# Single tone buzzer with 555 timer

#### PsySc0rpi0n

Joined Mar 4, 2014
1,446
You can but I am not sure it meets the intention of the teacher's assignment. It is my guess that the teacher wants the 555 to generate an audible tone (astable mode). If you use a buzzer instead, like you have so far, what is the point of the 555.

Think about it, your interpretation is better titled, "self-turning off buzzer" than your title on this thread, "single tone buzzer with 555 timer".
So, as far as I understand is, to use a buzzer, I just need some current... So, no need of the 555, right?

Ok, so to the 555 generate an audible tone (astable mode), what can I use in LTSpice?

Is your project is to emit a single continuous annoying tone?

Your ears with thank you for that switch.
The fisrt part of this problem, yes... Then I need to build another circuit that emit an "american siren" (whatever that is), but for now, yes, it's a single tone but using the 555!

#### ericgibbs

Joined Jan 29, 2010
10,758
Ok, so to the 555 generate an audible tone (astable mode), what can I use in LTSpice?
hi,
This is one option.
I would use around 3kHz as thats the most ear sensitive frequency.
If you build the sim circuit let it run for one second, replay in Windows media.

E

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#### PsySc0rpi0n

Joined Mar 4, 2014
1,446
hi,
This is one option.
I would use around 3kHz as thats the most ear sensitive frequency.
If you build the sim circuit let it run for one second, replay in Windows media.

E

Wow, that's great...

But you need to explain the role of those 2 caps connected from rail to rail... Are just to smooth voltage within rails? If so, why 2 and not only one?

Should I use a transient analysis, right? For like 2 seconds??? Is it enough?

As far as I can see, that is an astable mode for Duty Cycles greater than 50%, right?
So I tried to calculate the tON and tOFF times:

tON = ln (2)x(15k + 15k)x10n = 208 μs
tOFF = ln (2)x15kx10n =104 μs

frequency = (1/ln (2))/((15k+2x15k)x10n) = 3.2kHz

#### ericgibbs

Joined Jan 29, 2010
10,758
But you need to explain the role of those 2 caps connected from rail to rail... Are just to smooth voltage within rails? If so, why 2 and not only one?
hi Psy.
Those two capacitors are for decoupling the power supply, it is good practice to fit decoupling on actual hardware.
The 100uF will decouple/smooth out any high current demands made by the circuit, the 100uF will give better decoupling at the higher frequencies.
Look up on the web, the performance of different capacitor construction.

You can choose 2 secs, if you wish, all that means is that Windows media sound will last for 2 seconds before it repeats.

E

BTW:
LTS can also READ wave files, so its possible to feed in a signal to a simulation you design.