Q: Voltage Amplifier I have a 3.7v battery as a power source. I want to make a circuit in which I can regulate the voltage between the ranges of 2.5-5v. I was able to build a circuit with a LM317. It allowed me to trim the voltage down to 2v. 
The problem I'm facing is how do I amplify the voltage up to 5v? The solution's I've seen suggest I use an OP-amp. But, the max I was able to get out of that was 3.7v because I only have a 3.7v power source. I believe it's called clipping or something along the lines.  

A: As mentioned in one comment you probably look for a Boost/Buck converter. The Boost-Converter can "increase" your voltage while the Buck-Converter can "reduce" your voltage. Both can do that in a fairly efficient way (if you don't care about efficiency you can do it much simpler).
Here is a list for converters just from one vendor:
http://www.ti.com/lsds/ti/power-management/dc-dc-switching-regulator-overview.page
And here just some ideas (but there are many more) to do it yourself:
http://www.ti.com/lit/an/slyt584/slyt584.pdf
