Speakerguy
Active Member
I was making a simple bipolar supply +/-15V out of stuff from the scrap box. I was using a uA7915 from TI on the negative rail. Its data sheet claims 'no external components necessary". With no output cap or just a 0.1uF ceramic cap, I got a 1Vpk-pk sine wave @ 1.8MHz on top of the 15V regulated output. Sticking a 100uF electrolytic on the output fixed it. I've never seen a standard/non-LDO have stability problems without output capacitors, nor have I seen an old school regulator need them for compensation. Has anyone seen this behavior before? With the 100uF it was a nice steady regulated DC voltage.