I’m making a small batch of Redemption adapters for your Atari 5200.
The Redemption adapter allows you to play games that use “digital” controls using a more reliable controller than the stock 5200 controller: namely a Sega Genesis/MegaDrive gamepad or other Atari 2600-compatible joystick for 1-button games. (2-button games can be played with a Sega Genesis or Sega Master System controller.).
A second variant of this adapter (green label) works only with Atari 7800 compatible controllers.
Steve from Wired-Up Retro shows the 7800 version of this adapter.
I neglected to tell Steve ahead of time that this type of adapter only works with 7800 controllers. That is by design. If you want one that works the 2600 joysticks or Sega controllers, get the brown label version designed for Genesis/Atari.