Circuit design help!

[Uncle Fester]

It's late here and I'm counting sheep as i type . . . . that being said there is no VR1 in your posted circuit! duh!

. .

No not my cricuits.

On the one you posted with the 555.
VR1 on the left of the timer IC is used to adjust the freqeuncy. You need to increase C1 on that ciruit to 4.7nF at least.

Just build that circuit 2x seperately and try the two piezo banks directly connected to them. Adjust VR1 so the sounders are at max volume at peak resonance and detune them a bit so it sounds even more annoying.

[cmangle]

"... and of course a total electronic maniac and earned money by building HiFi systems for my richer school buddies when I was 16."

I created/constructed/completed a set of stereo headsets(out of ear muffs) for a friend in '72 that did not look like cancerous mushrooms! It was off to the races from there! A "Dynaco Stereo Amp" kit was next! I can't think of one hobbyist young or middle aged today using parts from Radio Shack (or Dick Smith?)



I went into a BestBuy (nationwide stereo/computer/appliance chain store) the other week and a young know it all salesman was showing my friend the newest technology! A "Sound Bar" type audio system that uses two vacuum tubes (aka valves in Oz) for better sound quality!

Amazing this KID was trying to tell ME about vacuum tubes! I said "Ever hear of Marshall guitar amps?"

[Uncle Fester]

Interesting.
Although I spent many years in a music store fixing and modding valve amps (Marshalls only sound good when they were modded back then), I never understood why I would really want to use tubes for HiFi.
Don't get me wrong, I love the sound of valve amps but only to create sound, not to reproduce the finished created sound.
We have a store chain called JB HiFi and despite the name I fail to discover real HiFi there, so a couple of tubes might indeed improve the "sound"

Awesome that you built that amp as a kid (assuming you are my gen, younger teenager at that time).

[cmangle]

I remember around 8-9 years old opening up the family radio, Arvin 3586, in the kitchen(while my mom and dad were out for the evening) and seen all of the glowing tubes/valves inside. It looked like an urban city at night with little lit up skyscrapers. The colorful resistors and big round caps was the traffic traveling down the streets below, winding their way thru the tubes/valves and IF cans. Fascinated the living shit out of me!



Bad Boys Rape Our Young Girls But Violet Gives Willingly

[cmangle]

BTW, THAT radio was the "BOSE" of it's day!

The sound quality was phenomenal!

[Uncle Fester]

I remember around 12-13 years old opening up the family radio, Arvin 3586, in the kitchen(while my mom and dad were out for the evening) and seen all of the glowing tubes/valves inside. It looked like an urban city at night with little skyscrapers and colorful resistors and big round caps was the traffic traveling down the streets below winding their way thru the tubes/valves and IF cans. Fascinated the living shit out of me!



Bad Boys Rape Our Young Girls But Violet Gives Willingly

Woah, that is sure one way to remember ur Ohms.

I guess there is nothing to fascinate the young kids with a blob of epoxy on a tiny PCB or whatever there is inside a radio today.

But I have one success story to report. I got my teenager on the Arduino today. So I am most of the time giving him small projects to solve and mucking up interface devices, servos and stuff. I just found a Piezo buzzer like you have, wired it to plug into the Arduino and now gave him the task to make it produce talking sounds by producing residual low frequencies with bursts of the 4 kHz that it can actually only reproduce.

[Skepticist]

We must be fair to Dick Smith as he built up that business from nothing and it was always aimed at the hobbyist. Well until he sold the business to Woolworths and that's where it degenerated into what it is today, staffed by people who seem to think a phono cartridge is part of a cell phone and are only interested in selling big ticket items like cameras, TVs, phones, entertainment systems etc.

[cmangle]

BTW I edited out 12-13 years old to 8-9 years old, as it was a more accurate age! At 10 years old, I reverse fed a Lionel train transformer back into the house outlet which dimmed the lights for a second, blew up the train transformer, and tripped a circuit breaker in the panel in the basement!

They never left me alone in the house for quite a few years after that!

[cmangle]

I'll never forget the smell of burnt transformer windings . . . or the sting on my ass!

[lsemmens]

Never managed to blow any fuses in my youth, did try to become an earth for 240V when playing around with the TV Power Switch once. I've heard sparkies comment that they prefer to be zapped by 240V to telephone Ringer, but I'll take ringer any day!!!!

[cmangle]

"Woah, that is sure one way to remember ur Ohms."

Really? I thought that was the universal way to learn!

[Skepticist]

I learnt the colour code with a very similar jingle, one that might be considered racially inappropriate these days so I'm going to adopt this one now myself

[Uncle Fester]

It was simpler for me to identify the colour patterns of the standard E12 series.
Now with those 4 band blue metal film resistors you get these days I find my self counting the colours instead of immediately seeing the value, so annoying.
The contrast is bad on the blue background too. Many times I don't know if it is red or orange and I have to pull out the Ohm meter.

Didn't electrocute myself as a kid because I always knew where the GPO switch was(I don't know if you Yanks always have a switch on the power points) but I will refrain from explaining in detail the educational experiments I did with the exposed 240V terminals of my dismantled train transformer.
Today this kind of creativity is not required and I am more comfortable with our kids playing computer games, drawing manga and learning to code.

[bodeplot]

Hi Chris. Is your objective maximum sound pressure ?. If so, have you considered a few ultra loud car horns ?. The Stebel Nautilus comes to mind - 116dBA @ 2m and there are louder products. Scan the car/motorcycle forums and youtube for solutions. Don't quote me, but one user on a motorcycle forum a few years ago quoted a figure of about 120-125dBA from a horn at a distance of a few metres (can't remember exact figures). You would need double hearing protection to be anywhere near this. Just beware, some countries have legislative limits on sound pressure. So, just check on that in your country.

[cmangle]

Thanks bodeplot, I've ordered the components for using the piezo units. I was kinda thinking along the lines of a LRAD device like you see in the discovery channels Whale Wars series! Not so much as the sound pressure level as the freq/mod as well! I want it to be VERY directional so that it mostly(only) affects the immediate area!

[trash]

I felt the presence of evil here and had to check it out.
Woah! coool. I've got to get me one of those.

So a quick read of the wiki article and I've got the gist. Even a countermeasure.
So you want a very high gain audio antenna. Well good news, because audible frequencies and microwaves share the same wavelengths.
So any antenna that works well for microwave will make a fantastic speaker.

I notice the dude with the M16 and non-lethal weapons array also has a big set of hearing protection, probably because the sound that thing makes will resonate him a third testicle.

Given the shape of the "antenna" it's a good guess that it is some kind of phased array.
If I didn't know better I would say it was an array of tiny piezoelectric speakers behind an audio fresnel lens.
Though I'm curious to know what the radome is made off, or if the radio is actually the acoustic emitting surface.

If you were thinking of making your own non-lethal acoustic weapon, I might suggest you have all the pieces lying around home already.
An offset foxtel dish would be the first thing to grab. Next a high power piezo tweeter speaker from Jaycar. Rip off that LNC and mount the tweeter there.
Next find the highest power audio amplifier youcan get your grubby mitts on and build yourself a sinewave audio signal generator for about 2KHz.

Point and shoot! I'm getting "flash-forwards" right now of glass windows breaking over the next few weeks.

[lsemmens]

I'm with you there, Skepticist, I think that I'm too old to change now, so I may just have stay a little racist...

[Skepticist]

Old habits die the hardest they say

On the subject of disturbingly loud devices, the little piezo screamers used for alarms are not bad at it. The ones I've seen are small plastic horns that look like a tweeter and are fully self contained requiring only a supply like 12V and we use them on remote sites. They'd scare at least 1 life off a cat burglar if he's standing right under it when it goes off. They do give a few 'chirps' to warn you'd better enter the correct code or it's gonna get loud.

[cmangle]

trash you are absolutely correct. Inside that LRAD assembly there at least 30+ transducers arranged in such a way for MAXIMUM signal propagated in a narrow beamwidth. I'm looking to create two panels of 20 each on both sides of my entrance way, (crossfire effect?) When the perp stands in the PRIME area, I want to start his eyes spinning like a slot machine before he runs off screaming!
Skepticist, a loud noise would work from one of those horns alright, but I like the idea of the headache and nausea. I don't want this F##K coming back with a set of earmuffs! I want him to think there's something ALIEN in this "PHASER ARRAY" that sent him running!

[Skepticist]

I like it

Better practise the Dr Evil laugh