Do I need a voltage regulator when converting ac voltage from an adapter to dc?

Question

I have an 1800ma ac adapter, converts 110 ac to 9 volts ac. It looks just like a typical ac to dc adapter, just that it’s output is still ac. The output voltage reads as a constant 9.6 volts. What I’m needing is a dc output

I have bridge rectifiers and capacitors to convert to dc, but no 9v regulators. Do I really need to use a regulator for the output since the ac output is already regulated?

Philomel · Answer

Actually it depends on the current requirements of the load and the current capability of the converter (wall cube).
You could use a single diode and RC filter called a half wave rectifier circuit. 
How muck current does the load need?
How much current does the 9VAC adapter put out?

qrk · Answer

The output of the transformer isn't regulated. You have losses in the transformer which will cause a change in output voltage if the load changes.

Rectifying the 9.6V with a full-wave bridge will give you about
12.2VDC = (9.6 * 1.414) - (2 * 0.7)

You will need a series regulator to give you stable 9VDC. You can buy a 3-terminal device or make one from a pass transistor, some resistors, and a zener diode.

John · Answer

The grid is already regulated, why regulate it twice? I would build my own power supply. Power supply means DC and only a few parts, and relatively inexpensive.

oldprof · Answer

Understand 9V AC is about 5.6V DC equivalent.  So if you need 9V DC you're not going to get it from what you have.

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Do I need a voltage regulator when converting ac voltage from an adapter to dc?

4 Answers