Hi! Could anyone help with how to calculate Hz in a siren system? Here is a picture of the system:


The Hz of the first astable 555 circuit is supposed to be 1 Hz and the other system is supposed to be 1kHz.

I used this formula:



(the one on the top called "to calculate frequency")

I tried to put 3.3u as the c value and 0.01u (converted to Farad of course). I also tried to put both in series and in parallel, but i couldnt get 1Hz!

What am i doing wrong here?

All help much appreciated, and thanks for your time!

Moderators note: replaced unwanted links with uploaded pictures

 

481 Hz central frequency, it will sweep up and down at 1hz rate...

 

Could you explain that a bit? Sorry i'm quite new to this

 

Hi! Could anyone help with how to calculate Hz in a siren system? Here is a picture of the system: http://imgur.com/a/N9E6Q

The Hz of the first astable 555 circuit is supposed to be 1 Hz and the other system is supposed to be 1kHz.

I used this formula: http://imgur.com/a/SZipc (the one on the top called "to calculate frequency")

I tried to put 3.3u as the c value and 0.01u (converted to Farad of course). I also tried to put both in series and in parallel, but i couldnt get 1Hz!

What am i doing wrong here?

All help much appreciated, and thanks for your time!

Please provide a 'clean' link! -- Speaking for myself, I have no desire to join another site nor expose myself to their spam, etc. merely to view your images/'outside' post{s}! Advice and instruction are offered gratis here - inasmuch as basal courtesy (on your part) costs nothing!

With regards
HP

 

Hello,

@Hypatia's Protege ,
I always use adblock to block unwanted adds.
I have replaced the links with uploaded pictures.

Bertus

 

@SainAralor
For the benefit of other readers I've done your work and posted the image (below):

Could you explain that a bit? Sorry i'm quite new to this

What would you have us clarify? The second stage's 'control voltage' input (and, hence, output frequency) is 'swept' by the first stage...

With regards
HP

 

Hello,

@Hypatia's Protege ,
I always use adblock to block unwanted adds.
I have replaced the links with uploaded pictures.

Bertus

Thanks @bertus -- I made my second response prior to seeing your amendment to the OP

Best regards
HP

 

The second stage's 'control voltage' input (and, hence, output frequency) is 'swept' by the first stage...

HP that brings back memories for me cuz when I was a kid I used switched DC levels on pin 5 of astable 555 for FSK generator and it ran error free at 19.2k baud with just ps osc cap but I had ten pole RC LPF on output! Now everyone is probably saying I was super industrial strength stupid for not just using XR2206 with onchip digital keying circuit and sine output! So I was just having fun building RS232 to FSK translator w/o special chips

 

Could you explain that a bit? Sorry i'm quite new to this

The main frequency astable is centerd on 481hz, without the 1 hz astable it would make a continuous tone, the second astable is clocking at 1 hz and increases and decreases the 481hz, so it may sweep from 400hzto 600hz due to the control voltage on pin5.

 

Now everyone is probably saying I was super industrial strength stupid for not just using XR2206

Go figure!

TTFN
HP

 

blaah, blah , . . .