Pimp My Board!

The J-Mo Mk. II Headphone Amplifier


Download the schematic. Open in Eagle. Design a board layout. Win prizes!

The J-Mo Mk. II is a followup to the JFET-MOSFET headphone driver project. Like its predecessor, its a single-ended MOSFET source follower with a JFET input stage. The new circuit has an important addition, however: voltage gain of about 14 dB, thanks to a pnp transistor placed after JFET. This makes it a complete headphone amplifier, suitable for a wide range of headphone loads and input sources.

I've finished the circuit, but rather than make the circuit board layout myself I thought it would be both fun and instructive to outsource the job in the form of a little competition.

Which is why I want you to -

Pimp My Board!

How it works:

Download the Eagle .sch file. Create a board from the schematic. Arrange the parts and add traces. Make it nice. Make it look good. Submit your finished .brd and .sch files (preferably in a .zip archive) for your chance to win.

The instructions are pretty darned simple:

  • To enter, send a .zip archive containing both your finished .brd file and the .sch file that's linked to it by email to me, Richard Murdey (rjm003.geo@yahoo.com), no later than April 2, 2012.

There are few rules, as follows:

  • You can make the board single or double-sided, but it should be no larger than 10x8 cm.
  • You are allowed to edit and modify the schematic file.
  • Boards must pass a standard Eagle DRC (design rule check) without errors.
  • Schematic and board files must be consistent.

Entries will be mostly judged for how well they adhere to electrical "good practices" (proper ground layout, minimum trace length, reasonable separation of input, output and power traces, etc...), as well as neatness, aesthetics, innovation, and ease of access and flexibility. Compactness, while scoring positive, is not the main goal. I will select a list of finalists. The winning design will be chosen from the finalists by vote, at least that's the plan...

And what do I win? Are there prizes???

I will get a small production run of of the winning boards made, tagged "designed by [your initials]". The winner will get a pair of fully finished J-Mo Mk. II headphone amplifier boards, built by me. Runners up will get a pair of boards each.

Fine print: all submitted entries belong to me, though I give all the entrants the right to use their entries as they want, by giving the files to me you agree that I can use them as I want, too. Also, I reserve the right to make small changes to the winning design before fabrication, if last minute changes to circuit make that necessary.


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