Anyone have an idea what's inside the following switching wall wart which
was supplied for a SB5101 cable modem which takes "12VDC" and at glance
runs an internal on board switcher to 3.3 VDC.
Leader Electronics Inc.
I.T.E. Power Supply
P/N: 503913-004
model no: MT20-21120-A00F
input: 110-127V ~ 60Hz 0.25A
output: 12.0V = 750mA
outside of plug -, inside of plug +
efficiency level: IV LEI-4 Made in China JL Rev 1
The output seems ok on a DMM (11.7 VDC) but it consists of a sawtooth of
about .4 V peak-to-peak with a period of about 8 mS (powerline is 60 Hz)
and a 50 ohm load. (1 V pp with 100 ohm load!)
It's clearly a switching supply as it's very light weight... Why/How the
sawtooth at the full wave power line frequency?
was supplied for a SB5101 cable modem which takes "12VDC" and at glance
runs an internal on board switcher to 3.3 VDC.
Leader Electronics Inc.
I.T.E. Power Supply
P/N: 503913-004
model no: MT20-21120-A00F
input: 110-127V ~ 60Hz 0.25A
output: 12.0V = 750mA
outside of plug -, inside of plug +
efficiency level: IV LEI-4 Made in China JL Rev 1
The output seems ok on a DMM (11.7 VDC) but it consists of a sawtooth of
about .4 V peak-to-peak with a period of about 8 mS (powerline is 60 Hz)
and a 50 ohm load. (1 V pp with 100 ohm load!)
It's clearly a switching supply as it's very light weight... Why/How the
sawtooth at the full wave power line frequency?