Dual TBridge Percussion

Concept

The TBridge circuit was used in some famous analog drumcomputers. It is possible to create different drumsounds like bassdrums, toms, claves and more. The circuit was developed during the Homemade summercamp 2014 in Fou de Fougerette by Uwe Schueler, Tamara Wilhelm and Oliver Jaeggi.

On the board are 2 TBridge sounds circuits that can be played separately.

Parts

• 1* TL082P op-amp

resistors

• R3,4,13,14,16,17,25,26,27 RESISTOR_100k

• R6,7 RESISTOR_2M , 4M used for different decay range of first sound

• R18,19 RESISTOR_1.9M, 3.8M used for different decay range of second sound
• R11 RESISTOR_10
• R23 RESISTOR_5.6

• R10, 22 ALPHA_POTI 1k ALPHA_POTI for frequency of the percussion sound

capacitors C8, 9, 20, 21 CAP_100n C12, 15 CAP_4.7u pol C5 CAP_47u pol C1, 24 CAP_10n

• 2* switches (on-off-on) select the decay ranges
• 4* jack connectors (2 * trigger in / 2 * audio out

Schematics

A Dual OpAmp is used for 2 TBridge Oscillators. The Potentiometer controlls the frequency of the oscillator. The decayswitch selects different decay times of the sound (this also affects the frequency).

Board

Mask (bottom): File:DualTbridge PCB.pdf

Parts (top): File:DualTbridge parts.pdf

EAGLE Files: File:DualTBridge eagle.zip

Built Devices

Dual TBridge Percussion device with piezo triggerpad to play the sounds by hand. The sounds can also be triggered by an external trigger signal. The piezo trigger pads have also trigger outputs to play external gear.

Demo Video

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