13V D36 and resistor ??

I recently blew a 13V D36 and removed the lamp from the reflector with plans to use the reflector for something else.....I was suprised to find a large resistor soldered inside the bezel and was potted all together in a nice little package inside the bottom of the reflector. Is this normal to use a resistor with an incandescent lamp?

Just curious as I have taken apart a few of my 9V D36 lamps and found no resistor inside. I do not remember the color of the bands on the resistor so I do not know what value it was.

Ok I have dug this resistor out of the trash in an attempt to figure out just what the value is however I can not figure it out from these colored bands. The resistor is a light blue color with 2 red bands on one end....one gray band in the middle...and one gold band on the other end. Can anyone figure out about how much voltage this lamp would be getting on 3 R123 cells?

Robocop said:

Ok I have dug this resistor out of the trash in an attempt to figure out just what the value is however I can not figure it out from these colored bands. The resistor is a light blue color with 2 red bands on one end....one gray band in the middle...and one gold band on the other end. Can anyone figure out about how much voltage this lamp would be getting on 3 R123 cells?

Click to expand...

I did a google search on "resistor color code". The two red bands should be 22 and I'm going to guess that the gray band in the middle is actually silver which would mean to move the decimal point two places to the left and make the resistor 0.22 Ohms. The gold band should be the tolerance (gold = 5%).

It sounds like Wolf Eyes' method of creating a 13V light assembley was to simply put a small resistor in series with the bulb that is normally in the 12V light assembly. Interesting.

I would suggest saving that resistor or offering it to a beginning modder, since it can be hard to find resistors with a high wattage rating for mods.

I have a couple of dead WE 13V D36 light assemblies (I had bad luck with the first two I got). I'm going to have to take one apart to see the resistor.

Well I do have a 12 volt D36 also that is very bright and I am now curious if the 12 V D36 also uses a resistor. I am actually amazed that the 13 V D36 is as bright as it is while now knowing it was resistored.

According to the Popular Bulbs Current draw thread, the WE 13V D36 draws 1.52A (compared to the WE 12V D36 which draws 1.28A).

The voltage drop across a 0.22 Ohm resistor at 1.52 Amps should be 0.33 Volts (V=IR = 1.52*0.22 = 0.3344). That doesn't seem like a lot, but perhaps it is just enough to protect a 12V bulb from the 13V input.

The power dissipated in a 0.22 Ohm resistor at 1.52 Amps should be 0.5 Watts (P=I*I*R = 1.52*1.52*0.22 = 0.508288). I would guess that the resistor itself is probably rated for at least 1 Watt, since it would be rare to run a resistor at its maximum rated power, although perhaps in an application like this that is not designed to last very long it might be done.

The total power being expended at 13V and 1.52 Amps should be about 20 Watts (P=V*I = 13*1.52 = 19.76), but that doesn't account for any voltage drop in the cells when they are under load. So about 0.5 Watts out of 20 Watts (or 2.5%) of the power is being dissipated in the resistor.


(Of course this all assumes I've interpreted the resistor code correctly and haven't messed up any of the formulas)

Robocop said:

I recently blew a 13V D36 and removed the lamp from the reflector with plans to use the reflector for something else.....I was suprised to find a large resistor soldered inside the bezel and was potted all together in a nice little package inside the bottom of the reflector.

Click to expand...

I am now looking at a dead 13V D36 assembly. How do I go about taking it apart?

I used a pipe cutter and slowly tightened the circular blade down on the bottom of the lamp assembly. If done slow you can slip the circular blade between the copper looking ring on the bottom of the lamp right at the base of the reflector. Slowly work around the base and it will force the bottom ring away from the base of the emitter. You will see a little white epoxy that is semi soft however once you get the bottom part started it comes out easily.

I guess you could use a knife blade however would probably end up cutting yourself as I did when I tried it that way...hehe

Could the 13V lamp be frosted? According to my 12V and 13V D36 beam shots, its beam is more even and difffuse.

I didn't realize that the 13V draws more current. It sounds as though it would benefit more from larger cells (168A).

Robocop said:

I used a pipe cutter and slowly tightened the circular blade down on the bottom of the lamp assembly. If done slow you can slip the circular blade between the copper looking ring on the bottom of the lamp right at the base of the reflector. Slowly work around the base and it will force the bottom ring away from the base of the emitter. You will see a little white epoxy that is semi soft however once you get the bottom part started it comes out easily.

I guess you could use a knife blade however would probably end up cutting yourself as I did when I tried it that way...hehe

Click to expand...

I don't have a pipe cutter. I gave it a quick try with hand tools but it wasn't easy to get anything between the reflector and the copper-looking ring on the bottom of it and I decided to give up before I cut myself. I guess I will have to try find a pipe cutter sometime.

On my d36-13v battery voltage is dropping to about 10.7v with 1.48amps of current through the lamp assembly. That's gonna be about 15.8 watts total with the same .5w dropped across the resistor.

The 13v bulb looks clear as glass to me no frosting there. Larger cells.....say what ever happened to/with that longer extender?

My lamp was also very clear with no frosting....On a side not I just received a few extra 13V D36 lamps from Mike and must say he is a very classy guy to deal with. Very good products and customer service make it a pleasure to buy from him with confidence.

The new 13V versions I have received seem to be a little different. On my others bought a few months back the bulb seemed to always be a little off center. These newest ones are all very well centered and seem to all have identical output between them. It may be my imagination however I could swear that these newest ones are even a little brighter and a little more white.....if that is even possible as the Wolf-Eyes are known for having good white tint for an incandescent.

Re: Wolf Eyes 13V D36 and resistor

Robocop said:

I used a pipe cutter and slowly tightened the circular blade down on the bottom of the lamp assembly. If done slow you can slip the circular blade between the copper looking ring on the bottom of the lamp right at the base of the reflector. Slowly work around the base and it will force the bottom ring away from the base of the emitter. You will see a little white epoxy that is semi soft however once you get the bottom part started it comes out easily.

Click to expand...

I finally got a pipe cutter and used it on my two dead Wolf-Eyes 13V bulb assemblies to separate the reflector from the base. It was very easy to do with the pipe cutter. The bulb and resistor are mounted in some white flexible caulk-like epoxy that I had to pick at with a pliers and tweezer to remove. The resistor measured 0.2 ohms.

Check this out:

http://www.ami.ac.uk/courses/topics/0139_gtrp/index.html said:

A resistor with a white body generally indicates a non-flammable resistor, and a blue body a fusible resistor. When a fusible resistor overheats, it cuts the current in the same way as a fuse, and both types are designed not to catch fire when they overheat. Never replace either type with a normal resistor, because this would create a fire hazard should a circuit fault occur. Otherwise the colour of the resistor body has no universal meaning, although some manufacturers use the body colour to differentiate between components with different temperature coefficients.

Click to expand...

If it's really a fusible resistor, that's damn clever.