Total Charge 3, On then immediately off

[yurtle]

What would be the point in using a bridge rectifier (four diodes) instead of two diodes? A bridge is normally used on non-center tapped transformers, while using a center tap transformer only needs two diodes.

[JohnnieB]

Originally Posted by yurtle

What would be the point in using a bridge rectifier (four diodes) instead of two diodes? A bridge is normally used on non-center tapped transformers, while using a center tap transformer only needs two diodes.

It depends on what is lurking in your parts stash.

For the legacy chargers with two diodes on a heatsink, I'd stick with discrete diodes. They are only a few dollars each. However for something like needing to replace the $50 diode assembly in PW-II, I'd think about Jerry-rigging a $5 bridge.

[yurtle]

Seems like you could use half of the transformer with a bridge, or the transformer with half of the bridge?

By "bridge", I'm referring to either 4 diodes or a single component that is essentially 4 diodes in a single package. Is that what we're talking about?

[JohnnieB]

Originally Posted by yurtle

Seems like you could use half of the transformer with a bridge, or the transformer with half of the bridge?

By "bridge", I'm referring to either 4 diodes or a single component that is essentially 4 diodes in a single package. Is that what we're talking about?

Yep, that's what we're calling a bridge.

The fact it is a ferroresonant transformer complicates things. I'm not sure what the resultant charge profile would be if only half the transformer was used.

If the capacitance of the boost capacitor drifts, the output amps change, so that probably limits what can be done in the secondary(s). I suspect there is some degree of latitude, but have no idea what it is.

[yurtle]

Ah. Didn't concider what happened downstream. Then he'd use half of the bridge.

[rockfordpi]

Originally Posted by JohnnieB

It depends on what is lurking in your parts stash.

For the legacy chargers with two diodes on a heatsink, I'd stick with discrete diodes. They are only a few dollars each. However for something like needing to replace the $50 diode assembly in PW-II, I'd think about Jerry-rigging a $5 bridge.

Yes, I have several 50 amp Bridge Rectifiers I need to use and since I had done this in the past I wanted to do it again just for the challenge and to see if I still could AND save $5 in the process, LOL.

Obviously, if I factor my time into the equation, I would come out way ahead buying the stud diodes, but also would not have near as much fun and satisfaction.

The fun is not having it working, the fun is making it work. Back in the day, I spent about 60 hours building a PC/atmel based linux smart card emulator (Pitou) so I could watch ANYTHING on Direct TV for free while avoiding ECM's. It worked and I got all of the PPV and movie channels and still kept watching TV land Reruns.

After I paid for the parts and $300 to DTV to settle the civil suit, I would have been much better off with cable, LOL, but again would not have been nearly as much fun. BTW, the SOL has long since run and DTV encryption is bulletproof now, so I can talk about it.

Anyway, I will do a bit more refresher research and let you know how it turns out.

[yurtle]

Use a DMM and determine each "diode's" anode and cathode on your bridge. Draw a typical 4 diode bridge and label it according to your bridge's terminals. Then simply compare your diagram with a scematic from any charger. Should be straight forward. Test with a smaller source if you have any doubt. You can always test with DC as well.

I built this around 2001 or 2002, got 4 boxes and lotsa cards, a dual LNB dish and a switch from garage sales, and had all channels and infinite PPV on 3 TVs and a computer with an ATI All in Wonder card. Then my 11 year old found the smut channels, so I programmed them out.