Friday, November 4, 2022

Building a tube amp Fender Champ AA764 model copy

 It is a fender AA764 copy, with some mods: 

- Solid state rectifier (FRED diodes)
- Standby switch
- NFB pot and switch
- Two Fat switches
- One Bright and treble tone cap switch
- Master Volume
- Coupling cap value 6x switch (before the master vol pot)
- 6V6 Tung-Sol and 12AX7 Tung-Sol
- Orange drop capacitors
- EL84 paralell tube socket option (not tested). * Using one or another (6V6 or EL84)
- Presence switchable control
- Mid control
- TMB turn-off switch

** AA764 is a 5F1 with TMB tone control and a little diferent NFB.

champ - aa764


champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

champ - AA764

Optional EL84 socket:

EL84 vs 6V6

Sunday, December 5, 2021

Rhythmic values of notes


An attempt to understand and visualize rhythm notation...  

musical notation

musical notation
musical notation


* M -> Metronome click

Saturday, November 21, 2020

Vintage electronic magazines

Very good and easy vintage magazines about basic electronic

Hello friends, for the people in portuguese language, who are interested in electronic, and wishes it in a simple language, here it is, a periodic brazilian magazine of the 80's. Thanks to the professor Bêda Marques.

Click below:

Old magazines:

Electronic Magazines

Old stuff:

Eletronic boards

Thanks to:

Sunday, March 24, 2019

Bass Cut (ES 345 and Lucilly Varitone) for a Les Paul

Varitone or Bass cut - mod, lets cut some basses off (customized for a Les Paul)

Hello friends, now I became curious about the varitone circuit (bass cut circuit) used in the gibson ES 345, and decide to try a shot. After a lot of searching for the circuit at internet, I started making experiences in a les paul with a old pickup as the inductor, and I liked the results. Then I bought a new inductor ( 1,5 Henry - I guess) and capacitors, the result, after testing some capacitors values in series, is a custom version for les pauls as bellow, see the final schematic:


A six positions selector switch:

The 1,5 Henry inductor (I've used some hot glue to fix it):

Adding the capacitors and a resistor:

Don't forget:

The complete mod:

The chicken head knob and final result:


 New version 2.0:

** Ultimate version 3.0: **


Tone cap Updated:

The Orange Drop (22nF) tone capacitor mod:

Les Paus Orange Drop

It provides more balance and more bright tone.

Saturday, July 28, 2018

Les paul Pickup upgrade and magnet swap (Seymor Duncan 59 and Pearl Gates)

Les paul Pickup upgrade and magnet swap (Seymor Duncan 59 and Pearl Gates)

Hello friends, Its a humbucker pickups upgrade. I've got tired of my Burstbuckers (not pro) 1 and 2 copy, then I bought a Seymour Duncan Pear Gates Bridge (A2) and a 59 neck (A5), I guessed the 59 sounded a little boomy (lot of basses). The end of the history, I've swaped the pickups magnets: Alnico 5 to Alnico 2.
Now I have a Pearl Gates A5 and a Duncan 59 A2. Showed at the video below:

0:26 neck; 0:45 bridge; 1:05 both pickups

Tuesday, May 1, 2018

Headphone adapter to a 5W 5f1 champ

Headphone adapter to 5w 5f1 fender champ model, resistive passive circuit. Resistive load and a hight-pass capacitor switch (V2).



  • Values has been tested at a 5W amplifier, not higher.

  • Allways starts to use with the volume at minimal.

First version V1:

* 5n6 capacitor to produce a fake stereo effect




Second version V2:

  • Volume knob
  • left/off/right fake stereo effect switch

* Porta pro headphones are veeery good.

Wednesday, October 11, 2017

A twenty four fingerboard neck guitar notes chart

These is a map to the twenty four guitar neck, six strings and twenty four fingerboard. Each pentagram below is a guitar string.

The twenty four guitar notes

Monday, July 18, 2016

Stratocaster tremolo piezo + piezo mod

This is a mod to adapt a under saddle acoustic guitar piezo to a stratocaster block tremolo anda a common piezo inside the guitar body.


  • Use a rotary tool and a file to make a groove at the upside of the block:

strat block tremolo

strat block tremolo

strat block tremolo

  • ... until the piezo fit it, with only a small part outside:

  strat block tremolo 

  • Screw the other parts of the tremolo with the piezo wire out of the block:

*Maybe you will have to file the wood of the guitar under the bridge, a litle bit, to adapt the extra wire.

strat block tremolo

strat block tremolo

  •  Othewise, if you don't use the tremolo arm, like me, it is possible to use the other side of the block, making a extra hole to pass the wire:

strat block tremolo

strat block tremolo

  •   Set up the tremolo at the guitar, use the grounding hole to pass the piezo wire and conect it to the guitar circuit. Some hot glue will fix better some parts:

strat block tremolo

strat block tremolo
strat block tremolo

strat block tremolo

  •  Next step....fix a common piezo at the inside of the guitar body, near as possible of the bridge, using a double face tape:


strat piezo

 strat piezo

strat piezo

The tromolo piezo will have a lot of influence of the coils, producing a lot of reverbation. My sugestion is to mix the two piezos with a resistor (or a pot) like that:


strat piezo

* 1M or less... depends on the piezo output level.

Finaly, mixing the pickup mod ( with this piezo mod:

strat mod

*All pots are 500K

strat mod

* Other suggestions:


Tks to Pete from