blinking computer lights

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blinking computer lights

mlewy
Joined: 30 Jun 2015, 19:22

06 Apr 2016, 18:08 #1

Does anyone know how they made the timed blinking lights for comptuers - before comptuers.
Curious what they used to program the lights on the original star trek.
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feek61
Joined: 29 Apr 2007, 15:38

06 Apr 2016, 20:28 #2

Yes, they used motorized rotary switches.
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mlewy
Joined: 30 Jun 2015, 19:22

06 Apr 2016, 21:30 #3

Can you explain that a little more. 
 
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feek61
Joined: 29 Apr 2007, 15:38

08 Apr 2016, 17:17 #4

Sure,

A rotary switch basically has a shaft with a contact in the middle that rotates inside of a wafer (or usually multiple wafers) that have multiple contacts. When the center turns; the center contact connects with each contact on the wafer(s) as it turns thus completing the circuit and sending power to a specific pattern of lights (in the example of Star Trek bridge displays). Once the center shaft makes a complete revolution; the pattern begins again. The switches used on Star Trek were motorized and the speed could be adjusted. Typically each display had one rotary switch but sometimes multiple displays were controlled by one rotary switch (which would make the separate displays change at the same time) and in a few cases; two rotary switches control one display (which would give exponentially more patterns to the lights).

Below is an example of a motorized rotary switch which has seven wafers. You can see the individual contacts around the perimeter of each of the seven wafers. The motor is on the LH side. You cannot see the central shaft but there are 7 contacts that align with each wafer which would send power to each light or pattern of lights connected to the wafer contact that has power. I hope that makes sense!
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mlewy
Joined: 30 Jun 2015, 19:22

12 Apr 2016, 19:24 #5

yes that makes perfect sense.
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PaulMmn
Joined: 03 Dec 2016, 07:09

03 Dec 2016, 07:35 #6

This is the same technology that was found in washing machines-- the motor on the switch advanced the contacts to Fill / Agitate / Spin / Fill / Rinse / Spin / Stop.  The main difference with washing machines is that power to the switch motor ran through one of the contacts, so at the end of the cycle the last movement of the switch motor would cut off its own power!  

In model railroading one method to control lights in buildings was to do the same thing-- but use a tin can or other metal drum.  Power was applied to the drum, and metal fingers would rest on the drum and send power to various lights.  Strips of duct tape on the drum under the fingers would control the on/off of the lights.  Looked similar to the drum in a music box, with all the fingers for the notes waiting for a bump to play the correct note.

--PaulMmn
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bonesmccoy
Joined: 03 Dec 2016, 18:53

17 Dec 2016, 05:54 #7

To PaulMmn - what a great comment!
Thanks for posting that hack for model train layouts.  I've wondered how those effects were created.  Now, your comment explains it.
Duct tape and Aluminum cans... a winning combo!
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