Hi
I found this drawing to build a "One-IC two-tones Siren" http://www.redcircuits.com/Page5.htm on several sites around the web. I ordered the parts but when I looked closer I see that R8s value is 3M3.

At first I thought this a typo and the value most likely 3.3M but started thinking that would be an open circuit.

I'm just wondering if someone could look at this and help me with this value?

Thanks

 

CD4093B devices are 4000-series CMOS logic circuits. These circuits have very high input impedances; a 3.3Meg resistor won't act as an open.

 

Thanks, I'll run out and get a 3.3M tomorrow and try it on my solderless breadboard.