Amplify 17Hz sine wave from a 555

[barry]

Re not caring too much about distortion......except that it defeats my purpose if the 'victims' can hear the additional harmonics on top of the 17Hz infrasound.

1% distortion is inaudible to most people, especially at 17Hz.

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You can modulate a 555 to produce a low (or high) freq PWM waveform which, when filtered will give a near sine wave, a simple C -R blocking ckt will then remove the DC to give a 0v reference for driving an amplifier. If you modulate with a triangle wave (17 Hz) and then filter you will get good enough.

From a 12V supply a simple darlington emitter follower could be used to buffer the filtered 555 output (with DC average level in place) and then feed to the speaker - with a blocking cap ( 220uF 63V) to prevent DC from entering the speaker.

This would suffice for the stated app.

Why would you create a triangle wave, convert it to PWM, and then filter it BACK to a triangle wave??? Talk about over-engineering.

 

[boylesg]

Mythbusters already proved that a "brown frequency" is a myth. They used far bigger speakers than yours to show that low frequency audio has no significant effect on the human body.

Myth Busted.....

Ah well I can think of plenty of other nasty tricks. E.G. Steel wool burnt with sulfur = FeS. Arduino controlled slow drip of HCl into the iron sulfide = H2S (rotten egg gas)

 

[d123]

Well my jail trash neighbor will make an ideal subject to practice the art on until I get it right! ;-)

The 'c' deserves it because has about several security cameras directly monitoring our property rather than his own!

So I feel entitled to have some electronics amusement at his health expense if I can pull it off!

Unrelated to electronics and hexreader's interesting remark, I feel I must say this - the joy of life is learning to free yourself of spite and negative actions. I would feel ashamed to write some of the things you repeatedly write here in a public space. Such words belong more to the darknet or juvenile delinquents than to a hobbyist who is a member of a delightfully healthy forum of people who help each other. I wouldn't help you with this project at all - your premise is wrong, I'm afraid, and no doubt illegal as well. In fact, over time, as I read your motives for some of your circuits, I do not think people like you should be allowed to tinker even with a LED if that is why you do electronics - you give the rest of us a bad name.

e.g. Food for thought, boylesg: When I get to your area, I'll test my homemade military-approved sonic and microwave radiation weapons* on you just because I do not approve of your attitude.

Can you see my point? Live by the sword... More importantly, two wrongs do not make a right, maybe you should focus on positive things like Tesla coils or helping your father with his hearing difficulties, for example.

* Obviously I do not possess such circuits and never would wish to - technology should enhance life, not harm it in any way at all.

(Moderators, I apologise for a non-circuit related answer that may seem harsh but I do feel my reply is quite justifiable.)

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...better yet, be an adult and sue your neighbour if they really direct cameras at your home - I understand that is an intrusion of privacy and intimacy/privacy is a legal right.

 

[KlausST]

Hi,

1% distortion is inaudible to most people, especially at 17Hz

I don't agree.
Esoecially with 17Hz.

My idea: most distortions are uneven harmonics.
17Hz is barely audible, but the 3rd harmonic, about 50Hz, is very well audible.
Thus maybe you don't hear an undistorted 17Hz,
But if distorted you may hear the distortion - only the distortion.

Klaus

 

[Easy peasy]

Why would you create a triangle wave, convert it to PWM, and then filter it BACK to a triangle wave??? Talk about over-engineering.

I tend to agree, but some people just want to use a 555, filtering a triangle (PWM or not) wave, will yield very close to a sine wave ( better than 5% in an ideal case ), it is easier in cktry to generate a triangle wave than a sine wave, and then filter the triangle, however for this app, even the square wave out of a 555 with an LC filter would yield an OK sine wave - but of reduced amplitude - the PWM approach allows a smaller filter and hence a retention of much of the amplitude ....

 

[barry]

Hi,


I don't agree.
Esoecially with 17Hz.

My idea: most distortions are uneven harmonics.
17Hz is barely audible, but the 3rd harmonic, about 50Hz, is very well audible.
Thus maybe you don't hear an undistorted 17Hz,
But if distorted you may hear the distortion - only the distortion.

Klaus

If you've only got 1% distortion the amplitude of the harmonics is going to be very low. OP's initial statement was that he wasn't concerned about distortion. Until OP puts some specific requirements out there, this is all academic.

 

[boylesg]

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...better yet, be an adult and sue your neighbour if they really direct cameras at your home - I understand that is an intrusion of privacy and intimacy/privacy is a legal right.

Would love to! But unfortunately I can't afford such civilized justice! Unfortunately in the west that is a luxury that only the wealthy can afford.