Mega + 8 RFID readers...best approach?

We're trying to get 8 RFID readers connected to a single Mega. The issue we've run into is after 2 readers are connected the voltage drops.

What's the preferred method for connecting a large number of RFID readers to a Mega?

thanks

You need a regulated 3V3 power supply capable of supplying the required current. You need a separate chip enable pin for each reader either from 8 output pins or a multiplexer.

Thanks for the info.