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Create a circuit that makes 2 beeps of one tone, and 2 beeps of another tone?

What is the simplest, most cost effective way to to make a circuit so it would go Hibeep Hibeep Lobeep Lobeep, and it cant use any programable chips, no pic, all that stuff.  

AndyGadget3 years ago
Why no programmable chips? This sort of job is exactly what microcontrollers are absolutely ideal for and you could do this with an 8 pin chip, a piezo, a couple of passive components and less than a dozen lines of code.
Otherwise you are looking at a clock generator, a sequencer and an oscillator which would be at least 3 larger chips.
jeff-o3 years ago
Does it matter how much time is between the beeps? That will actually impact the design of the circuit.

(And also, it's a shame you can't use a microcontroller. That would only require a single 8-pin chip, a transistor, speaker, and a few resistors.)
mdgnys (author)  jeff-o3 years ago
Yeah it does matter, I thought somehow it would be a simple circuit. Guess I thought wrong. And now that there is no way to do it without a chip, I guess Ill have to use it.
jeff-o mdgnys3 years ago
Well you still can do it without a microcontroller. It's just that it''ll take at least three chips, maybe four, to do the job of one 8-pin microcontroller.
Re-design3 years ago
Hook a variable speed motor to a shaft. On the shaft install 2 disks. On each disk mount a two magnets that will trip a pair of "magnetically sensitive 'REED" switches". The switches when closed will turn on either of two tone generators which generate the low tone or the high tone. You will install the magnets in the correct position to make the timing right.
You need some logic gates, and some timing delays, like HC221.
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