Handy Continuity Tester Packs Multiple Modes Into A Tiny Package

March 25, 2018 by Dan Maloney 10 Comments

From Leatherman multitools to oscilloscopes with built-in signal generators and protocol analyzers, there seems no end to tools with multiple personalities. Everybody loves multitaskers because they make it feel like you’re getting more bang for your buck, and in most cases that’s true. But a jack of all trades is seldom master of any, and there are times when even the humble multimeter isn’t the best tool for the job.

With that in mind, [sidsingh] has developed what we think is a very nice dedicated continuity tester. With a goal of using only parts on hand, he had to think small to fit everything into the case he had. So he started with a PIC10LF322 to support all the flavors of continuity testing he wanted to support. In addition to straight continuity, the tester can handle diode testing, detecting shorted or open diodes and even differentiating between regular and Schottky diodes. It also has an LED test mode and an interesting “discontinuity” testing mode — it only sounds its buzzer when continuity is broken. The video below shows that mode in action for finding intermittent cable faults, along with all the other modes.

For an ostensibly single-purpose tool, this tester still manages to pack a lot of tests into one very compact package. Simpler continuity testers are good, too — check out this cheap dollar store build, or this slightly more complicated unit based on an ATtiny85.

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Playing A WAV File With 64 Bytes Of RAM

January 6, 2013 by Brian Benchoff 37 Comments

montage-final

[Jacques] thought his doorbell was too loud, so of course the first thing that came to mind was replacing the electronics and playing a WAV file of his choosing every time someone came knocking. What he ended up with is a very neat circuit: he used a six-pin microcontroller with 64 bytes of RAM to play an audio file. (French, Google translation)

The microcontroller in question is a PIC10F322. one of the tiniest PICs around with enough Flash for 512 instructions, 64 bytes of RAM, and a whole bunch of other features that shouldn’t fit into a package as small as a mote of dust. Without the space to store audio data on the microcontroller, [Jacques] turned to a 64 kilobyte I2C EEPROM. The PIC communicates with the EEPROM with just two pins, allowing it to read the audio data and spit it out again via PWM to an amplifier. The code required for this feat is only 253 instructions and uses just a few bytes of RAM; an impressive display of what a very small microcontroller can do.