# Making a transducer vibrate with changing amplitude according to an analog pattern

Discussion in 'The Projects Forum' started by c3real, Feb 16, 2012.

1. ### c3real Thread Starter New Member

Feb 16, 2012
4
0
As the title suggests, I am trying to make a vibrational transducer vibrate with changing amplitude according to an analog pattern at fixed frequency. I have been attempting to learn this for more than a month now and I am still utterly confused.

The closest I came by can be found http://bdml.stanford.edu/twiki/bin/view/Haptics/VibrationImplementation.html
It gives details of the op-amp circuit that connects to the transducer. But whatever comes before it, the DAC circuit and whatnot, I have no idea how to accomplish.

If the analog signal (amplitude VS time) I want the transducer to mimic is analog form, why did his circuit have a DAC circuit in the first place? Isn't it analog already? And I can't figure out how the binary numbers come into play.

I know my project sounds really simple but it someone can give me some directions and explain some of the things I need to do it would be awesome!!!

2. ### Experimentonomen Member

Feb 16, 2011
331
46
What it sounds like you want is a voltage controlled amplifier that changes output amplitude from zero to full based on a control voltage.

3. ### c3real Thread Starter New Member

Feb 16, 2012
4
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Yes, exactly. The range of the vibrating element is from 0V to 5V.
On the other hand, I have this analog time sequence that I want to input into this element to have it vibrate proportionately.

Why do I have to put this analog data into binary, and then feed it into a DAC circuit, before putting it through the op-amp?

4. ### Experimentonomen Member

Feb 16, 2011
331
46
You don't. He's prolly using a digital source for the wave signal such as a sine table stored in a eeprom or such.

5. ### c3real Thread Starter New Member

Feb 16, 2012
4
0
oh .... then is there a simpler way to do it. for someone like me without an electrical background ...
How would I translate the wave signal that I have on the computer, into the vibrating element?

6. ### Experimentonomen Member

Feb 16, 2011
331
46
Just build an analog oscillator of the desired wave shape, sine, square or triangle, there are tons of schematics on the net for each type.

7. ### c3real Thread Starter New Member

Feb 16, 2012
4
0
I will try to figure out what that means. thanks.....