SunTrem, 555 LFO based Tremolo

[deadastronaut]

yep...i certainly wasn't the first to use a 555 as a tremolo, or the first to use a 555/ led/ldr......

considering the 555 is around 40 years old i would have had to come up with it when i was 6, ..

anyway...

http://www.aronnelson.com/gallery/main.php/v/chickpea/TS555TINYTREM.gif.html

[Crontox102098]

try a distortion in front of it...see what happens..

I'm trying to do several different effects with the LDR and several opamp and transistors, so far I took a "Mini-Wah" and "Mini Envelope-Follower" based on two and one transistor OPAMP to do a buffer to the signal the guitar, I did not even see an outline example, doubly great!, and I had not thought of that .. i try with a simple transistor distortion to see what happens ...

Welcome!

You might want to also read this thread:  http://www.diystompboxes.com/smfforum/index.php?topic=87322.msg803784#msg803784

Thanks , That has no tremolo frequency limiter, itself, has no LFO, but thanks for the input;)

It's almost the same as yours except pins 4 and 8 are not connected and yours has a fixed resistor in series with the rate pot. The LFO is the 555 output to an LED/LDR pair.  Maybe I'm missing something, but it is essentially the same.

Essentially Yes...

So far I have only a square and triangular generators based on TL072, but I've still didn't managed to make the sinewave generator work.. I like the idea of the sawtooth, and what if we help each other and make a tremolo of 6 types of wave? Square, triangle, sawtooth, sine, (de flanco?) and pulse... not something crazy?"

Hey guys- I've stumbled on a simple way to take the square wave from an LFO and incrementally convert it to something approximating a sine wave using passive components. This is part of my "Turkey Day Contest" entry, so I can't post anything on it until I submit my entry in a few weeks. I'll be sure to post some schematics here after I submit my entry.

It would be great if you please sit down with that ... I'm killing myself to get the sine wave on the other hand you help someone else

The earliest circuit I've seen that uses the 555 timer in a tremolo application is a circuit from R.A. Penfold's book,  "Electronic Projects for Guitar" - it used a CMOS 555 timer to drive a JFet in series with a resistor on the input stage (guitar >resistor in series with JFET tied to ground).  The series resistance limits the loading effect on the guitar when the JFET is conducting fully, and there is another single transistor stage coupled to the JFET to boost the signal back up to unity gain or slightly above.  This book came out in 1980, I'm not aware of any commercial circuits or published schematics that came out before this time......

That was my idea, but I opted for the LDR through a condenser that this is not the pop-pop hits in the amplifier.

yep...i certainly wasn't the first to use a 555 as a tremolo, or the first to use a 555/ led/ldr......

considering the 555 is around 40 years old i would have had to come up with it when i was 6, ..

anyway...

http://www.aronnelson.com/gallery/main.php/v/chickpea/TS555TINYTREM.gif.html

Hahahaha I was not born when these components were built and no one has said who was the first to use them, is like saying Tim Escobedo stole the idea to Dallas Arbiter ...

Everyone does what he wants with the way we make it work better.

[Jdansti]

Right!  I used a 555 to build a metronome for a high school electronics class in 1978 or 1979. Not only have they been around for a while, but they're very versital. From sending out a continuous pulse like we're using for our LFOs, to a one-shot pulse, to flip-flop, to voltage multiplier, to voltage controlled oscillators, and a lot more.

I'll share my research here and follow up after the contest to show how my version works. The following are three examples of how to shape the 555 output signal. 

http://www.electronicspoint.com/attachments/1011d1285665527-convert-square-wave-sine-wave-sine-wave-output.jpg



http://www.designnotes.com/downloads/MK105_Assembly.pdf



http://i1160.photobucket.com/albums/q485/jdansti/4EE9FB92-C796-49ED-B679-F75F007960C9-206-0000001B34F7B5B7.jpg



Steve's Tremulous Bear uses another method to modify the waveform, and might be best for minimizing some of the limitations I found with the methods above and described below.


I've played with the first and third method above and noticed several things.

1) As you make the waveform more sine-like, the attack of the sweep becomes more ramped or drawnout, but the decay is still pretty sharp. It gives the guitar signal a "backward" sound - kinda' like shhhhhhhhhp. This happens regardless of the duty cycle of the square wave. I don't know if this is a limitation of the filtering methods or if it is being caused by the LDR's on/off ramps.  I don't have a scope to help me figure out what is causing the long attack/short decay.

2)  In the first example above, I tested the output at each node where a cap is connected. It definitely goes from saw at the first cap to more sine-ish at the last cap. I noticed that the signal got progressively smaller at the second and third nodes. I assume that this is partially due to the increased resistance caused by the resistors in series. I used a Tillman preamp on the front end to provide a good signal through the LDR.

3) As you get closer to a sine wave, you lose the signal as you increase the speed. With example #1 tacked onto the 555 output, faster speeds work better with square waves than sine.

4) I experienced a lot of interaction between the filters and the timer's speed. I can't recall if the speed increased or decreased as I got closer to the sine waveform. This might have been caused by the types of filters I was playing with.

5) In example #1, I found it best to increase the capacitance of the second and third capacitors. I also reduced the resistance for the resistors toward the right to avoid making the LED too dim.

Anyway, there's a few ways to modify the waveform. I don't guaranty that any of them will sound very pleasant, but it's something you can try.   Good luck!

[Mac Walker]

Hey guys- I've stumbled on a simple way to take the square wave from an LFO and incrementally convert it to something approximating a sine wave using passive components. This is part of my "Turkey Day Contest" entry, so I can't post anything on it until I submit my entry in a few weeks. I'll be sure to post some schematics here after I submit my entry.

It would be great if you please sit down with that ... I'm killing myself to get the sine wave on the other hand you help someone else

Dual ganged pot on the rate potentiometer, the additional pot controls a passive RC filter on the square wave output?  Proportional to 1/R, so for a first order passive filter match the 3db point to your pulse frequency, or as close as reasonably possible.  Should be close to a sine wave then.  Some amplitude loss could be compensated by changing your depth adjustment.  Question is, linear or audio taper?  Might work, might not, I hope this translates OK!

Dammit, there I go reinventing the wheel again!

[Mac Walker]

Oh yeah, before I forget, here is a good reference that explains vactrol VCA's (tremolo) applications, geared more towards static applications but relevant in this case....

http://www.silonex.com/audiohm/pdf/levelcontrol.pdf

[Crontox102098]

Right!  I used a 555 to build a metronome for a high school electronics class in 1978 or 1979. Not only have they been around for a while, but they're very versital. From sending out a continuous pulse like we're using for our LFOs, to a one-shot pulse, to flip-flop, to voltage multiplier, to voltage controlled oscillators, and a lot more.

I'll share my research here and follow up after the contest to show how my version works. The following are three examples of how to shape the 555 output signal.  

http://www.electronicspoint.com/attachments/1011d1285665527-convert-square-wave-sine-wave-sine-wave-output.jpg



http://www.designnotes.com/downloads/MK105_Assembly.pdf



http://i1160.photobucket.com/albums/q485/jdansti/4EE9FB92-C796-49ED-B679-F75F007960C9-206-0000001B34F7B5B7.jpg



Steve's Tremulous Bear uses another method to modify the waveform, and might be best for minimizing some of the limitations I found with the methods above and described below.


I've played with the first and third method above and noticed several things.

1) As you make the waveform more sine-like, the attack of the sweep becomes more ramped or drawnout, but the decay is still pretty sharp. It gives the guitar signal a "backward" sound - kinda' like shhhhhhhhhp. This happens regardless of the duty cycle of the square wave. I don't know if this is a limitation of the filtering methods or if it is being caused by the LDR's on/off ramps.  I don't have a scope to help me figure out what is causing the long attack/short decay.

2)  In the first example above, I tested the output at each node where a cap is connected. It definitely goes from saw at the first cap to more sine-ish at the last cap. I noticed that the signal got progressively smaller at the second and third nodes. I assume that this is partially due to the increased resistance caused by the resistors in series. I used a Tillman preamp on the front end to provide a good signal through the LDR.

3) As you get closer to a sine wave, you lose the signal as you increase the speed. With example #1 tacked onto the 555 output, faster speeds work better with square waves than sine.

4) I experienced a lot of interaction between the filters and the timer's speed. I can't recall if the speed increased or decreased as I got closer to the sine waveform. This might have been caused by the types of filters I was playing with.

5) In example #1, I found it best to increase the capacitance of the second and third capacitors. I also reduced the resistance for the resistors toward the right to avoid making the LED too dim.

Anyway, there's a few ways to modify the waveform. I don't guaranty that any of them will sound very pleasant, but it's something you can try.   Good luck!

OMG!!! GREAT... GREEEEAAATTT I obtained the sine wave from a square wave , Right now I am still tell as resistors and capacitors changing aver that comes out better.

I test other way:

                    1K            470   LED
555 -> Out----\/\/\----------\/\/\--->|---GRND
                              |
                             __ +
                             ---       200uF
                              |
                           GRND

[Jdansti]

Oh yeah, before I forget, here is a good reference that explains vactrol VCA's (tremolo) applications, geared more towards static applications but relevant in this case....

http://www.silonex.com/audiohm/pdf/levelcontrol.pdf

Thanks for the info. I scanned through it and it looks like some good stuff. I've got it in my reading list!

[Jdansti]

@Mauricio > take long to start and I have no idea why.

Could you please explain?  The chip doesn't oscillate when you turn it on?  The chip oscillates but the LED responds too slowly?

[Crontox102098]

@Mauricio > take long to start and I have no idea why.

Could you please explain?  The chip doesn't oscillate when you turn it on?  The chip oscillates but the LED responds too slowly?

We solved the problem ... I used a 2200uF capacitor and I did not realize ... : icon_eek: ... what I did was change to 220uF.

                   1K            470   LED
555 -> Out----\/\/\----------\/\/\--->|---GRND
                             |
                            __ +
                            ---       200uF
                             |
                          GRND

Specifically this schematic, R3 are 10K

[Crontox102098]

Anyone know how to improve the tremolo? with more separation, soft stuff ...

[Jdansti]

Steve (Small Bear) has a couple of features on the Tremulous Bear. He has two speed pots which interact with each other to allow you to adjust the duty cycle. You can adjust the duration of the cycles to have long or short time at zero or anywhere in between. He also uses a diode between pins 6 and 7 to quickly give you a 50/50 duty cycle.

For your filter, you could set up a chain of resistors and capacitors instead if just one and use a rotary switch to select how much "smoothing" you want. That way your last capacitor could be large enough to give you a very smooth waveform when the speed is set low. You'd have to reduce the resistor values if you chain several together or the LED might not light.

If you're not using a booster or buffers, you might want to put a small capacitor across the LDR the same as you would on a guitar volume pot to avoid losing the highs as the LDR sweeps.

[Jdansti]

@Mauricio > take long to start and I have no idea why.

Could you please explain?  The chip doesn't oscillate when you turn it on?  The chip oscillates but the LED responds too slowly?

We solved the problem ... I used a 2200uF capacitor and I did not realize ... : icon_eek: ... what I did was change to 220uF.

                   1K            470   LED
555 -> Out----\/\/\----------\/\/\--->|---GRND
                             |
                            __ +
                            ---       200uF
                             |
                          GRND

Specifically this schematic, R3 are 10K

Right. The problem I have with this filter is that I can't get a symmetrical waveform. I get a slow rise and quick drop like this:



Anyone know why this might be and how to improve the symmetry?

[Crontox102098]

@Mauricio > take long to start and I have no idea why.

Could you please explain?  The chip doesn't oscillate when you turn it on?  The chip oscillates but the LED responds too slowly?

We solved the problem ... I used a 2200uF capacitor and I did not realize ... : icon_eek: ... what I did was change to 220uF.

                   1K            470   LED
555 -> Out----\/\/\----------\/\/\--->|---GRND
                             |
                            __ +
                            ---       200uF
                             |
                          GRND

Specifically this schematic, R3 are 10K

Right. The problem I have with this filter is that I can't get a symmetrical waveform. I get a slow rise and quick drop like this:



Anyone know why this might be and how to improve the symmetry?

You could, but I have no idea how, my hypothesis is seeking a number of farads its accuracy and generate the necessary symmetry, but that's impossible, I think.

[Jdansti]

You could, but I have no idea how, my hypothesis is seeking a number of farads its accuracy and generate the necessary symmetry, but that's impossible, I think.

220uF gives a pretty good front end ramp, but the tail still drops pretty quickly. 470-1000uF is even smoother on the front end, but I still get a quick drop on the tail.  I think smooth ramp on the front end is because the capacitors take time to charge. The quick drop on the tail is because when the square wave from the 555 goes to zero, the capacitor quickly discharges to ground. It seems that I need a way to slow down the discharge rate without affecting the charge up on the front end.

I just need to get a scope on it to know for sure. I think my brother has one of my Dad's old scopes that he's not using. I need to borrow it and see what's really going on.

[Crontox102098]

You could, but I have no idea how, my hypothesis is seeking a number of farads its accuracy and generate the necessary symmetry, but that's impossible, I think.

220uF gives a pretty good front end ramp, but the tail still drops pretty quickly. 470-1000uF is even smoother on the front end, but I still get a quick drop on the tail.  I think smooth ramp on the front end is because the capacitors take time to charge. The quick drop on the tail is because when the square wave from the 555 goes to zero, the capacitor quickly discharges to ground. It seems that I need a way to slow down the discharge rate without affecting the charge up on the front end.

I just need to get a scope on it to know for sure. I think my brother has one of my Dad's old scopes that he's not using. I need to borrow it and see what's really going on.

This is not only for my guitar and share with others what I am using for a project of the University .. As you know if you got you help me regulate the wave?

[Jdansti]

[quote author=Crontox102098 link=topic=99839.msg876588#msg876588 date=
This is not only for my guitar and share with others what I am using for a project of the University .. As you know if you got you help me regulate the wave?
[/quote]

I'll post what I learn about this here.

Since this is for your university project, have you discussed this with your professors?  Maybe they could shed some light on this.

[Crontox102098]

[quote author=Crontox102098 link=topic=99839.msg876588#msg876588 date=
This is not only for my guitar and share with others what I am using for a project of the University .. As you know if you got you help me regulate the wave?

I'll post what I learn about this here.

Since this is for your university project, have you discussed this with your professors?  Maybe they could shed some light on this.
[/quote]

He told me what the capacitor, but it should improve ... the LFO must not have a drop to 0 so abrupt.

[Crontox102098]

Please do not leave the topic, I need ideas for regulating the wave, please ...

[Jdansti]

I'm still here...


I spent 3 more hours last night trying to get the 555 output to be symmetrical triangle or sine and was unsuccessful. It might not be possible. 

The "Tremulous Lune" is a good tremolo that is capable of a symmetric waveform. I recommend it if you want a symmetric waveform.

Here's the schematic: http://fuzzcentral.ssguitar.com/tremulus.php

And here's the symmetry mod:

http://www.diystompboxes.com/smfforum/index.php?topic=65107.0

[Crontox102098]

I'm still here...


I spent 3 more hours last night trying to get the 555 output to be symmetrical triangle or sine and was unsuccessful. It might not be possible. 

The "Tremulous Lune" is a good tremolo that is capable of a symmetric waveform. I recommend it if you want a symmetric waveform.

Here's the schematic: http://fuzzcentral.ssguitar.com/tremulus.php

And here's the symmetry mod:

http://www.diystompboxes.com/smfforum/index.php?topic=65107.0

MAN! ARE COMPLETELY GREAT, GRE-AT, a wave goes totally perfect (I have a tiny scope)