>As part of my circuit, I used a relay to convert a full wave rectified
>AC input to a half wave to detect when the "time set" switch is pressed.
>This is just a series diode being switched in and out of a leg of the AC
>path to the full wave rectifier.
>
>Is there a way to do this without a relay?

Use a pair of optoisolators with the diodes wired in inverse parallel. If
both are on, then no button is pressed. If only one is on then a button is
pressed.

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