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How do I produce this signal? [All Better!]


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The amplitude is unknown, it simply needs to click a small reed relay, I don't belive this will be a problem.

It is a continues pulse, where it goes high for .5 seconds, low for 1 second, then high again for .5 seconds, then repeats every 4seconds.

I should have said that in the first place!  :-[

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If a 5 volt amplitude is desirable, you could use a clock circuit and some logic or clock circuit with 4017s where you choose the output pins that would give you the correct timing. For a more accurate source, you could use a microcontroller. Turn the port pin on, start a 500 millisecond count, turn it off, start a 1 second count, turn it on, start a 500 millisecond count, turn it off, start a 4 second count, and loop (repeat). Such a circuit would only require a cheap micro, a clean 5 volt source, and a resonator.

MP

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"clock circuit and some logic or clock circuit with 4017s"
Could you expand a little bit on these two?
Especially the 4017s. I am familluar with those and have access to many of them.

I tried this circuit with 555 timers and got close, but it is so ridiculous! In fact, I had to take it apart and add 2 more times to it, then I probably would have needed another after that! I don't believe this circuit should require five 555 ICs!

So, yes, please, expand.

Thanks!

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Have you made one of the blinky light projects with the 4017? If so, you know that the clock frequency causes each output to fire off in a controlled sequence. Thus, if your clock signal causes each of the LEDs to blink at every 0.5 seconds, you could select the pins you want for a pulse every 0.5 seconds, 1.0 seconds, 1.5 seconds, etc. Of course, you are not lighting LEDs, but are using the outputs for pulses, instead. For example, output pins 1 and 4 would probably give you a pattern like your timing diagram and you would need a 12th sequence to re-trigger the first again at the correct timing. To get a 12th sequence, you will have to cascade 2 4017s. You basically have a 0.5 second time base and you can choose which increments you want to use until it loops back and starts over again.

MP

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