Amplifying the output from a surface mounted chip

Hi, I am trying to amplify the output from one of the data pins of decoder like this one http://www.linxtechnologies.com/Documents/LICAL-DEC-MS001_Data_Guide.pdf to drive a vibration motor which pulls the current up to 130mA at 3v(resistance : 23ohm). The maximum source current from the decoder is 25mA. Could you advise me how can I amplify the decoder's output to drive that motor?

Could you advise me how can I amplify the decoder's output to drive that motor?

Pretty simple. You have a resistor, maybe 1K ohms, wired from your device's output pin to the base connection of a NPN transistor. Wire the emitter of the transistor to ground. The collector of the transistor wires to the motor and the other end of the motor wires to +3vdc suppy voltage. A common 2N2222A transistor is rated to 800ma of current so should work fine for your little motor.

Lefty

Lefty

Hi, thank you very much. Could you look at this drawing? I was wondering whether I did it ok. http://www.flickr.com/photos/34955071@N02/4104575494/sizes/o/

I was wondering whether I did it ok.

Yep, looks good. Some recommend wiring a simple diode (1N4001) directly across the motor terminals (cathode to positive terminal) to help prevent noise and spikes. For these small motors it's probably not as important as with the larger ones, but can't hurt and diodes are cheap.

Now with your software you have the option of using digital output commands to turn the motor on or off or using the analogWrite commands on the PWM pins to run the motor from off to 100% speed.

Good luck;

Lefty

Thank you so much. It's very helpful. I appreicate that.

I have a question for 2N2222. I don't know which pin is which. Could you let know me? http://eleparts.co.kr/epdf/TR/2N2222.pdf

Looking at the bottom view of the transistor:

http://www.atariarchives.org/ecp/figure8-1.gif

Lefty

Thanks a lot. :slight_smile: