Changing a 12vAC tap to a 12vDC one?

lordpankake

Member
Messages
9
Hey there,

I have a FAME DCT-200 power supply that provides two 12V outputs at 250ma, but one is AC and one is DC! I was wondering if there was any simple way to change the AC output to a DC one so I could chain them together to power my wireless unit on my board.

Thanks!
 

jjohannes

Member
Messages
103
Not really, it would involve rebuilding the entire supply, more or less. Do you need more than 250 mA DC? Otherwise just use a splitter on the DC output.
 

jnepo1

Gold Supporting Member
Messages
15,247
What effects do you need to power, there are good PSUs that start at slightly just over $100.
 

stinkfoot

Member
Messages
6,138
Yup, you could build a rectifier/regulator circuit to get DC from that output. But it won't be 12 volts DC - you'd need 15vAC or so to be able to get regulated 12vDC at the output.
 

jjohannes

Member
Messages
103
12 VAC would give almost 17 VDC when rectified (not accounting for diode voltage drop), wouldn't it? More than enough to drive a 7812 regulator to give 12 VDC. But that won't solve the problem since the OP needed a 300 mA output!
 

stinkfoot

Member
Messages
6,138
A 12vAC output would (after being rectified and filtered) produce about 15 volts (more or less, depending on the actual line voltage), which would run a 78L12. But that's without any load. There are voltage regulators that can handle up to 300mA, but how close is that load to the AC output's max load? The closer you get, the lower the voltage will be, so you'd need quite a margin to get sufficient DC voltage into the regulator.
 






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