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Pit123:
Assuming these wireless devices are your problem, then you could use a rechargeable battery, a lead-acid gel cell, as the power source, and float a charger across the battery. That charger might be your current power supply. Might need a current limiting resistor between the supply and the battery.
What is a power meter that reads voltage? What is its response time? Are you merely watching the meter to see the voltage drop to 112, or does it have a minimum reading capability?
Your plug-in supply simply may be a transformer, rectifier, and filter capacitor. This will have an output voltage proportional to input voltage with some small lag. Or it may be a semi-regulated switching supply; or a full regulated switching supply.
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