and amz mosfet booster but not with phase 45. hmmm.

Thanks again to everyone thats helped so far! I'm getting there and when I do get there this schematic will be publically available for personal use.

[nikStomp]

Use a optical resistor like the tremolous lune... is good..

[Mark Hammer]

1) The suggestion of using a CMOS 555 is good.  The tick arises from instantaneous current draw when the square wave is generated.  Make that current draw less and audibility of tick should be reduced.

2) A square wave does need to be THAT square.  The solution Boss and many others use is to set up the LFO to produce what is essentially a trapezoidal waveform.  That is, it rises and falls pretty quick, but not AS instantaneously as a true square wave.  Spreading out that sudden current draw so that it is not quite so sudden also dramatically reduces audible ticking.