Ocean Sound Generator

The Elektor Surf Synthesizer convincingly imitates the sound of breaking waves. It is based on a circuit published in the 1972 summer edition of Elektor to celebrate the Summer Olympics held that year in Munich, Germany. The Surf Synthesizer can be considered a real analog music synthesizer, as it follows the paradigm of voltage-controlled subtractive sound synthesis made popular by Robert Moog and friends (remember the Elektor Formant?). Instead of a VCO (voltage-controlled oscillator), it has a noise generator as a sound source. A VCF (voltage-controlled filter) and a VCA (voltage-controlled amplifier) modulated by three LFOs (low-frequency oscillators) shape the sound of the waves.

The Surf Synthesizer comes as an easy-to-build kit using only through-hole components. The kit contains all the required parts, including a stylish wooden stand. First mount all the parts on the front side (showing the schematic). Terminate by mounting the battery holder on the backside (showing the circuit description).

The use of headphones (not included) is recommended for obtaining the best sound quality.

A 9 V (PP3) battery (not included) powers the Surf Synthesizer.

Component List

Resistors (5%, 0.25 W)

• R30 = 100 Ω
• R1 = 470 Ω
• R39 = 560 Ω
• R36 = 680 Ω
• R26 = 1 kΩ
• R35 = 2.2 kΩ
• R18 = 4.7 kΩ
• R2, R5, R6, R9, R10, R13 = 6.8 kΩ
• R16, R37, R38 = 10 kΩ
• R14, R24 = 22 kΩ
• R15 = 33 kΩ
• R7, R20 = 39 kΩ
• R11, R19, R21, R28 = 47 kΩ
• R4, R12, R17, R23, R25, R31, R32, R33, R34 = 68 kΩ
• R22 = 100 kΩ
• R8 = 180 kΩ
• R3 = 270 kΩ
• R29 = 680 kΩ
• R27 = 1 MΩ
• P1, P2 = 50 kΩ trimmer

Capacitors

• C13 = 4.7 nF
• C11 = 47 nF
• C12 = 100 nF
• C10 = 220 nF
• C9, C14, C15, C17, C19 = 10 µF, 16 V, 2 mm pitch
• C2, C3, C4, C5, C6, C7 = 47 µF, 16 V, 2 mm pitch
• C1, C8, C16, C18 = 100 µF, 16 V, 2.5 mm pitch

Semiconductors

• D1, D2 = 1N4148
• D3 = BAT48
• T1, T2, T3, T4, T5, T6, T7, T8, T9, T10 = BC547C

Divers

• BAT1 = PP3 9 V battery holder (battery not included)
• K1 = speaker 8 Ω, 200 mW
• S1 = slide switch
• Elektor PCB 240095-1
• Wooden stand

Specifications