To build a transformer

[sourabh]

Hi,

I need to build a 110VAC to 21VDC, 900ma transformer.

(This is to power an ACT Labs gaming steering wheel for which I lost the power brick)

Would someone be able to provide me a schematic of the circuit I need to build?

I am new to the transformer world, how would I control the output voltage 21VDC while also limiting the current 900ma?

Thanks!

[Hero999]

Strictly speaking a transformer is AC not DC, you need a transformer followed by a rectifier and capacitor to get a DC voltage.

Just because the power brick or steering wheel might be specified at 900mA, it doesn't mean the current needs to be limited to that, it's just the maximum current. To protect against short circuits a fuse can be used but it needs to be a higher rating than 900mA in order to prevent accidental blowing, anywhere between 1A and 2A will do.

Do you know how regulated the voltage needs to be?

A regulator IC such as the LM317 will provide excellent voltage regulation.

Use the following circuit but change the some of the component values:
C1 = 1500