Have a 24vac transformer that was rectified and filtered and ran the rest of the circuit. The transformer had a tvs diode across the 24volt output before the bridge rectifier and it was shorted. Repaired everything sept the tvs because I could not find the part number. This is my first encounter with a tvs. My question is how to select a new one without knowing the part number. The circuit works fine with out it, but I want to put something back. I know almost 0 on how to select one. Would this be similar to selecting a zener...?