Two pedals with charge pumps (both) in one enclosure whine

[Atodovax]

Hello everyone. I just built two pedals (Klon Centaur and Echoplex Preamp) in one enclosure and when both are on the whine sound is very pronounced both pedals are dead silent if engaged alone. Do you know any solución? Or is It just to much to push to pedals with charge pumps stacked?. Both charge pumps are lt1054 and again, dead silent when played alone

[Slowpoke101]

The two charge pumps may be interacting causing a heterodyne whistle.
A single LT1054 should provide enough current for both effects so try disabling one charge pump and link the remaining one to the other effect. See if it helps.

[Atodovax]

The two charge pumps may be interacting causing a heterodyne whistle.
A single LT1054 should provide enough current for both effects so try disabling one charge pump and link the remaining one to the other effect. See if it helps.

Thank you for the advice!! That was my first though but i was not sure if i would fry It. So should i just remove the lt1054 ffom the Echoplex and jumper a wire from the +18 volt of the Klon Pcb into the V+ raíl of the Echoplex Pcb?

[Slowpoke101]

So should i just remove the lt1054 ffom the Echoplex and jumper a wire from the +18 volt of the Klon Pcb into the V+ raíl of the Echoplex Pcb?

I don't see any problem with doing that. You should not fry anything by doing so.

[antonis]

In case of not enough current from a single LT1054, an emitter follower (acting as current booster) should set things up..

[Ben N]

Assuming both are supposed to run at +18v! Charge pumps can be configured to do a variety of things with power, after all. If one of your circuits is designed to run on 12v and has some 16v caps, you would be in for an unpleasant surprise.

[antonis]

Is your other hobby some kind of "mind-terrorist", Ben ..??

[Ben N]

Hello, Antonis. At least the Eastern Mediterranean chapter of DIYSB appears to be open at this hour.
... mind-terrorist? I don't know exactly what that means, but I have to say it sounds pretty rad. I think.

[amptramp]

If you have one charge pump running at 40 KHz and another at 42 KHz, you will get sum and difference frequencies of 2 KHz and 82 KHz.  The 2KHz will definitely get into the audio.  A single charge pump would solve that so long as you have nothing else running at high speed.  An example of that would be the Paul Nelson pulse-width modulated phaser where you have high-speed chopping of a FET switch to simulate a linear resistance variation of an analog FET.

I am not that sold on charge pumps as a means of getting different voltages or polarities.  Their advantage is that they need no inductors or transformers.  The disadvantage is that they do introduce a fair amount of switching noise and inefficiency into the design.  A flyback or boost converter has the advantage of the turn-on of the inductor being relatively quiet because the current rise is limited by the inductance and switching on is a ramp rather than a step function.  (Switching off is still a step function but at least one part of the waveform has limited noise.) There are switching topologies such as resonant converters that are optimized for the reduction of noise.  You can buy converters of various sorts such as boost and flyback as complete entities from various suppliers, so you don't have to design your own.

There are converters for every purpose.  You can use a current-fed push-pull converter, a very weird design where both sides of a push-pull output stage are turned on at the same time and the input current flows through an inductor.  The regulation is inherently bad and you wouldn't use it anywhere you didn't have to but there is one application where it works and nothing else does: operation in the vicinity of a nuclear blast.   The nuclear blast turns on all semiconductor devices via gamma photocurrent and because the design is fed by an inductor, there is no sudden current rise and all devices survive whereas no other converter can protect its power devices.  Horses for courses.

[Ben N]

Now if someone REALLY wants to make bomb-proof pedals... Pete Cornish, are you listening?