This is an hypothetical question, not for the real build.

Let say there are 64 filament bulbs runs on AC 240V mounted in 8x8 matrix pattern. These lamps are to be controlled by only 16 switches (8 switches mounted in x direction and another 8 in y direction), where the coordinate intersections of these switches (total 64 points) represent the 64 lamps.

In this configurations, any two switches (one in x and another in y) will turn on only one lamp.

What is the best way of accomplishing this built with minimum components and minimum wires.?

  • \$\begingroup\$ Accomplish what? What this setup is expected to do? \$\endgroup\$
    – Eugene Sh.
    Jan 22 '18 at 20:05
  • 2
    \$\begingroup\$ It sounds like you have answered your own question. \$\endgroup\$
    – HandyHowie
    Jan 22 '18 at 20:06
  • 1
    \$\begingroup\$ 8 row switches connect to 240V, 8 column switches connect to AC return. Lamps only illuminate if their row/column switches are both active. \$\endgroup\$
    – vofa
    Jan 22 '18 at 20:07
  • \$\begingroup\$ @vofa it cannot be that simple. How if we want to lit up two different coordinates? \$\endgroup\$ Jan 22 '18 at 20:21
  • \$\begingroup\$ 'if you want to lit up two different coordinates?' Then I suggest you edit that new requirement into your question. At the moment, it reads like you only want one lamp at a time, exactly the question vofa answered! \$\endgroup\$
    – Neil_UK
    Jan 22 '18 at 20:24

It's not really clear what you are trying to do. Apparently switching 8 rows and 8 columns isn't good enough for some reason.

If the problem is bleed-thru, then you could put a small solid state relay (SSR) at each junction. Get ones with a single LED on the input. Now you use low voltage to drive the SSRs, and they in turn switch their lamps to the bussed high voltage AC power.

Due to the LEDs in the SSR inputs being diodes, this won't cause any bleed-thru or partial conduction for some of the nearby bulbs from the one that is addressed.

You also don't need relays anymore to drive the rows and columns. That can now be done with digital logic.

If you get the type of SSR that switches off at zero crossings, you can use this as a memory effect to light combinations bulbs at a time. Using the high speed digital logic, you scan all the bulbs you want to be on quickly shortly after the power line zero crossing. They will then stay on until the next zero crossing. If you can scan in a short time relative to the power line period, then you can have arbitrary patterns of bulbs on at a time.


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