diode bridge using trannies

sss · 18th October 2003, 06:54 PM

hello everybody

i'm working on a SMPS and i need a fast diodes to make a bridge
i wonder if i can use transistors as fast diodes , for example taking emmiter and base and connecting as one diode
the switching freq is not too high - 10khz.
i got many mj15003/4 trannis can i use those as diodes?

Christer · 18th October 2003, 07:01 PM

Why would you want to do it??

I don't have the datasheets for those particulat transistors
at hand, but most transistors won't perform very well as
rectifying diodes. The max reverse voltage of the BE diode is
usally on the order of 5 - 10 V only and the current handling is
not likey to be very good either. The BC diode would stand
more reverse voltage, but I guess there are still problems with
the max base current, not to mention the base resistance.

sss · 18th October 2003, 07:08 PM

oops , i forgot th reverse voltage

i got no fast diodes but i got many trannies
thats why i wanted to use them instead

18th October 2003, 06:54 PM	#1
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	diode bridge using trannies hello everybody i'm working on a SMPS and i need a fast diodes to make a bridge i wonder if i can use transistors as fast diodes , for example taking emmiter and base and connecting as one diode the switching freq is not too high - 10khz. i got many mj15003/4 trannis can i use those as diodes?

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18th October 2003, 07:01 PM	#2
Christer diyAudio Member Join Date: Sep 2002 Location: Sweden	Why would you want to do it?? I don't have the datasheets for those particulat transistors at hand, but most transistors won't perform very well as rectifying diodes. The max reverse voltage of the BE diode is usally on the order of 5 - 10 V only and the current handling is not likey to be very good either. The BC diode would stand more reverse voltage, but I guess there are still problems with the max base current, not to mention the base resistance.

18th October 2003, 07:08 PM	#3
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	oops , i forgot th reverse voltage i got no fast diodes but i got many trannies thats why i wanted to use them instead

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