Now my Ring Frobnicator works!

[hansl]

Now my Ring Frobnicator works!

The choice of LEDs is pretty sensitive. Today I purchased to packs of red LEDs, one pack 3 mm, 2.3 volts, 30 mA, and 5 mm, 2.3 volts, 30mA.

I replaced my two 5mm, any kind of red LEDs with two 3 mm, 2.3volts 30 mA, and put also one silicon diod in series. The voltage over the LEDs needs apparently to be 5.1 volts to get the oscillator to oscillate!

Next, I also replaced the LED3 with a 5mm 2.3 volts, 30mA.

Now the tremolo works, and the Ring Modulator, too......

Does anybody know the email address to RG Keen? I think I need to email him so he can put this to the errata?

BR,
Hans

[jrc4558]

Glad to hear it worked for you! Now I need toi try the same procedures! RG's contact information would probably be available somewhere on www.geofex.com

[jmusser]

I'll save this information to build by. I have been wanting to build this for awhile, but I have read about a lot of problems with it over the last couple months. I swapped Marty Mart for some 3080s which I guess are getting harder to come by, so I'm ready to try it. How does it sound? I've never heard a sound sample of it? The other John Hollis design I want to try is the "Rock Face", but I've heard it had some problems too. I can vouch for his Boost/Octave circuit. It sounds great. I have it so, I can switch the octave in and out. the octave really compliments the boost.

[Connoisseur of Distortion]

the frobnicator is not terribly hard to build... the trouble lies in getting it to work  :x

also, it is very noisy, with a pitch produced in the background. i, after building it, would advise you try something different... unless you intend to use it in a noise band or something  :?

[hansl]

Well I agree with Connisseur of Distorsion. The ring modulator is veeery special. There is a pitch in the background, which you can of course adjust to be almost quiet. I you hit a chord on the guitar, it would sound like the guitar is completely detuned. Indeed very odd. Probably not very useable. The tremolo is okey, actually somewhat special as the rate and depth can be adjusted some more, compared to other tremolos. I would build it for the tremolo.

I want to get the metallic sound out of a ring modulator and this device will not give that kind of effect, what I can see. I will build a passive one with small signal transformers and germanium diodes and experiment with that.
Probably making a mixer of some kind to mix the original signal and the processed, but I am not sure yet what the outcome will be. We'll see.

BR,
Hans

[brett]

Hi.  Passive ring modulators have much the same problems.  You'll probably need to get an AD633 or MC1496 chip and use one of the designs that use these chips to get really good results.

For semi-professional results (ie better than a Ring Frobnicator or passive ring mod, but not great) you might try this balanced modulator;
http://members.optusnet.com.au/~jethro.dog/mypic114.jpg
It uses common and cheap parts, and can almost get rid of the modulation frequency.  Note that the 555 timer is the CMOS type.

There's a pcb and overlay at my web site.

good luck

[octafish]

Brett, the modulatron is probably as good as you CAN get without an ad633 or mc1496 and a fraction of the price. Hansl check out the modulatron it'll stop you going crazy trying to balance transformers and diodes. I recomend adding a third socket for alternative carrier signals just add a break in the trace and use a normally closed switched audio jack. If you do this you should probably replace the trimmer with an external pot.

[hansl]

Well, I was partly wrong. The Frobnicator doesn't work as expected. The tremolo part is working very well, but not the Ring Modulator. The high pitch tone from a tone generator kind of device should not be there. The circuit works like a tone generator adding the pitch tone to the guitar input. But if you read the build instructions it should work another way.

I have replaced the 100nF cap with a 47nF cap, and when I set the frequency pot to "low" by turning it to the left, one can get a hint of how it should sound.
I suspect that the 100nF value is a too big cap that makes my circuit oscillate in an uncontrolable manner, and work more like a tone generator.
Tomorrow, I will go to my electonic parts dealer and buy a set of caps from a resonable low value up to 47 nF and try them out. My guess for the moment is that the C6 cap should be somewhere in the range from 10nF up to 47nF, it could even be lower, I don't know. Seems that hands-on testing is the only way to solve this last problem.

BR
Hans

[soggybag]

John Hollis' Titan Boost might work well as a passive ring mod with the addition of a few parts. I'm a total amature so this may be completely wrong. But from what I've read the passive ring mod needs a higher voltage signal to push it through four diodes and two transformers. The Titan boost is claimed (I haven't built it yet) to output up to a 30V signal.

[hansl]

Well, I was partly wrong. The Frobnicator doesn't work as expected. The tremolo part is working very well, but not the Ring Modulator. The high pitch tone from a tone generator kind of device should not be there. The circuit works like a tone generator adding the pitch tone to the guitar input. But if you read the build instructions it should work another way.

I have replaced the 100nF cap with a 47nF cap, and when I set the frequency pot to "low" by turning it to the left, one can get a hint of how it should sound.
I suspect that the 100nF value is a too big cap that makes my circuit oscillate in an uncontrolable manner, and work more like a tone generator.
Tomorrow, I will go to my electonic parts dealer and buy a set of caps from a resonable low value up to 47 nF and try them out. My guess for the moment is that the C6 cap should be somewhere in the range from 10nF up to 47nF, it could even be lower, I don't know. Seems that hands-on testing is the only way to solve this last problem.

BR
Hans

Forget what I have written above. It's completely wrong. I misinterpreted the schematic. It is not the C6 cap I was after. It is the C5 cap. Sorry for that! I have experimented replacing the C5 cap with somewhat higher values of the cap. The original value is 2n2, but I have experimented with 3n3, 4n7, 6n8, and 10 nF. To be honest there is nothing much of a difference, except you get closer to the trem effect. This thing doesn't sound like a Ring Modulator, it doesn't even come close. I would describe it as a mixing tone generator. When switching to the Ring modulator, the circuit acts like a tone generator, and the tone generator tone is mixed on top of the guitar sound. It doesn't affect the guitar sound at all. Very disappointing! The tremolo, OTOH works very well.

BR,
Hans

[hansl]

Hmmmmmmmmm...........

I think I have found the problem. The C5 cap gets into some problem. The difference of when the Frobnicator works for me and when it doesn't,  is very subtile. When it doesn't work it sounds like a tone generator mixed with a guitar. Like oil floating on water.

When it works, it sounds like a ring modulator with a bordun tone.

If I short-circuit the C5 cap with the battery turned off, and then turn it on, the ring modulator works. This makes sense as I got it working and then it stopped workning. Very frustrating indeed! This also makes sense as the tremolo is working, C6 is of a much larger value. I have also replaced the C5 with a similar 2n2 cap, and the problem remains, intermittently, so I don't think the cap is bad.

Since I have not mounted it yet into a box, this might be an earthning issue, or it might be a design problem, with a need for a fix.
I will mount it into my hammond box and then I will see..........

BR,
Hans

[puretube]

... has Paul P. seen this thread yet?  :wink:

[jmusser]

I'm hoping that this problem eventually gets resolved, as what it is supposed to do, is an effect I would like to have. There has to be some information that has been left out somewhere. I just don't believe that Mr. Hollis would stick an unproven circuit out there. Now, there is always the chance of an unproven schematic!

[hansl]

I'm hoping that this problem eventually gets resolved, as what it is supposed to do, is an effect I would like to have. There has to be some information that has been left out somewhere. I just don't believe that Mr. Hollis would stick an unproven circuit out there. Now, there is always the chance of an unproven schematic!

Well, now I have mounted it into an Hammond box. Now it seems to work as intended. Maybe it was an earthning issue, or something else, like me doing wrong. In Ring mode, it sounds like a classical ring modulator with a bordun tone. The tremolo is superb!. No, I don't think either that Mr Hollis would stick an unproven circuit out here. However, one have to have in mind that tolerances of components, like caps, and so on, might casue some trouble, when reproducing and building effects. You don't have the same components as the constructor. Well, I am pretty satisfied with Frobnicator now. Now to painting and marking. Towmorrow, I will start with my next project, John Hollis Omni Drive.

BR,
Hans

[soggybag]

I have a Frobnicator that originally worked then stopped working and I could never figure out why. Your thread has inspired me to get it working again.

It sounds like you added an extra diode in series with the two red LEDs to get the voltage across them to be 5V? Is it possible for you to post an image?

[jmusser]

Great news hansl! I'm glad to hear that you finally got it to work. It must be one of those finicky circuits. I have the stuff to put it together with, so this makes me feel better about starting it. I've really had good luck so far with the stuff I've built, but I haven't built anything real involved yet either. I'm getting an order together for the Harmonic Generator, and that ought to test me some.