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jgeorge

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.
1 August at 19:27 | Open on oldbytes.space
6 comments
jgeorge

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 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.
1 August at 19:38 | Open on oldbytes.space
jgeorge

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.

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...

1 August at 19:48 | Open on oldbytes.space
jgeorge

IBM Audible Random Timer lolwtfbbq thread, part 8 of apparently 8.

Thats all for now until I can put a meter or logic probe on this thing to figure out more in detail how the counters operate or what that giant rotary switch does.

I'll answer any questions with my best guesses, or show more detail of the PCB for anyone that wants it.

I'm here all week. Tip your server. Try the Ceasar Salad!

1 August at 19:52 | Open on oldbytes.space
InkySchwartz

@jgeorge The hyperfocus counter is one possibility the other would be trigger a human started activity. What activity, no clue.

Honestly I can think of a ton of use cases outside of IBM.

2 August at 13:08 | Open on mastodon.social
Kenneth Finnegan

@InkySchwartz @jgeorge my guess would be random sampling for process control. Buzzer goes off, you grab the next device off the manufacturing line and put it in the "process control samples" bin.

A lot of statistical process control methods rely on "random" sampling, and humans are REALLY bad at random.

2 August at 13:22 | Open on social.afront.org
chris

@jgeorge There are many possible applications for a random timer, like test engineering (get another cup of coffee, umh, check equipment status), quality control (take a sample... of coffee) or security (patrol the area... of the coffeemaker).

2 August at 13:43 | Open on social.inzeiten.de
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