power supply

I have build a 1.8-32Vdc/ 3A power supply, but when i turn on the power, the 47uF(tantalum) capacitor BURN! So can anyone tell me what's wrong with my schematic diagram?????

I have attach a schematic diagram in JPG format.
 

Attachments

  • power supply.jpg
    power supply.jpg
    67.8 KB · Views: 620
I recommend you do remove the 47uF tantalum. It is overshadowed by the 6800uF electrolytic, and does not really add to hi-freq noise cancellation. Replace it with one or two 100nF ceramics.

Some tantalum types (like solid tantalum) are not very good with high ripple currents. I have seen some self-healing tantalums explode violently in some (test) conditions. They seem to be limited in esr dissipation.

Bouke
 
- yes i use 50V 47uF tamtalum capacitor. At first, i have a 3A fuse attach in the circuit before the voltage pass through the 47uF capacitor, when i turn on the power, the fuse blow! And then i bypass the fuse, turn on the power again, and this time the 47uF capacitor blow!

- Is there anything to do with the diode(1N5402) and the 6800uF 50V capacitor?? Maybe i should change the diode bridge rectifier and change the capacitor to >20,000uF???

- See, i attach the schematic into multisim, and it seems like not really stabil when i view the osciloscope.

- Any other suggestion for the schematic???more reliable......??
 
jamesbooi said:
- yes i use 50V 47uF tamtalum capacitor. At first, i have a 3A fuse attach in the circuit before the voltage pass through the 47uF capacitor, when i turn on the power, the fuse blow! And then i bypass the fuse, turn on the power again, and this time the 47uF capacitor blow!


Tantal caps have bad habit to go dead-short and if availlable current is big enough they explode. They dont like heat, overvoltage(spikes?!) and especially not reverse-polarity. Ripple-current handling capacity varies wildly depending on manufacturer and series. Try something like 470uF 50v al-electrolytic + 100nF ceramics.