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# Simple sound effects circuits (LM3909)

2015-01-10 09:53
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This article describes the Simple sound effects circuits (LM3909). The principle is very simple, very practical. The circuit components can help you understand better grasp this principle. For example, in this circuit, you can go to find and buy these components: LM3909.

This is Sound effects two tone circuit, which generally abound measure various both of kinds use IC frequency origin oruse the transistor. The sound will that is proportionate big depend on the value of R and C. For this circuit is will building sound of pale long tail or clock ancient sound.
The work of the circuit, when , build the circuit suits power supply have current change R1,VR1 go to charge at C1, enough C1 have volt fall straddle arrive at 0.7V make Q1 begin the work bears fruit to make Q2 work with LED1. Then stick bright and a loudspeaker utters.
From that time C1 begin discharge and change a pin B go out a pin E of Q1 when charge be finished Q1,Q2 stop work. The LED1 not bright and a loudspeaker doesn’t be born the sound.

From that time C1 begin charge again the frequency will come out to depend on the time in something charge and discharge of C1. If C1 charge and discharge get fast the frequency will have that tall. If C1 pick and discharge get slow the frequency will have that low. Which in this circuit has will VR1 wait for control the speed in something charge of C1. If VR1 be valuable very C1 will charge get slow. If VR1 be valuable a little C1 can work fast.

## Mini Trombone Sound generator by LM3909

This be Mini Trombone Sound generator circuit. By using integrated circuit the number LM3909 of NS. In using loudspeaker 25 Ohm sizes work by use voltage from AA 1.5V battery. In sound occurrence that resemble with trombone.
It have the work depends on the principle uses voltage, which the generator by the occurrence Resonance of sound coil of a loudspeaker is feeding gets back to the way adds to give with integrated that circuit was set up in large-sized box,which there is the capacity about 64 inch cubic which one side of a box has can to move in and out resemble a cylinder a position of a piston.
The work of switch press will cause the tone of voice that resemble very integrated loudspeaker circuit and battery touch set up on a piston , which there are 5 size inch pipes. For be born air push reaches and go out while a piston moves by don’t affect to build the frequency Resonance. The frequency of origin frequency circuit will begin to equal to the frequency Resonance of a box.

## Peal from the transistor

The work of the circuit,which the Tone audio generatorcircuit will distribute to is 2 part, be first part is will the part frequency generator modern by using transistor 2 pcs. build be frequency generator circuit astable multi vibrator which Q1 and Q2 work alternate. When Q1 work LED1 stick lay part C2 begin charge with regard to Q1 and Q2 work alternate will cause the frequency goes up and when C2 charge the full have current flow go to at a pin B of Q2 make Q2 bias LED1 not bright. If Q2 work have current flow through R4 change a pin C go to still a pin E of Q2 down ground make have current flow through R5, R6 go to bias pin B of Q3 make Q3 work PZ1 as a result oud by have C1 will charge full until and when Q2 stop work cause Q3 stop work with, but have voltage from C3 discharge give PZ1 make the loud sound quietly, diminish resemble bell sound.