Is it bad design?

[walid1]

What is the function R3
If you know that the output voltage at both ends of the 220u capacitor is 9 volts DC, is not this resistance wastes 9mAh all of time
What is the point of that?
thanks

 

[audioguru2]

If the transformer is low quality (cheap) then its output voltage is very high when there is no load. I have a cheap AC-DC wall wart with a rated output of 9V/100mA and its output is correct. But without a load its output is 19VDC.

The 1k resistor R3 provides a load when there is no other load to keep the output voltage from being too high.

 

[walid1]

thank you guru,
yes the transformer is cheap

 

[alok81]

i agreed with audio guru

 

[Will D1]

Hi,
I agree with audioguru. 1k resistor R3 provides a load when there is no other load to control  output voltage .

 

[bassamfreiha]

If the transformer is low quality (cheap) then its output voltage is very high when there is no load.Ac Dc is not supported in this transformer.So you can many option to new transformer high voltage load.

 

[remonx6]

yes i agree with walid . yes the transformer is cheap

Thanks Sir