Analog Blinken Grid

64 LEDs in a matrix on a wireframe controlled by 16 astable transistor oscillators to resemble a computer panel from a 70's TV show

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Everybody likes blinking lights - especially on panels. Right? This project is meant to try to make something that will flash a bit like the panels on computers from the tv shows back in the late 60's and 70s.

Making them flash with a Microcontroller would be too easy and a bit of cheating, so I'll do it the slightly more tedious analog way - 8 oscillators that pulls the rows in the grid to ground and then another 8 oscillators that pulls the columns to power.

By the oscillators running at slightly different frequencies due to component tolerances the patterns change over time looking both random and at the same time have some continuity to them.

The oscillators are the standard 2-transistor stable's with an extra NPN or PNP as the LED driver.


1 - Size matters
2 - Soldering the grid 
3 - Frame bend-styles
4 - Oscillators
5 - Assembly
6 - Final results - with videos

  • 64 × LEDs Electronic Components / Misc. Electronic Components
  • 40 × BC547 NPN transistors
  • 8 × BC557 PNP transistors
  • 40 × 10k resistors
  • 32 × 1M resistors

View all 8 components

  • Final results

    matseng01/26/2019 at 00:13 0 comments

    The finished device looks rather good, not bad at all actually  - if I say so myself.  ^__^

    The finished Blinkenpanel
    The finished Blinkenpanel

    Below is a video of it running on a single 3 volt coin cell battery:

    Running at full 5 volts with diffusor:

  • Assembling the parts

    matseng01/25/2019 at 23:51 0 comments

    I tried my best to make soft corners on the two power buses that will form the frame around the LED grid, but it was very hard to get the sizes and spacing between the two even enough. So I ended up with just plain square corners bent with pliers .

    To keep the distance between the two frames I installed a small electrolytic capacitor in each corner.

    Then I added all the oscillators spreading them out evenly among the top/bottom respective left/right edges.

    The inner frame is the VCC so all four resistors are connected to it.  The outer ground frame is connected to the common emitters of the transistors by a jump-wire that is bent so it doesn't short out the VCC frame.

  • BJT oscillators

    matseng01/25/2019 at 23:24 0 comments

    Since the LEDs are in a matrix I need to have the oscillators both push VCC into  columns and also connect GND to the rows. So I need two different types of modules for that

    The oscillators themselves are just the bog-standard two-transistor, four resistors and two caps thingie.  And to be able to push and pull current I added a NPN driver transistor to eight of them, and a PNP driver to the remaining eight.

    Using 1uF caps and 1M for the timing resistors I ot about 0.7Hz when running at 5 volts, slightly slower at 3 volts.

    Schematics for the two types of oscillators
    Schematics for the two types of oscillators

    Eight of each of the two types of oscillators are needed for the 8x8 matrix.

    Soldering the oscillators
    Soldering the oscillators

    I re-discovered the usefulness of using blu-tack to hold parts while soldering - but even  using that it took quite a while to freeform 16 oscillators with 9 parts each.

    The oscillator with a NPN driver
    The oscillator with a NPN driver

    This is one of the NPN-driver oscillators that pulls a row to ground when active. The PNP oscillators looks more or less the same except for the top transistor that is in a slightly different position to access VCC instead of GND.

  • Frame bending

    matseng01/21/2019 at 13:29 0 comments

    The power bus/frames will be rather large with sides at 30 cm / 1 foot and I suspect that they might become a bit rickety with only made with a single 1mm wire each.

    So I tried to straighten two wires at the same time using the usual technique - and it worked just fine!

    But now I have to choose how I should do the corners - either just straight square 90-degree bend or a a smooth bend.

    The grid inside the frame is very strict and square, so it might look good to have the frame a bit soft to contrast to the inside.  Or it might look out of place... I have a hard time choosing.

    Double-straightened wire with two bend types
    Double-straightened wire with two bend types

    I think I'll go for the soft bend - and maybe I should make the radius even larger....  Hmmmm....

  • Soldering the grid

    matseng01/21/2019 at 12:20 1 comment

    Since I learned how to make straight and nice pieces of wire when I did my WireZ80 for the Circuit Sculpture Contest I quickly made sixteen pieces of 22 cm wires while my 3d-printer churned away at a small jig I made in Fusion360.

    The jig doesn't cover the full 8x8 area, but rather just a smaller 4x4, but that is enough to keep the LEDs straight and spaced perfectly.

    Since the LEDs are white high-brightness I did some tests and found out that a 2k2 resistor in combination with the voltage drop of two transistors lights them up enough to not be annoyingly blinding. 

    Soldering the LEDs onto the horizontal wires, and then the resistors followed by the vertical wires took about two hours.

    Using the jig to solder it up nice and straight
    Using the jig to solder it up nice and straight
    The finished grid
    The finished grid
    Closeup of the grid
    Closeup of the grid

  • Size matters

    matseng01/21/2019 at 12:04 0 comments

    To get a feeling of the actual size of the grid at different spacings I decided to print a few samples on paper (and taped together to full size).  I tried 30mm, 25mm and 20mm spacing.

    My original though was that 30mm maybe was a bit on the small side, bu after printing it I discovered that it rather was too big.

    I settled for 25 mm (about one inch) between the 5mm LEDs.

    Around the grid of LEDs there will be a frame made out of two steel wires for the power distribution.

    Then the oscillators will then be freeformed and put between the grid and the frame.

View all 6 project logs

Enjoy this project?



Elliot Williams wrote 02/07/2019 at 14:10 point

Beautiful!  We should have run a freeform circuit sculpture contest or something...

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davedarko wrote 02/07/2019 at 14:40 point

the one that he won? ;)

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Jarrett wrote 02/07/2019 at 19:45 point

nah, it would never work

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Mark Jeronimus wrote 02/04/2019 at 20:06 point

It's a long time since I've seen transistors being drawn that way. Where did you pick that up?

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matseng wrote 02/04/2019 at 21:11 point

Probably back in the late 70's. It was a long time since I actually saw any of these in the wild in any modern context, but there's some variants of it used in the 60's which was probably to differentiate the from contact point transistors.

Today I tend to use it when I just want to draw a quick and dirty sketch by hand since they are faster do draw compared to the "regular" symbol.  And luckily enough they are still easily recognizable by anyone used to the the regular symbols.... 

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Morning.Star wrote 01/22/2019 at 20:21 point

Nice :-) I tried that with #Daisy which I have yet to complete. Not as easy as it sounds lol, I hope you get it blinking nice and random. ;-)

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matseng wrote 01/26/2019 at 00:18 point

It is blinking away now. The component tolerances makes the patterns slowly change and morph into new patterns over time.  II'm really happy with the outcome.

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Dan Maloney wrote 01/21/2019 at 16:53 point

Loved the WireZ80, can't wait to see this one blinking!

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matseng wrote 01/26/2019 at 00:17 point

It is aliveeeee!  And is actually really good looking both unpowered and while running.

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