I have a time clock (prox reader) that has no contact or voltage output - other than a speaker chime. I need to actuate a turnstile on valid time clock swipe (RFID card). I'd hoped I could steal the speaker signal to actuate relay...but no luck so far.
Voltage before chime is roughly 200 mV; during chime: ~300 mV.
Is there a way to use/recognize/convert that signal to close a dry contact or generate adequate voltage to trigger relay?