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Old 10-10-2017, 09:59 PM   #28
Don't ask, I don't know!
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Join Date: Jun 2017
Location: Chalfont St Peter
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This has been a pretty entertaining evening (for me)

Although there are many ideas floating around now, I will still add what I've discovered.
Purely because it's all new to me, and it was quite enlightening.

The hex Schmitt trigger, CD40106 BE from Texas Instruments.
Most of my experiments centre around this IC.

You can get a simple delayed on.......logic state I from this chip.
6 times=6different delays, each out can run at least 3 LEDs (maybe more, unchecked)
Very simple circuit, one electrolytic cap and one resistor per channel.
(That would cost about 3 for all components except veroboard)

The only issue is once the delayed on sequence completes, that's it, you're stuck in logic state I until you power down.

What happened next!
(After a bit of fiddling I discovered you must break the + feed to the 40106 to reset, breaking the - results in all LEDs returning in on state after closing switch)


Yesterday's circuit was still on the breadboard, I took a feed from the output of the 555 chip (pin 3).
Used this to provide the+Vcc for the 40106.
What happens now, you get the same slow rate switching as per yesterday's experiment (using 220uF cap, otherwise all else is the same as cad mans original circuit)

When the LEDs switch state on the 555circuit it resets the Schmitt trigger.
(One led on only, then one led on which feeds cycle on Schmitt trigger, repeat)

I have only rigged up 3 channels on the 40106, my next thought is use a 556IC
(Basically a pair of 555 timers in a single package)

Half the Schmitt trigger is fed by half of the 556, repeat on opposite side.......
Edit (This can not work) Vcc can't be split
But you could feed a second 40106
Work in progress!

Still follows a pattern but 6 channels with at least 3'leds each+ the pair per half of a 556 = at least 22 LEDs that switch on/off.

I'm using (set at) 9v power supply (switch mode wall wart) 1A max.
Could use a battery?
Might run at less V.

To change the RC time constant? On 40106
You can use either one capacitor and a selection of resistors
Or a selection of capacitors and one resistor
Or a combination of both........
This makes it versatile but not truly random.

Link to vid will follow shortly.......

You can only drink so much lemonade

Last edited by AviatorAtHeart; 10-10-2017 at 11:48 PM.
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