3 ms·
IBM's 1402 card reader (1959) used something similar to diagnose timing issues. The "dynamic timer" consisted of a spinning neon bulb that could be connected to
by kens 6y ago
IBM's 1402 card reader (1959) used something similar to diagnose timing issues. The "dynamic timer" consisted of a spinning neon bulb that could be connected to various signals in the card reader. When the signal was activated, the bulb would illuminate, at a particular rotational angle. By checking the position of the illuminated bulb against the angle scale, timings could be checked.
For instance, it was critical that each row of punched holes in a card passed under the brushes at the right time for the computer to read the values. The dynamic timer would show 12 orange lines in a circle, indicating when each hole was being read. If these lines were in the wrong position, the brushes were adjusted until the timing was right.
You can see it in action halfway down my page about the card reader: http://www.righto.com/2018/02/repairing-card-reader-for-1960s.html http://www.righto.com/2018/02/repairing-card-reader-for-1960...
- Animats 6y agoThat rotary form of timing indicator was quite common. It showed up as an automobile spark timing indicator used in repair shops, and in fathometers for boats.
- jhallenworld 6y agoThe strobe scope version is still available: https://www.harborfreight.com/timing-light-with-advance-40963.html https://www.harborfreight.com/timing-light-with-advance-4096... And I remember seeing a few of the rotary fishfinders / depth sounders still in use in the 1980s: https://www.ebay.com/i/322412202248?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=322412202248&targetid=915850928613&device=c&mktype=pla&googleloc=9002077&poi=&campaignid=9338046851&mkgroupid=94993845019&rlsatarget=pla-915850928613&abcId=1139336&merchantid=6296724&gclid=CjwKCAjwltH3BRB6EiwAhj0IUF2l-GY9A9y79k8kF83-JvzOR-qew2I3mqtLDS-CtBlaU3eIEY26rBoC0moQAvD_BwE https://www.ebay.com/i/322412202248?chn=ps&norover=1&mkevt=1...
- spongeb00b 6y agoThe Apple Disk ][ 5.25 floppy drive has a disk inside with 2 patterns. When spinning under a florescent light the pattern appears to not be spinning when the drive is at the right speed. The 2 different patterns are there for whether you have 50 or 60 Hz mains power.