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How can I build an amplifying circuit to wire a vibrating motor to an alarm clock or cell phone? Answered

I will be going to college soon and have found out that my roommate gets shaken by loud noises, so I had to abandon my guitar-amp amplified phone alarm for a quieter alternative. I was referred to a vibrating alarm system that fits into pillows and runs on signal from music players and/or plain ol' alarm clock inputs, but those are waaay too expensive, and I prefer building my own over buying.

Here's the situation: I have a USB-powered vibrating massager that I got for free at some tech convention. Since it's USB-powered, I know it runs on 5 volts, which is more than my phone's 3.5 mm plug can deliver. How can I build an amplifier circuit that will boost the signal from my phone enough to run the motor?



If your phone outputs a +ve, you can use a transistor, or perhaps a relay. Either would be pretty easy.


 Think ye can help me out with some instructions?

I could, but you'd be better off with steve' I think, over to him.


So, you want to push out audio to trigger the 5V to the massager ? 

If you can get an output voltage >> 0.6 volts, then a little diode pump, followed by a single transistor amplifier should do what you want.


 Is there a way I can build the transistor amplifier? I was also told about those radioshack amplifiers. Would those work? and if so, how do I build one myself?

Looking in here for amplifiers based on the LM386 or LM380 is probably simpler for you than building a transistor amplifier.