ideas for a nice two tone "ding" sound

hax

New Member
#1
I am getting some Qprox chips which are capacitive sensing buttons. They can sit behind glass or plastic, enabling me to make a very aesthetically pleasing front panel.

http://www.qprox.com/background/rwa.php

They will connect to the picaxe for control.

But what I am after is a nice two tone or multiple tone "ding" sound which will signal when a button has been pressed.

I know the picaxe has the ability to send single tones, but wonder whether there is a dedicated chip to do what I want, or perhaps some sneaky code to make a picaxe sound like it is outputting two or more tones simultaneously.

Any ideas?
 

hippy

Technical Support
Staff member
#2
So many possibilities to experiment with ...

SOUND and fairly short tones played quickly in succession.

Multiple PICAXE's.

What about churning PWM frequencies/rates out of data Eeprom to do PWM modulation ? Or doing that programmatically ?

Melody generator chips.

DTMF generating chip, or two.

Control a door chime.

MIDI to a cheap music keyboard.

Solenoid controlled hammer and a cow bell :)
 
#4
Hi, what I experimented with was direct bit-banging to produce sound - I was just playing around and managed to get some wierd effects too that you can't get with 'sound' or 'tune' (such as frequency sweep like in a siren etc). http://www.picaxeforum.co.uk/showthread.php?t=5881 . (This approach also takes quite a bit of thought to get right)

However here you're talking polyphonic - which would be too much processing to bit-bang on one Picaxe I'd think. 2 * 08M would work. You could make the sound more pleasing by using simple low-pass filter(s).

I also experimented with adding a sound 'envelope' using a capacitor that really makes a difference to the realism of the sound. http://www.picaxeforum.co.uk/showthread.php?t=6602&highlight=metronome (since migration to new website ASCII art now gone a bit strange for some reason).

So I think that if it was a simple ding-dong thing then two 08Ms with envelope approach and low-pass filter might be good - although probably a lot of components compared to dedicated chip !
 
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#5
for what it is worth

Back in the dark ages we used a thing called a "twin tee oscillator" to get bell tones. A twin tee phase shifts the output of a single transistor so it drives itself with positive feedback - two resistors and two caps determine frequency. Output is on the collector and phase shift feedback network goes to the base - quick and easy with minimal parts.

Generally, it just sits there and oscillates with a pure sine wave.

To get a "bell" sound we added a resistor to ground to make the thing stop oscillating after a "trigger" on the base of the transistor. That created an envelope - attack and decay that sounded like a bell (of if the frequency was lower like a tom-tom or bass drum)

Should be easy enough to program the pwm frequency to output a 50% duty cycle square wave then use another output to do something like bias a transistor or mosfet to decay the amplitude over time with a simple RC network (or D/A if you are good at programming)


Take care
bob
 

hax

New Member
#6
Thanks guys,

I will look into Jeremy's ideas tonight and see what I come up with.


"Chime" is the word I was looking for. (so much easier to google what you want when you have the right word)

Looks like Siemens had a chip out in an 8 pin DIP package that was called a SAB0600-SIE THREE-TONE CHIME IC.


Proving very very hard to get my hands on one, not even a diagram. But an integrated picaxe solution (even two picaxes) would be better in the long run anyway.
 
#7
Now here's a tune

If you've got a spare few million dollars you could do this.

Do a google on "renault F1 warm up'. They use a F1 car to play "God Save The Queen"
 

KMoffett

Senior Member
#8
A chime circuit I've used for many years is a pulsed Sonalert type sounder. The attached schematic is based on a 555 IC, but could be easily adapted to a Picaxe. The key is the pulsed transistor and the large electrolytic cap across the sounder. In this case the asymmetric, astable 555 briefly turns the NPN transistor on with a short high-going pulse, rapidly charging the cap. With the transistor off, the sounder gives with a pleasing decaying tone. You can try this with just a cap and Sonalert, briefly hitting them with 12v. I suppose if you could find two sounders with different frequencies you could set up a Picaxe for a bing-bong chime.

Just another approach.

Ken
 

Attachments

#9
You should be able to come up with some interesting
chimes using 2 x Picaxe 08Ms using "Tunes" of various
lengths/timings, maybe even get DTMF going, you'll
need 2 chips though. PWM is better suited to siren
type sounds.
 

Tom2000

Senior Member
#11
Haxby,

Here's the envelope of a two-tone gong .wav file I brewed up some years ago, to accompany some freeware I wrote. It's a very pleasant sound. Perhaps you can use the envelope characteristics to help you synthesize your own tone. (The x axis is calibrated in seconds.)

I can't think of any practical way of reproducing this directly using a Picaxe or other simple hardware. Maybe one of those digital sound recording chips, but I've heard the quality isn't great. (No personal experience with them.)

If you'd like the file, follow this link, then scroll down to the bottom of the page until you find the "Download Alarm.wav" link.

Good luck!

Tom
 

Attachments

#12
I am getting some Qprox chips which are capacitive sensing buttons. They can sit behind glass or plastic, enabling me to make a very aesthetically pleasing front panel.

http://www.qprox.com/background/rwa.php

They will connect to the picaxe for control.

But what I am after is a nice two tone or multiple tone "ding" sound which will signal when a button has been pressed.

I know the picaxe has the ability to send single tones, but wonder whether there is a dedicated chip to do what I want, or perhaps some sneaky code to make a picaxe sound like it is outputting two or more tones simultaneously.

Any ideas?
Hi, no advice for your sound - sorry! But thanks for pointing out the Qantum button IC's. The multichannel ones look very cool, easy and cheap to implement on a PCB.

I hope you post the results and code from your project!

Cheers,
JohnO
 

hax

New Member
#13
Yeah, the capacitive buttons are all the rage at the moment as they are popping up in the MP3 consumer electronics market. But the benefit of using these types of buttons is huge for hobbyist applications, as you can truly get a professional finish on your product.

I am hoping to use www.customlasercutting.com to make up a professional looking front panel. They can etch into two-tone acrylic which will hopefully look absolutely fantastic with LED backlighting.

The two tone acrylic has a "piano black" top, but when etched, the white underneath shows up. Hopefully there is enough transparency in the plastic for a backlight to work.

Hence since going to the trouble of laser cutting a panel, and professionally having a PCB made, I wanted to be a perfectionist and I wanted to get the "ding" just right. I am now thinking that a simple "tick" might suffice. It only goes off when a button is pressed so I don't want a two tone sound every time i hit a button, tho one half of Tom2000's wav file would be good if I could re-play it with ease.

I think a "click" for each button is important when using these buttons as otherwise you dont get much of an indication that it has registered your touch.
 
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