Simple Electronic clock sound using IC4011

The sound of insects such as crickets, cicadas, resulting from flutter briefly. We can use a multivibrator to connects as sound generator circuit to imitate these insects sound.
Some electronic clock alarm tone also sounds similar to these insects. As Figure 1 is simple clock alarm sound generator that can assemble on a breadboard right away.
Working of circuits
As Figure 1 The circuit consists of two astable multivibrator, firstly include both gate IC1c and IC1d are used generate low frequency as the sounds of insect wings. A second also include with both gate IC1a and IC1b same simple tone generator using CD4011 which is higher frequency than first. And they are used to set rhythm interval of sound.
The output of multivibrator 2 (pin 4 of gate I2) will be controlled by the first astable multivibrator which generates the low frequency as the tone burst signal characteristics.

Figure 1
We control them switch continuously with oscillation and stop oscillation with low frequency about 5 Hz.
In this case we use signal “1” and “0” alternately. If state “1” will make the oscillation, but is “0” will stop the oscillation.
The Devices R and C astable multivibrator as circuit will get tone frequency about 600 Hz and Strokes will interval is about 0.2 Second. Please try modifying these to change the R and C melodic sound to listen up.
Components list
IC1____CD4011 Quad nand gate CMOS IC____= 1 pcs.
Q1____BC337____0.8A 40V NPN transistor______= 1 pcs.
T1____Small signal transformer________________ = 1 pcs.
R1____100K___1/4 watts 5%__________________ = 1 pcs.
R2,R4____1M______”_______”________________ = 2 pcs.
R3,R5____68K_____”_______”__________________= 2 pcs.
R6______5.6K_____”_______”__________________= 1 pcs.
C1______1uF 50V Ceramic capacitors_________ = 1 pcs.
C2_____0.0015 uF______”______”______________ = 1 pcs.
C3______0.01 uF_______”______”______________ = 1 pcs.
Speaker 8 ohms._____________________________ = 1 pcs.
How to builds
We experiment the circuit on a breadboard or assemble all components on Perforated board as Figure 2

The previous circuit low volume since piezo speaker which use high impedance so use low current consumption, but it low volume.
This circuit I need loud volume better the previous circuit. So use normal speaker 8 ohms 0.25 watt. But we cannot connect it to IC’s output directly.
We so use a small audio transformer to prevents the very low resistance of the speaker (8 ohms) from loading down the circuit and possibly even stopping its oscillation.
And there is transistor-BC337 to drive transformer, cause this circuit have very loud volume than one.
Switch S1 is used for turn ON/OFF tone generator.
Power supply voltage can use during 4.5V to 13V, This reduce the supply voltage and lowers the volume. As video below.