Need a circuit to generate a brief pulse each cycle of a sine wave

[jmarkwolf]

Need a clever simple little circuit to generate a brief rectangular pulse, each cycle of a sine wave. Also need to be able to sweep the point at which this pulse starts (width can be fixed), on sine waves ranging between 5Hz and 50Hz.



Can anyone direct me to such a circuit?

 

[kemiyun]

I do not know if there is literature for this kind but here's what I can think of:

Use a comparator and SR latch or D flip flop with reset. The reference voltage for the comparator will be your sweeping input. And you should reset the latch or flip flop after some inverter delays. This will generate your pulse. But the pulse width will be a big problem with this circuit if you want a longer pulse.

Actually fixed pulse width is much harder to achieve and requires dedicated Delay Locked Loops mostly.

 

[crutschow]

You can use a comparator and connect a variable DC voltage to one of the inputs to vary the trigger point on the sine wave.

Use the comparator output to trigger a one-shot such as with a 555 or a CD4098 to get a fixed pulse-width output.