Low Frequency Continuity Beep for Fluke 8060A

[Dave Wise]

I love my 8060A handheld DMM's instant continuity beep, except I can't hear it.  It's approximately 2700Hz but I have a hearing loss that notches it out.  I modified my 8060A to output a lower frequency that I can hear.

The mod is a tiny daughterboard that mounts on the main board in place of Q6, a 2N3904 that drives piezo sounder LS1.  We need one flying wire to pick up +5.2V Vdd to power the microcontroller.

[Dave Wise]

I just noticed that attach failed and only the pictures got uploaded.  Here comes schematic, PCB layout, program, and assembly instructions.

I figured out a trick for extending the frequency range on small PIC microcontrollers whose Numerically Controlled Oscillator has an undersize (16 bits) Increment register.  It's in the program comments but I didn't test it as I'd already cut off the programming header.  Affected parts are PIC10F320/2, 12F1501, 16F1503/7/8/9, 16F1713/6/7/8/9.