Hi there, i have a humidity sensor in the cellar, its a small unit with 9v battery & a audible alarm, I wanted to hook up a 3v wyze sense sensor to it, I managed by connecting a transistor in place of the audible alarm so it sends a signal to the wyze sense.
The unit has a test button. I tested it & it works, when the sound would have been triggered , the wyze sense will indicate ‘closed’ to the Wyze app.
My question is by having the transistor btwn two systems with different voltages, 3v & 9v , am i discharging the 9v battery into the 3V one? I measured 0 Volts at the wyze sense battery terminals with the 9v battery installed in the alarm unit . apologies for the rough schematic .