The TC-102 is a legacy instrument designed as a monopolar device (+V only) for regulating the temperature of resistive heating elements. This device is no longer made and is superseded by the TC-202 family of controllers.
The TC-202A is a more sophisticated instrument that can actually switch between resistive or Peltier driven applications. In resistive mode, it can regulate resister based, heat-only devices or Peltier based heating-cooling devices.
The TC-201 and TC-202 are designed to power Medical System's heating devices only.