HOW TO MAKE CAPACITIVE TOUCH OPERATED TONE GENERATION WITH A MICROCONTROLLER?

[nishy555]

Hello… Im a mechanical engineer & product designer from india.....Im trying to make a project....for that I need TO produce continuous tone at 6 different frequencies (between 17000hz to20000hz) or (between 20000hz to 26000hz) from single sounder/buzzer. And these 6 frequencies should be operated with 6 capacitive touch points. When ever I touch one of these buttons specific frequency should produce….Can anybody please clear my doubts….

1) Is using microcontroller is my best choice? (Presently im using 555 timers in astable mode to produce specific frequency with 6 Toggle switches.

2) Is it possible to produce a continuous tone at specific frequency with line of code using microcontroller? Im working around 20k frequency….Most of the micro controllers working speed is several Megahertz does this produce tone brakes or any other problem?

3) How many pins & bits microcontroller im going to need?

4) What is the smallest & least power consuming microcontroller  I can use?

[matseng]

If you can't write software for microcontrollers (code in C) or don't know anyone that does my guess is that a microcontroller is not your best option.

For touch operation of your existing 555-circuit you might want to use something like this.

[matseng]

But if you want to use a microcontroller a 8-pin ATtiny13 (or similar device) would most likely be enough. 

One tone output pin
Three+two pins for capacitive sensing of six buttons configured in a 2x3 matrix
Two pins for power

Running at 1MHz it only uses 190 uA.

In addition to the microcontroller you need a transistor to up the speaker volume a bit, and some caps+resistors.

[nishy555]

If you can't write software or don't know anyone that does my guess is that a microcontroller is not your best option.

For touch operation of your existing 555-circuit you might want to use something like this.

Thanks for your reply....  For now im using 555 timer with 6 resistors along with 6 toggle switches.... When ever switch is pressed that particular resistor comes into circuit and produces specific frequency depending upon resistance value. I dont know how can i add transistor based touch switch at the place of normal toggle switches.....(Im afraid small flow of current that exist through transistor may produce noise/unwanted frequencies while it is unused) ....

[Moondeck]

Use one of those capacitive switch ICs from Microchip, they are dirt cheap and have simple "boolean" interface    http://www.microchip.com/wwwproducts/Devices.aspx?product=MTCH108
Microchip is love, Microchip is life

[Mr Smiley]

Have a look at this guy

Julian Ilett

https://www.youtube.com/user/julius256/videos

He's recently been playing with touch sensors and sound generation, one of his recent projects is a "Penny Organ"

 

[nishy555]

Use one of those capacitive switch ICs from Microchip, they are dirt cheap and have simple "boolean" interface    http://www.microchip.com/wwwproducts/Devices.aspx?product=MTCH108
Microchip is love, Microchip is life

Thanks a lot for your help .... basically im a product designer(http://www.nishanth.me/home.html) i hardly know about electronics ......  Can you imagine how much time it will take to make this for a beginner?? Can i find any related tutorials? or any related projects on web? or it is it better to go for a freelancer? How much should i offer for a freelancer?(I really don't know how hard is this thing to make) i wnat to make this within a month....Please suggest me anything help full....

[slateraptor]

I'm curious how you intend to validate implementation considering 17kHz is pragmatic threshold of human hearing for all but a certainly small percentage of the population, let alone 26kHz...food for thought.

However way you decide, recommend verifying that the selected sounder/buzzer's frequency response is within range.

[Moondeck]

Use one of those capacitive switch ICs from Microchip, they are dirt cheap and have simple "boolean" interface    http://www.microchip.com/wwwproducts/Devices.aspx?product=MTCH108
Microchip is love, Microchip is life

Thanks a lot for your help .... basically im a product designer(http://www.nishanth.me/home.html) i hardly know about electronics ......  Can you imagine how much time it will take to make this for a beginner?? Can i find any related tutorials? or any related projects on web? or it is it better to go for a freelancer? How much should i offer for a freelancer?(I really don't know how hard is this thing to make) i wnat to make this within a month....Please suggest me anything help full....

First of all, what do you want to make?
Second, on your site you say you are an engineer?