#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE HOW TO#
#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE UPGRADE#
#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE FULL#
#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE SERIES#

#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE UPGRADE#

You can measure the voltage drop of the diode under a slight load (like a headlight) and just find out,The simplest upgrade would be to simple get a 25amp rectifier bridge, bolt it to a suitable sized heatsink and you're done.If the secondary has 3 wires (center tapped) then you only need 2 diodes instead of 4 (of double the peak inverse voltage though), or you just use 2 of the diodes in the bridge module.Even radioshack has these.Last edited by MikeGyver at 05:03 AM. A 10 volt drop would make it absolutely useless due to the massive amount of power the thing would waste.

#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE FULL#

Full wave flips that negative portion to the positive side and uses it (as pulsating DC).And the voltage drop a selenium rectifier is around a volt.

Half way just blocks the negative side of the sine wave, wasting it. Most battery chargers are only half wave rectifiers that charge the battery during the peaks of the AC cycleNo they're full wave rectified. I have built power supplies but only by copying from books like the arrl ham radio bible. They are still manufactured for exact replacement purposes but are not designed into new equipment.Because in theory a sel charger should be 24 volts if it does drop 10 in the rectifier.

#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE HOW TO#

Perhaps find a Honda dealer that would have a new part for it, or try to find someone who can figure out how to rewire it for a silicon diode. Youll need to replace it with one that will handle enough current though.

During the 1960s they began to be superseded by silicon rectifiers which exhibited lower forward voltage drop, lower cost, and higher reliability. Selenium rectifiers often fail after 20 or so years of service and you can replace them with silicon diode rectifiers. By far the most common failure mode was a progressive increase in forward resistance, increasing forward voltage drop and reducing the rectifier's efficiency. During catastrophic failure they produced significant quantities of malodorous and highly toxic fumes that let the repair technician know what the problem was. One point is: 'Selenium rectifiers had a shorter lifespan than desired. The shortest answer is: Generally each cell has a reverse voltage rating of around 20-25V. This thing can not be used with any modern car as it will blow the electronics to pieces. The selenium stack's about done for, and when abused for too long in 'cranking' mode, one of the diodes will sometimes 'pop' with a foul stench following the report.

#REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE SERIES#

An inductancre in series limits the current to give a 10A charge to a 12v battery, and to go to 'cranking' mode an oil capacitor is put across the inductor to resonate and it pushes 150A or better. I still have a battery charger I made from an old Sorensen 28V 50A Nobatron. Co-workers often think I resort to divination or dark arts. It sounds like a lot of fuss but it's very logical. adjust until you get proper current/voltageĢ.) disconnect the transformer from the input of the selenium rectifier,ģ.) and short the output of the selenium rectifier,Ĥ.) then feed DC through both input legs (if it has two), limiting the current to the rated current,ĥ.) and hastily read voltage drop across the stack.Ħ.) turn off the other supply and put things back the right way. if so replace with adequate silicon diodes and a variable low value resistor. The forward voltage drop & reverse leakage current increases to some degree as selenium ages, perhaps up to 7-10 percent if I recall correctly, but it probably varies. Of course military nomenclature may vary from that used in commercial gear. If memory serves I think there is an AMfone thread on this subject or similar from the past year or two and some charts posted so you might search the database here. Rectifier manufacturer catalogs from that era might also include specs and I have found several on the web. I don't have either at hand at the moment to check.

The E&E handbook might include a chart as well. Tom - If you have an ARRL handbook from the 1950s, it should include a chart with the specs for several selenium rectifier types, which might help. Unless you can find a data sheet it is a shot in the dark. I have an old military power supply that has a selenium bridge rectifier for a 12 volt supply, what would the typical voltage drop across one of those old devices be? Thanks!!

Replacing a selenium rectifier with a silicon diode