Hi
We have to build a AC to DC PSU on friday, using the following schematics
The AC input is 15 V 50Hz, and the output must be: 9V 100mA
I need help with these problems:
1) Dimension of the Capacitor.
2) What voltage should the zenierdiode be on
3 How big should R1 be
4) Effekt lost in Q1
1) Now for the capacitor i found the 10% ripple is fine (Power Supplies)
But if i want 5% is this the right way to do it:
Vc=Vs*(1-e^(-t/RC))
15*5% = 15*(1-e^(-0.01sec/x) that gives x=0,00244 F The 0.01 sec is from the 50Hz AC to 100Hz DC.
2) Q1 needs 0.7 volts to work, so the zenier should be able to handle output + VQ1
Thats 9v + 0.7V = 9.7V
Is this right?
3) R1 = (15V - 9.7)/(Izenier + IQ1) Or is it 15V - (9.7 + 0.7V)/(Izenier + IQ1) 0.7V for the zenier?
4) Im lost on this one :S
Thx for your time
We have to build a AC to DC PSU on friday, using the following schematics
The AC input is 15 V 50Hz, and the output must be: 9V 100mA
I need help with these problems:
1) Dimension of the Capacitor.
2) What voltage should the zenierdiode be on
3 How big should R1 be
4) Effekt lost in Q1
1) Now for the capacitor i found the 10% ripple is fine (Power Supplies)
But if i want 5% is this the right way to do it:
Vc=Vs*(1-e^(-t/RC))
15*5% = 15*(1-e^(-0.01sec/x) that gives x=0,00244 F The 0.01 sec is from the 50Hz AC to 100Hz DC.
2) Q1 needs 0.7 volts to work, so the zenier should be able to handle output + VQ1
Thats 9v + 0.7V = 9.7V
Is this right?
3) R1 = (15V - 9.7)/(Izenier + IQ1) Or is it 15V - (9.7 + 0.7V)/(Izenier + IQ1) 0.7V for the zenier?
4) Im lost on this one :S
Thx for your time