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# Where do the leads of a zener diode connect to in a DC system? Answered

I have a light in my car that takes two incandescent type light bulbs, but when I use both sockets, the bulbs are broken open and some of the glass is melted in a couple weeks. I've bought plug and play LED lights that have multiple LEDs (with a resistor on both the cathode and anode) and just plug into the sockets, and I used both sockets, they lasted about two months. And since I had only one spare bulb in my center console, I plugged it in, and its been working for over a year (this is where I found out that using both sockets made the lights fail). I'm guessing that the when the engine starts, it sends a surge to the light.

So I decided, that I'll just make my own light using LEDs, I have everything resistors LEDs and wire, but I'm unsure where to connect a zener diode/s to the LED array (or if a zener diode would even protect the array). I've looked on the net, but some say to solder inline and some say it needs to connect to the ground, and I cant tell which is right for my case.

I've included the output of the LED calculator and the specs. below.

Source:                     12V
Diode Forward:       1.8
Diode Amps.:          20mA
Number in Series: 24

Solution 0: 6 x 4 array uses 24 LEDs exactly
+----|>|----|>|----|>|----|>|----|>|----|>|---///----+ R = 68 ohms
+----|>|----|>|----|>|----|>|----|>|----|>|---///----+ R = 68 ohms
+----|>|----|>|----|>|----|>|----|>|----|>|---///----+ R = 68 ohms
+----|>|----|>|----|>|----|>|----|>|----|>|---///----+ R = 68 ohms

The wizard says: In solution 0:
*each 68 ohm resistor dissipates 27.2 mW
*the wizard thinks ¼W resistors are fine for your application
*together, all resistors dissipate 108.8 mW together,
*the diodes dissipate 864 mW total power dissipated by the array is 972.8 mW
*the array draws current of 80 mA from the source.

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