I've been using the Boss TU-12H chromatic tuner for about four years and I have found that while it isn't the most efficient tuner in the world, it definitely does the job pretty well. It has a 1/4 inch input so you can plug your instrument into it and tune it. Unfortunately it doesn't have an output so you can't run your signal through this and put it into an amp, but I guess it isn't really made for that. The best part about the TU-12H is that it has a few different modes that will allow you to tune your instrument in a few different ways depending on the situation you are in. In addition to tuning based on plugging your instrument into this, you can also play any note to tune to on the TU-12H as it has a digital processor on it. The metering is big and clear and is definitely helpful when tuning your instrument with this so you can see exactly how close or far you are from the note you are trying to tune to. The price of the Boss TU-12H is really cheap, especially if you can get one used. Overall, I would recommend this tuner for acoustic guitar players and for electric guitar players I would really advise that you get the Boss TU-2 chromatic tuner as I believe it is the best tuner out there. The Boss TU-12H will do the job well, but is a bit old looking and isn't great for playing shows with at all. It is more for the guy or girl sitting in their room playing their acoustic guitar or for use in the studio. It really just depends on what you would like to do with the pedal. In the end, it is a perfectly capable tuner at a cheap price brought to you by an extremely reliable company.
I possde this marvel of precision about 2 years and the only criticism one could tell him the price, it may be to be a little too prcis (There's of time or the needle really so hard to stabilize this thing captures all the nuances color!).
I use the 10-year TU12H,
jaime what most: the display has very good needle + led to settle an instrument (guitar being I use it to pay my harmonics)
black dot: not visible enough to be used "live" (I use a TU2 in this case)
very good value for money
If I had to choose: I repprendrais for use regulating and company but I would opt for a TU2 live only for use (in fact they are really complementary so ....)