| ??? 08/30/08 13:52 Modified: 08/30/08 13:54 Read: times |
#157869 - Again, what do you want to protect??? Responding to: ???'s previous message |
Is it the mains transformer, then you must take what the manufacturer demands! And you must put it close to the transformer, nowhere else!
If the mains transformer is already protected, why adding a polyfuse? To protect the rectifier? This is better done by using strong rectifier diodes, if the mains transformer isn't too stiff and limits the short circuit current by itself. To protect your circuit? What is in your circuit, that needs an extra protection additionally to your mains transformer fuse?? Take care, transformer issues can hardly be calculated in full detail, but must also be tested, best in cooperation with the transformer manufacturer. Another hint: Safety class II power supplies often suffer from surge and burst. So, put 10...47nF caps across each rectifier diode. Otherwise all the overvoltage is dropping across the small pn-junctions' capacitance of rectifier diodes and will blow them!!! Kai |
| Topic | Author | Date |
| Polyswitch... | 01/01/70 00:00 | |
| First, what do you intend to protect? | 01/01/70 00:00 | |
| preemptive... | 01/01/70 00:00 | |
| AC vs DC | 01/01/70 00:00 | |
| Polyswitches vs fuses | 01/01/70 00:00 | |
| re polyswitches a 'trick' | 01/01/70 00:00 | |
| yes, but.... | 01/01/70 00:00 | |
| the \'thing\' will recover | 01/01/70 00:00 | |
| Again, what do you want to protect??? | 01/01/70 00:00 | |
| RFID device protection | 01/01/70 00:00 | |
Your transformer is much too weak... | 01/01/70 00:00 |