A sound of ripples
Electronic
LM324, BA546

This project invites you to a beach. You can expect that the murmur of surf relaxes you.

After you finish wiring, turn power ON. You hear from the speaker a sound of ripples washing the beach.

The kit at your bedside would put you to a quick sleep.

Have a look at the schematic diagram. The circuit is the same you used before. The oscillators U1A and Q1 generate white noise. 

The white noise is amplified by U1B and U1C to produce a sound (noise) of wave. U1D is an oscillator of a square wave having a long interval. It determines the intervals at which the surf rolls in.

The square wave becomes dull as it goes through R15, R16, and C8 before entering the emitter follower Q2. The output from Q2 goes to the VCA (voltage-controlled amplifier) comprised of Q3 - Q6. On the other hand, the sound of wave produced at U1C also enters the VCA.

This wave sound follows the level of the dull waveform sent from Q2, making itself gradually louder and quieter to generate the murmur of ripples. This sound is amplified by the power amplifier U2 and output from the speaker.

You may wish to change the values of components to change the intervals and levels of the wave. You can figure out what components to change.

Bill Of Materials For A sound of ripples.DSN
Design Title : A sound of ripples.DSN Author : <NONE> Revision : <NONE> Design Created : 17 juin 2019 Design Last Modified : 23 juin 2019 Total Parts In Design : 57
27 Resistors
	Quantity:		References		Value		Order Code
	4		R1-R4		22k
	2		R5, R9		1M
	4		R6, R8, R12, R13		100k
	1		R7		470k
	2		R10, R11		220k
	2		R14, R15		47k
	2		R16, R18		33k
	1		R17		150k
	1		R19		10k
	4		R20, R21, R24, R25		4K7
	2		R22, R23		1k
	1		R26		470
	1		R27		270
16 Capacitors
	Quantity:		References		Value		Order Code
	1		C1		470pF
	2		C2, C3		0.1uF
	2		C4, C10		1uF		Digikey 399-3058-2-ND
	3		C5, C6, C12		0.001uF
	2		C7, C8		33u		Digikey 399-3058-2-ND
	1		C9		0.047uF
	1		C11		3.3uF		Digikey 399-3058-2-ND
	2		C13, C14		10uF		Digikey 399-3058-2-ND
	1		C15		470uF		Digikey 399-3058-2-ND
	1		C16		100uF		Digikey 399-3058-2-ND
1 Integrated Circuits
	Quantity:		References		Value		Order Code
	1		U1		LM324
6 Transistors
	Quantity:		References		Value		Order Code
	2		Q1, Q3		2SA933
	4		Q2, Q4-Q6		2SC945
3 Diodes
	Quantity:		References		Value		Order Code
	3		D1-D3		1N4148
4 Miscellaneous
	Quantity:		References		Value		Order Code
	2		+, -		4.5V
	1		LS1		SPEAKER
	1		ON		OFF