Help!!

[wyl86]

I need to build a simple siren circuit producing double tones with 74HC14. But I only manage to get a single tone.. How should I fix it?

actually it is a very simple alarm circuit.. tts y i only gt 1 tone.. for the IC a wire from pin 1 is connected to pin 4, den a capacitor connected to pin 2 n 3, resistor to pin 3 n 4. bt hw shld i get 2 tones?

 

[ronsimpson]

Please post what you have now.

 

[ronsimpson]

I have not tried this.
Inverter must be 74HC14.
RC1 is slow osc. 1 cycle/second.
RC2 is tone 1
RC3 is tone 2
D1,2 turns off OSC2 or OSC3
D3,4,R4 add two signals.

 

[wyl86]

what if I'm using a 3V batt to operate is it alright?

 

[Krumlink]

Yup. The HC series IC can run on 2-6v.

 

[wyl86]

Thanks!!

 

[wyl86]

for the diode what should i use?

thks!!