Question regarding LM2575-12V Voltage Regulator
Posted: Wed Aug 04, 2010 9:10 am
I recently purchased some LM2575 (5 volt) regulators from lightobject.
I noticed something I didn't understand. I am using a 15 volt fixed DC supply for the input, and driving several flashing LED circuits (astable multivibrators) for crossing signals on a model railroad. (very low power demand, maybe a switching supply was a bad choice?)
When I measure the input supply voltage, I normally see 15V. When I hook up the LM2575 circuit, I see 5V on the Vout side of the device, but if I check voltage across the input supply posts, my voltmeter now reads 21V. I simply do not understand what is going on here.
Can someone explain ? Is my meter lying to me ?
I noticed something I didn't understand. I am using a 15 volt fixed DC supply for the input, and driving several flashing LED circuits (astable multivibrators) for crossing signals on a model railroad. (very low power demand, maybe a switching supply was a bad choice?)
When I measure the input supply voltage, I normally see 15V. When I hook up the LM2575 circuit, I see 5V on the Vout side of the device, but if I check voltage across the input supply posts, my voltmeter now reads 21V. I simply do not understand what is going on here.
Can someone explain ? Is my meter lying to me ?