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555 Timer Tone Generator. Which capacitor should I use, and where do I add the power source? Please help!? Answered

I'm wanting to make a tone generator with a 555 timer that is a frequency humans can't hear. I'm going to follow this schematic. My R1 (potentiometer) will be 10k. R2 will be 33k. C1 will be .001mF. What should capacitor 2 be? And would the resistors i mentioned work for making a tone within the 17-20 Khz range? Also, how and where would I attach the power source? I'm thinking about using a 9 volt battery. Or would something else work better? I want it to be able to run for several hours straight. Thanks!

Thank You!

EDIT: Also, I want it to be a constant tone, not a beap.
If I have this completely off please let me know and guide me in the right direction. I'm new to this and would greatly appreciate any advice you may have.


Pranjal Joshi

7 years ago

1st pin - gnd (-ve of battery)
8th pin - vcc (+ve of battery)

try to use 10nF capacitor bt if u want that it wil produce sound even aftr disconnecting battery then use 1000nF capacitor which stores charge n ur buzzer ring upro 40 sec even battery is disconnected...


7 years ago

Hate to burst your bat scaring ideas. But normal audio speakers are not made to produce sound above human peak range of hearing.



7 years ago

That's not a very well drawn schematic, is it?

Pin one is ground or negative and pin 8 is positive so you can connect positive to any wire that is connected to pin 8.

Look at the connection diagram in this pdf on the second page.  It tells you what each pin is.  You should always consult the chip data if you have questions.  They will teach you much about using the chips that you might miss otherwise.

As to what size cap to use, you may have to use trial and error.  I've had no luck calculating before hand what size to use to get a certain range of freq.


Answer 7 years ago

Hey, http://forum.allaboutcircuits.com/showthread.php?t=62071&page=2 thats the discussion i've had on another forum with some people. If you could read it and then come back and reply again I'd appreciate it! Thanks!


7 years ago

a 555 circuit won't draw a tonne of power but still I always advise to avoid 9v batteries because they are crap. Pick up a 2, 3, or 4 AA or AAA holder with power switch for a few bucks.

As for your frequency, just use an online calculator to decide what frequency range you want.