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Hoople said:
Glider, I know it sounds confusing but it is really a neat trick to lower the supply voltage going to a device. The banded side of the diode is the cathode. As long as the anode is more positive than the cathode, the diode will be forward bias and will conduct. Because the diode has 1 silicone NP junction, a voltage drop of appox .6 volts will exist from that junction. Now if you like, you can just daisy chain junction after junction after junction and collect each .6 volt drop together as 1 big voltage drop.

Those Radio Shack diodes are 6 amps so you really can put a nice load on them with no worry at all. This trick works only in DC circuits. It's a quick, cheap & effective way to cut down a little or a lot of voltage going to a device.

I ran across the tip years ago while reading a book on "Electronic shortcuts and tips". It has helped me out of a jam a bunch of times.
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Thanks Hoop, I didn't know there was that much of a voltage drop in those diodes.
 
The good news is the diodes dropped the voltage and worked great. The bad news is they get very hot(to hot to touch in about 10 sec.). I used 6 of them so at least i know I want to drop the voltage about 3 volts.
 
That is strange. You did get the 6 amp diodes correct? Something is not right. That 1 bulb can't be drawing that much current.

Tell me what bulb you are using and I will put 1 together on the work bench.
 
Just 1 bulb?

That's a halogen bulb isn't it? I can't understand why that bulb is drawing that much current.

Was that a bulb that was designed for a headlight, hi-intensity lamp or some special application other than just a tail light bulb.?
 
they are Beacon 2 marker lights.




halogen. i used the existing wires that went to my factory led tailight. just one bulb




j@p says MR-16 halogen bulb 12v 35-watt
 
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jettblack said:
they are Beacon 2 marker lights.
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I don't know what beacon 2 marker lights are.

There is no bulb number on the base of the lamp.? If there is I can look up the specs on the bulb. There has got to be some identification numbers in order to re-order a new bulb.
 
In order for those 6 amp diodes to get that hot that fast, the bulb must be drawing a bunch of current. I would have to actually measure the bulbs current in order to answer the question why.

There is a J&P right down the street from me. I want to see those bulbs and maybe I can come up with a solution.

I mean that is a lot of load for just 1 bulb (~5 amps) to put on a 38 amp charging system.
 
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