This is a very common problem: square waves generate sudden current draw that generate a "ticking" noise, quite aweful. However, I had noise trouble with the square wave setting.
To avoid that I separated the analog and digital ground, and connected them in one point with a big capacitor there. This is a very complex problem, and they are a lot of engineers out there that struggle with it (especially when designing cellphones). To avoid that, they should be well separated from the signal circuitery. Moreover, as I had to use long lugs pots, I would have to use "tall" 1590BB that are absolutely gigantic, so no thanks!Ī problem with LFO and high frequency digital devices is that they can generate noise.
I find that BB enclosures are really not fitted for a pedalboard: they take large amount of space horizontally and they are not very practical to use. There it is! Tracing the PCB was quite difficult, because I wanted it to fit in a 125B enclosure. A trimpot allows you to set the maximum brightness of the LED, to set the final volume and amplitude of the modulation. The D1 LED is external and let you see the waveform and tempo directly : you can directly see the LFO! A transistor then amplifies the current to light up the LED that will modulate the volume of the guitar. The LFO is delivered through pin number 5. The only problem is that it consider only the last two taps, no mean between several tapping, so you rather be quite precise when tapping the tempo. The PIC then calculate time between 2 activations and set the rate accordingly. When the tap tempo is activated, it connects the pin to the ground, which is detected by the PIC. The tap tempo is detected by the pin number 4 of the TAPLFO. Depending on the circuit we use for the LFO, the shape of this waveform can be different, generating different sounds: LFOs are very common when making music, especially with synthesizers: it generates a sound waveform with a given amplitude and frequency. To make the volume go up and down, we have to use a Low Frequency Oscillator (LFO). harmonic tremolo harmonique: initially developped in Fender "brown face" amps, it is a different kind of tremolo that alternatively changes the volume of bass and treble frequencies: when bass are up, trebles are low and vice versa.classic tremolo: changes the overall volume of the guitar.It is different from a vibrato that changes the pitch of the guitar rhythmically. How does a tremolo work? A tremolo modifies the volume of the guitar in a rythmic way. There is my version of relay bypass! It is a bit of a mess, because of my testing to reduce noise, but it fits! My goal now is to include everything on a PCB (jacks and relay bypass) to avoid a lot of wiring. "Hold" switch: allows you to choose between classical switching or temporary switching (the effect is on only while your foot is on the footswitch).Tempo subdivision switch: set the ratio between the tapping or rate knob and the rhythm of the tremolo 2:1 (the tremolo is twice slowler), 1:1 (same speed as tapping), 1:1,5, 1:2, 1:3 et 1:4!.Volume: can boost a bit the output signal.Waveform: 6-way rotary switch to choose the waveform: square, random, sweep, triangle, sin or "ramp up" waveform.Symmetry: changes the waveform, by modifying its duty cycle.Depth: set the tremolo's deepness, from very subtle tremolo to huge choppy tremolo!.Next, there are 6 potentiometers (many options!). This is nice to add some choppy stuffs while you play!
The little switch in the middle of the two LED (bypass LED, and tempo LED) allows you to switch the pedal temporarily. Indeed, 3PDT footswitches are the main reason for guitar pedal failure. That is a lot of knobs! You can already notice that t here are two footswitches: tap tempo (right side), and the true bypass footswitch that is a clickless relay bypass system! I used the relay bypass system that I conceived, which is completely silent, and more reliable than classic 3PDT true bypass.
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