Electronic – What are the ratings of vintage Selenium Rectifier B20/16-2,4


Sort-of a follow-up to How to ground a vintage device that was powered without a ground? in that the device is the same.

I finally took the leap and opened up the old charger (depicted in the linked question). The plan is to replace the Selenium rectifier/s by Silicon. The Se rectifiers have two marks as follows

Selenium Rectifier in battery charger

  • Vertical '15360'
  • Horizontal 'B20/16-2,4'

Here is what I hope to find out

  • What is/are the ratings of this/these Selenium Rectifiers?
  • Should I use 1N4xxx, or 1N58xx in lieu of the Selenium?

Best Answer

You're unlikely to find specs on the selenium rectifier. However, you can probably get a pretty good idea from context. You must know something about the device this is in.

Chances are, a 1N4004 can be used as a replacement, although you might have to put a resistor in series. The old selenium rectifiers had significant resistance, and sometimes the circuit relied on that, like to limit inrush.

These rectifiers were usually limited to the power supply, so taking a measurement of the power supply voltage or otherwise inferring it would be useful.