Wiring For Bridge Rectifiers and Capacitors

[RkyGriz]

Ok. I bought the capacitors and bridge rectifiers that you guys recommended  to fix the LED light polarity and flickering problems in my J.S. passenger cars. The rectifiers have 4 mounting poles (2 plus and 2 negative each which I'm assuming that I can connect 2 LED strips each to) and the capacitors are the standard 2 pole type. Now, I need to know the proper sequence for wiring these parts into the wiring for LED's (they're strip LED's if that makes a difference)as I've never done this type of electrical work before and my current wiring setup in the cars is just direct to track power with the Bachmann on-off switch incorporated into the wiring. I appreciate any wiring advice you guys can offer. Many thanks in advance everybody!

[Joe Satnik]

RG,

A Rectifier Bridge should have 4 terminals, two "~", one "+" and one "-".

If it does not, put up a picture of what you have, and let us know its manufacturer and part number. 

Thanks.

Joe Satnik

[jviss]

Joe is right, the rectifier should be marked with two terminals for AC input, and then a plus and minus DC output.  Here's one I bought for this purpose:



The inner two terminals are the AC inputs; no polarity, naturally. 

The wiring is as follows:



The textual way of describing a circuit is to name the nodes and the terminal of the components and associate them.  If we name nodes left to right, top to bottom you have node1 being the connection between D2 and D4, which includes the bottom of the capacitor and the bottom of the load, and can be considered the DC ground, or "0V" node.  Let's call positive of an electrolytic cap terminal 1, and the anode of a diode node 1, and for the ambiguous components the topmost terminal(or otherwise leftmost terminal) in the schematic as node 1.  This yields:

node1: D4.1 D2.2 C1.2 Load.2
node2: AC.1 D4.2 D1.1
node3: AC.2 D2.2 D3.1
node4: D1.2 D3.2 C1.1 Load.1

After all that, you might want to consider a resistor between the rectifier and the cap, since a discharged cap looks like a dead short circuit for a short time, until it accumulates some charge  The bigger the cap, the longer this condition persists.  This could exceed the rectifier's current handling capacity, and burn it out.  I kinda doubt that, though, as there is probably enough bulk resistance in the rectifier diodes to limit the inrush current sufficiently.  (That said, there might be sufficient bulk capacitance in the LED's to make the discrete cap unnecessary).

The circuit for this would be:

node1: D4.1 D2.2 C1.2 Load.2
node2: AC.1 D4.2 D1.1
node3: AC.2 D2.2 D3.1
node4: D1.2 D3.2 R1.1
node5: R1.2 C1.1 Load.1

I'm curious, what components and values were recommended?

Thanks,

jv