I made a dual +/- 12 V power supply for synthesizer circuits using a schematic by Moritz Klein (image below). The input of the supply is from a 12 VAC transformer.
After soldering the circuit on a prototype board (pad-per-hole) and testing it with my oscilloscope and multimeter, everything seemed to be working fine. I got a little too confident and tried to find out just how much it could do, and connected a 12 VDC motor between positive and ground, then negative and ground. Then I figured that if I connect +12 V and -12 V across a 24 V motor, it would power it just fine.
The LM7912 negative voltage regulator then stopped working, outputting -14.5 V and producing a lot of heat. It is also possible that I shorted the output of the power supply. I would like to know how I killed it, so that I can avoid repeating the mistake after replacing the voltage regulator.
My question is specifically: was it the high demand of the motor that killed the regulator, or connecting +12 V and -12 V? I have seen op-amps powered by the +12 V and -12 V of this specific power supply, would that be different from connecting a normal resistive load to the supply?