DCC control of coach lighting

[Crosland]

Adding to what Suzie has said:

 

On Ac when there is a polarity reversal there is a slight time delay before the diodes become non-conducting.

This can mean the "off diode" is still conducting for a short period at the same time as the "on diode".

This produces momentary short circuit.

 

UF (ultra fast) diodes do not exhibit this problem to the same degree and are preferrable on anything oabove mains frequency.

 

Keith

 

For those who are interested, the data sheet parameter is "reverse recovery time", Tr or Trr. You want something in the 10s of nanosecond range, definitely sub-100ns.

 

Andrew

[rockmonkey]

On 09/02/2014 at 15:38, Crosland said:

 

For those who are interested, the data sheet parameter is "reverse recovery time", Tr or Trr. You want something in the 10s of nanosecond range, definitely sub-100ns.

 

Andrew

 

I am adding flicker free coach lighting on a DCC layout, following the advice on here I see we need to select/make a bridge rectifier with ultrafast polarity reversal to avoid short circuits.  I have a few DF005S rectifiers which I could install, however the data sheet parameters don't appear to include "reverse recovery time", Tr or Trr. 

DF005S - https://www.mouser.co.uk/datasheet/2/308/DF10S-D-1803768.pdf

 

I have identified an Ultrafast Bridge Rectifier which sounds ideal! again the data sheet parameters don't appear to include "reverse recovery time", Tr or Trr. 

B40 - https://www.mouser.co.uk/datasheet/2/427/800dm-1767939.pdf

Would either of the rectifiers be suitable?

 

Cheers

Phil

[Suzie]

The B40 will be fine, anything claiming to be ultrafast will be fast enough.

 

The DF005S will not be fast enough, this is designed for mains frequency operation.