Built a simple Function Generator with Frequency Counter over the last couple of nights. It’s pretty basic — 0-~500kHz, 0-12V, Sine or Triangular waves — but good enough for my test needs. The frequency counter is basically an Arduino repackaged to feed the attached LCD. The counter isn’t super accurate, but is within 1% of what my multimeter says.
The kit has a fairly high voltage requirement for DC (>= 15V), but this was solved by a quick trip to Active Surplus. $11 bought me a 15V power supply (which delivers around 19V open circuit) and the right kind of barrel jack.
(Talking of neater meters, I didn’t know mine could support the Bluetooth Adaptor reviewed here. Dad’s old Avo couldn’t do that!)