My XHP-70 "Sleeper Light" Mod

lol - I wondered about the switch :)

Up until now, I have only been bench testing this light. Running it while not assembled and not using the stock switch. The original LED in series with the 15 ohms of resistors probably only drew in the neighborhood of 200 mA. That stock switch probably couldn’t handle 6A, even once. So I built an “FET switch” based on this circuit

This circuit with a low power LED could be used to test various FET’s in a Go-No Go situation. I eliminated the 1K resistor because in this circuit it is a current limiting resistor to power what would have been an indicator LED to signal on and off during the test of the LED. The 2 resistors I had and for the FET I used an automotive FET salvaged from a drill pack. In this case it came from a Ridgid pack, part IRF1404z. It can handle 75A so 6A is a piece of cake! Even with no heat sinking. The stock switch is a push on, push off. Push once and release and the switch stays on. Press again and switches off. Perfect for this application. Now instead of having to pass 6A, it only see a few milliamps.
Nothing fancy, I soldered the 3 components directly to the traces on the back side of the reflector.

At the top of the picture there are 2 connectors that make contact with the switch mounted in the forward top of the light. They connect when the reflector is screwed into the light.

All there is to do now is wait for darkness

Sweet. I need to keep that FET switch circuit in mind.

I updated the OP with beam shots and a short video

  1. what tint is the XHP70? it looks pretty good compared to the SRK.
  1. maybe someone can explain how that cool switch mod works. (I know dchomak posted the diagram and discussed it) but you see that assumes I / we are smart enough to follow along. Maybe if I say please? :slight_smile:
  1. What would happen with if 5s1p tired lap top pulls were used? I was thinking of the 2 volt drop and was wondering if it might work?

Thanks Ronin42, so far, you are the only one to respond after I posted beam shots, :smiley:

To answer your questions, firstly think of the FET as a valve. In fact the names of the pins are “Drain”, “Source” and “Gate”. A water valve, a “Gate” valve, would have a place for the water to enter (the source) a place for the water to exit (the Drain) and a shut off (the Gate). Open the Gate and the water flows, close the Gate and the water stops. Simple as that.
In the circuit for the FET the Gate is closed when it is low (negative) and open when it is high (positive).
In this schematic, when the switch is open, the gate is low meaning that it is negative. It is connected to negative through the 68K resistor. Close the switch and it becomes high and opens up. Even though the 68K resistor still connects it to negative, the much lower 100 ohm resistor opens it up.

Picture of a Gate Valve

Notice in the diagram they use the terms Gate Up (high) when it is open and Gate Down (low) when it is closed.

As to the tint of the XHP-70, it is definitely warmer than the SRK. When I ordered, it was supposed to be 5000K and I think that is about right. The SRK looks COLD in comparison.

And to answer your third question, I am sure the LED would blow up with 5S. I purposely used weak cells just to be safe. Better cells would not drop a lot less than as much as 2 volts.

BTW, the Sleep Light puts out a lot of freaking light. Compare it to the cars passing by. (no one would have had their high beams on though)

That's a heck of a lot of light coming out of a plastic light. Must feel a little funny holding a plastic light pumping out that many lumens. How does it feel in comparison to the SRK weight wise?

I really like that, thanks for sharing.

LOL, it vibrates!
That poor 12V fan is spinning like crazy running on 16V

It’s a flooder though for sure. Like you pointed out in another thread the reflector is shaped so that most of the lumens just spill out.

I wouldn't think the fan needs to spin very fast to effectively cool that heat sink. You planning on putting a resistor in series with the fan or something when you go to the next level of cells?

Looking forward to hearing how your XHP70 handles 4 health cells.

HAHAHA, that is some awesome sleeper man, excellent work!!!

GB anyone? :wink:

Grtz
Nico

That’s pretty sweet! Thought about resistor modding the fan to get the voltage lower?

Yes I will do, AHEM, “the resistor mod”

I’m gonna have to open her up too as pommie pointed out. It’s gotta breathe, it gets hot in there!
Heck even a “Sleeper Car” might have a hood scoop, right?
I’ll do it discreetly. 0:)

dchomak thank you so much…

Excellent, Excellent, Excellent

Wow your explanation is one anyone can follow (if I can). I had to look at it for a while but now I get how you are using the FET (look at me throwing big words around) :slight_smile: to be the actual switch. I guess with all the resistors it is not open and closed but more and less closed.

Sorry lazy brain, yes I did not take the time to check the voltages at 4s you are already over the 12v for the emitter. Better to go with 4s2p heck, you have the room.

You definitely got it, but I want to make a slight correction to your thought and 1 more analogy here.

In the picture of the water Gate valve, imagine instead of the gate being connected to a screw that is turned to open and close it, but rather just a simple shaft that can slide up and down. In the position that the diagram is in, imagine that when the gate is down it is because gravity, which is always present, pulling it down. To open the valve you have to “pull up” on the shaft, overcoming gravity. As long as you keep pulling up on the shaft, the gate is open. But as soon as you let go, it falls back down and shuts off. I like to think of that 68K resistor as though it were the gravity that keeps the valve shut off.

I did the resistor mod and slowed the fan done some.
I also did some calculations on what it would take to keep the inside of the light cool. At first I thought I could use these 2 small 25mm fans I had but based on their 2.3 CFM airflow, they are not enough to get the job done.

Those fans in a push-pull configuration in order to carry 60W of heat out of the light would have to exhaust air at 152 degrees Fahrenheit. That’s way too high. Turns out using 1- 50mm fan is enough.

Another strange thing about this light, IT GLOWS :smiley:

So much for plastic reflectors, the XHP-70 is so bright it just blasts thru the reflector!

great pictures :smiley:

Damn, that's crazy with the light going through the reflector like that. Looks like a mini nuclear reactor or something.

Looks ready for some night time drag racing and dominate the streets at night! Cool Work amigo

You sound like an old gearhead.

Back in the late 60’s, I had a sleeper car. I had built a Chevy 327 with all the good stuff and before I put it in ’63 Nova that I had waiting for it, I dropped it in a ’62 4 Door Nova. It was a junker and was painted flat black with the stock 13” tires. The front shocks were toast and it was like having NO shocks. The first night I was out with it, I hadn’t even put the hood back on. I was up on the highway, doing about 60, when a couple of guys pulled up along side EDIT: (In a Corvette) and started playing around. I floored it, my front end shot up so high I couldn’t see the road at first, and pulled them bad. They followed me off the exit ramp into a fast food parking lot, and we all just laughed our heads off.