Where is the voltage regulator on my 1993mazda protege

was it the right new alternator
possible that it is the voltage regulator and if that is part of the ECM then a new ECM
take it to an accredited auto electrician and have the charge system fully checked out

Genearly it is in your alternator

Check the voltage of electrical system when car is running. Should always be around 14 to 14.4 volts. If voltage dips to area around 12, either the alternator is fubar or the voltage regulator is not doings its job.

Thanks for the info.

You need to find if your car has an integrated or separate voltage regulator; if separate, the regulator is probably at fault. If you don't have a service manual, I can recommend the Haynes series:
Protege manual
It is one of the best $25 you can invest and will aid you in deciding whether a job is DIY or should be done by a shop.

Either the alternator is bad or the voltage regulator is bad in the PCM. I hope it's your alternator, as the PCM is your computer, and it isn't cheap.

THE VOLTAGE REGULATOR IS INSIDE THE PCM AND NOT THE ALTERNATOR. IF YOU KEEP BURNING UP THE ALTERNATOR THEN THE REGULATOR IS OVER CHARGING. YOU WILL HAVE TO REPLACE THE PCM TO FIX THE PROBLEM. THE PCM IS LOCATED UNDER THE CENTER CONSOLE IN FRONT OF THE SHIFTER.

may have bad gas or you need a tune up
have your timing check
you may need fuel filter or injecters may be clogged

Voltage regulator is built-in to the alternator assembly.

Have you tried replacing the battery?
A battery with a shorted cell will not charge properly and may even damage an alternator or regulator.

Note1: use a digital voltmeter (about $25 at Lowe's or Radio Shack) and check voltage across batt terminals while engine running. If more than 12.6 Volts DC and more typically about 13 Volts, then the alternator is working.

Note2: from Jan 98 to May 98 shows a different part # alternator than June - Dec 98
check the manufacture date on your driver door edge.