5 V, 0,5 A Power supply design

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McPlay

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Hi

Could you please help me in designing 5 V, 0.5 A power supply without using any ICs. I can get the voltage correct but the current is too small.

Thank-you
McPlay
 

How about some specs? Input voltage? Regulated/unregulated?
 

Simply you use 7805 regulator simple to design because it has only 3 terminal.google it to find datasheet.
 

mailus said:
Simply you use 7805 regulator simple to design because it has only 3 terminal.google it to find datasheet.
Click to expand...

He said no ICs!!!
 

    V

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Specs: input voltage is 230V AC with 50Hz and ripple and noise should be less than 20mVp-p and it must be able to tolerate mains fluctuations of +/-5% from the norminal 230V
 

Well, one simple approach:
1) Step down transformer (say, 9V) followed by
2) FW rectifier bridge and filter cap. Say this gives nominal 9V output unregulated output
3) This voltage goes to the collector of an NPN transistor.
4) The base of the transistor is biased with a 5.6V zener, so that the output on the emitter is about 5V.

Also, look at this: http://paginas.fisica.uson.mx/horac...mentacion I/Documentos/Reg de Voltaje SGS.pdf
 
Hey Mcplay,

Heres something else you can do after rectifying the mains and it works with a wide range of input voltages! I tested this and it works rather well with accuracy of upto 10-25mV. Although the driving stage is not very stable, still pretty good. Just another idea/



Hope it helps
K
 
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But he says without IC. :wink:
 

I asked my supervisor to use IC component he said I can use it , please anyone who have an idea of how can I build a power supply with an output of 230v AC and produce the output of 5V dc using IC.
 

Wiseman said:
I asked my supervisor to use IC component he said I can use it , please anyone who have an idea of how can I build a power supply with an output of 230v AC and produce the output of 5V dc using IC.
Click to expand...

Did you mean input 230V AC, Output 5V DC.
 
yes I'm sorry for that thanks.
 

You give us small informations.

1. Do you mean transformerless or with transformer design ?

2. To clear situation, on end you can use IC ?



For design including transformer you can use standard circuit for 7805 :

**broken link removed**


For transformeless design you can use :

 
Last edited:
I'm using a transformer which has an input of 230V AC from the mains and output of 24V AC thank
 

How to calculate the values of these capacitors in order to achieve 5V DC as an output?
 

Which capacitors ? Capacitor dont regulate voltage to 5V, that is job of voltage regulator.

Use transformer, graetz, diode to prevent reversal polarity, 78S05 voltage regulator with small heatsink, one capacitor before 330uF-470uF, two capacitors after 100uF and 100nF, put small fuse and thats it.

78S05 will give 0,5A on output for sure, even we considering that input voltage is high >10V difference Vi-Vo.

See example:

**broken link removed**


If you want you can also use switching voltage regulators such as :



:wink:
 
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Hey tpetar,

I was looking at the transformerless design and I was not able to figure out why the pass transistor is on the return path here? Whats the idea. I figured that the zener drops 39 volts across itself and another 0,7V lost across the 10k resistor and the rest (191,3 V) is lost across the 39k and 33R resistors. but I cant figure it out. Could you please explain the working ?

Cheers
Karthick
 

FET T2 is used as a switch, which is turned off when the voltage is greater than 40 V. The gate of T2 is driven via R3 and R4. As soon as the voltage exceeds the value of 40 V, transistor T1 will conduct which causes the gate-drain voltage of T2 to be so small that T2 stops conducting. Because of this, electrolytic capacitor C1 cannot charge any further and the maximum voltage across C1 is therefore limited to about 40 V.
This voltage is converted by IC1 and surrounding components to a 5-V power supply voltage. The maximum output current is 1A.
 
The tranformer design that you gave was helpful thanks but how to calculate the values of the capacitors that you used.
 

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