BPM Generator with display

displaygeneratorintegrated-circuittimer

Trying to figure out how to design this with decent precision but having trouble getting this started. I've worked with 555's before but not for precise counting that can be modified in steps.

I'm trying to come up with a 5 volt system that accurately pulses an output of +5v that is measured and displayed in pulses per minute, or beats per minute, between 60 and 240. The BPM should be adjustable by 2 momentary buttons which will step the timer +1 and -1. It would also be great if there could also be a second set of buttons for +10 and -10 steps.

Is using a 555 timer the wrong way about this? Is there something more precise I can use to reference the gating? Is there already an IC out there that can do this on its own and do a compare to calculate the maths?

Apologies for not posting what I have so far. I'm on version 80-something on my breadboard and nothing has been working accurately so far. I also want to stay away from having to program roms and stick with discrete IC's. Again, I DO NOT want to be programming chips.

I think what I'm after might be a function generator with a frequency counter, but I don't know if that's the best way to go.

Best Answer

If you want to implement something without using any programmable parts beyond a custom-frequency oscillator, it should be possible to build a circuit that takes a 3-digit BCD frequency and outputs a signal with that many beats per minute using an oscillator plus five off-the-shelf chips. Feed a 1,092,267Hz oscillator into a CD4060 to scale it down by a factor of 16 (DIP-packaged oscillators at Digi-Key have a 1Mhz minimum speed). Feed that 68,266.7Hz signal into a cascaded sequence of three CD4527 chips set up for the "ADD" mode to yield an output of (1-999)/4,096bpm, and feed the output of that into a CD4040 to get the desired output rate as well as various power-of-two multiples and submultiples of that. Higher taps of the first CD4060 may be used to provide various power-of-two multiples of 66.7Hz [perhaps usable as "beep" tones].

If you have three BCD thumbwheels, you could would only need six main electronic parts, all DIP; quantity-one prices at Digikey would be:

3x CD4527BE  -- $0.80ea ($2.40 total)
2x CD4060BE  -- $0.56ea ($1.12 total)
oscillator   -- $3.02ea ($3.02 total)
                         $6.54 total

Assembly should be fairly straightforward on 0.1" perfboard since the only interconnections other than power and ground would be the oscillator output feeding the first CD4060, the output of that feeding all three CD4527, each of the first two CD4527 feeding two signals to the next, and the last CD4527 feeding one signal to the last CD4060.

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