Controling 4 vibration cells with a attiny85 chip

Using Arduino Project Guidance
#1

Hi,

I'm trying to control 4 vibration cells Individually which rate at 2-3.6V. After some research I see it's safer to use a transistor so the motor isn't on the IC's pin directly and also to have diodes too as the motor can do weird stuff to the current or something, anyway..

I was wondering, does this circuit look feasible?

I'm a noobie a this stuff so probably have it wrong and really would like an experts eye before I start blowing things up XD

Many many thanks in advance

#2

Hi 7immy,

I'm not an ATTiny expert, so I won't comment on that aspect of your circuit, but you should put resistors between your IO pins and the transistor bases (1k should work) to limit the control current to them.

Also, google flyback diodes to see how to connect them up ('backwards' across your motor).

Pat

#3

You use the transistors as emitter-followers. That's fine if you add the flyback diodes, but the voltage over the motors will be 0.6V lower. The diode in the circuit will cause another voltage drop of 0.6V. So the vibration cells will get only 1.8 Volt.

You could use the vibration cells at the collector. Look at the pictures for "Connect a Relay". The relay would be a vibration cell. http://arduino.cc/forum/index.php/topic,154549.0.html

Are you sure the vibration cells are motors with a disc ? Some are resonators. These are the good ones, http://www.adafruit.com/products/1201

#4

Are these vibration sensors, or vibration creators like a cellphone has ?

#5

Thanks for your help guys, much appreciated :) I've revised my circuit which now looks more like this:

These are the vibration cells I'm using https://www.sparkfun.com/datasheets/Robotics/310-101_datasheet.pdf which look very simular if not the same as the link you posted http://www.adafruit.com/products/1201.

Interestingly though the adafruit link says its safe enough to use them directly on an Arduino pin with a 100 ohm resister. Do you think thats safe with an attiny too? It would save a lot of components!

Thanks again :)

#6

Your circuit is okay. You could add a small 100nF over the ATtiny85 to decouple the 3V battery.

The ATtiny85 can only deliver 20mA (I think so, but I'm not sure). So for the ATtiny85 you would need a higher value. Using a resistor with 100 ohm will also lower the voltage over the motor.

#7