IBM Audible Random Timer lolwtfbbq thread, part 1 of however many.

This is a legitimate IBM product. Not for sale, clearly an internal - probably Field Engineering - tool. Here's some exterior views of the device. It's a plastic hobbyist project box about 45x70x110mm in size. It was originally plain white plastic, but this one has been brush painted gold. My best guess is Testors gold model paint that used to come in the tiny glass bottles with impossible to remove caps (https://www.dickblick.com/items/testors-enamel-paint-gold-14-oz-bottle).

Tell #1 it's an actual IBM product: Anyone knowing IBM machines from this era (spoiler: mid 80s) knows that stamped serial number tag. Proper tag, proper stamping, proper typeface on the stamp.

IBM Audible Random Timer lolwtfbbq thread, part 2 of however many.

Boring pics of the inside of the plastic case, showing whoever painted it did actually (good for them) test the paint to make sure it wouldn't damage the plastic.

Juicier pics coming, I promise. :)

IBM Audible Random Timer lolwtfbbq thread, part 3 of however many.

GUTS

PCB front and back. Tell #2 it's IBM made are the yellow bodge wires on the back of the PCB to add a couple of diodes in (IBM has a specific bodge wire color scheme, yellow means it's a rework done in manufacturing). Tell #3 are the rectangular tantalum capacitors with IBM part numbers on them.

5615372 and I are old, old friends. That's a standard issue double capacitor part that's been in use since Ramses II was Pharaoh of Egypt. They'd be standard parts for an IBM PCB design.

IBM Audible Random Timer lolwtfbbq thread, part 4 of however many.

How it works - overview.

The slide switch selects off, low volume, or high volume. "Low" volume is quite low. In a quiet room it's noticeable but not jarring. High volume is quite a bit louder, bordering (to me) on annoyingly loud in a quiet room but probably acceptable with any other ambient noise.

When powered on, it beeps 4-5 times to let you know it's working. Then, randomly, it will beep again 4-5 times and stop. You can stop the beeping by pressing the slide switch (it's also a pushbutton). If you leave it alone it'll beep those same 4-5 times then stop.

So far, with only a few (6-8) datapoints, the "random interval" has been between 7 minutes and just over an hour.

Beeper is a little piezoelectric buzzer stickytaped to the inside of the front panel.

Also, IBM-made tell #4 is the front panel. It's the same thickness and material as IBM machine nameplates and is the same screen printed technique.

IBM Audible Random Timer lolwtfbbq thread, part 5 of however many.

How it works - detail.

The right side of the PCB are two 4060 binary counter ships and a 74HC688 8 bit comparator. This is I think where the "randomness" is generated - assuming the two counters run at different rates, the comparator would trigger the alarm when the two counters hit the same number at the same time.

IBM Audible Random Timer lolwtfbbq thread, part 6 of however many.

R1 nearest the buzzer wires is a volume adjustment. I just realized that, and realized it's all the way down. Turned up this thing is SCREAMINGLY LOUD EVEN ON LOW.

R11 is a pitch adjustment for the alarm, and it's EXTREMELY touchy. Only about 5% of the range of the pot runs through audible frequencies, even just putting a finger on the pot will change the pitch significantly.

No idea what the 12-position rotary switch at SW2 does yet. Changing it doesn't seem to make any obvious difference so far. My theory is that switches between various resistor combinations to affect the time scale of the "random" events, but it's hard telling with so few data points so far.

IBM Audible Random Timer lolwtfbbq thread, part 7 of however many.

Non-Audible Random Musings

All the chip dates are 48th week of 1983, meaning this device was probably manufactured early 1984 or so.

There's a belt clip, so this thing is designed to be worn or at least carried on your person. The best any of us have been able to come up with it that this was a way to keep someone from hyperfocusing on something - you get lost in your work, and are off in the weeds looking at something but maybe not realizing how much time has elapsed while you've been hyperfocusing, and this thing might have been around to remind you of the passage of time without being annoying.