Anyone here have experience hunting and FINDing these? I'm thinking of making the trip up to the U.P. (upper peninsula of Michigan, residents called Yoopers) to do some rock hunting. I love that area anyway so finding Yooperlites is just one more excuse to make the trip.

I've got a supply of "UV" LEDs looking for a project. I'm wondering if I were to build a panel of them, would it be useful for searching or displaying Yooperlites? I have a small UV flashlight that I'm sure would work, but surely more is better. More power!!

Background: https://mymichiganbeach.com/yooperlite/

 

Good use for the old UVEPROM eraser. You just need a long extension cord.

 

Or, a battery & inverter combo.

 

https://www.amazon.com/Indmird-Waterproof-Lighting-Halloween-Fluorescent/dp/B0B4FVY9TZ/

I have one. Freakin' bright.

 

Suppose I make my Yooper-finder with 20 LEDs, maybe a 4x5 array. How should I go about powering that? I could use an 18650 cell and give each LED its own resistor but I'm hoping there's a more elegant approach. Is there a simple boost circuit I could use, like a solar light on steroids? I'd need about 60-70V to drive them all in one string

 

I'm thinking of making the trip up to the U.P. (upper peninsula of Michigan, residents called Yoopers)

Be sure to listen to the radio for the “Yoopies.”.

Some sample lyrics from my memory:

“Well, it’s 40 below and I don’t give a (word that rhymes with truck)
Got a heater in the truck,
and I’m off to the rodeo.”

“It’s the second week of deer camp,
and all the guys are here.
We play come cards and drink some beer,
and no one shoots no deer.”

 

LOL, yes, I've had Da Yoopers' Deer Camp songs on my playlist for years.

 

I've ordered up some of these:
https://www.amazon.com/gp/product/B09MYQMMM4

I should be able to use a couple to light serial strings of LEDs from a battery pack. I specifically chose a boost converter that included a micro-USB input. I already have a great battery pack (phone recharger) that will provide plenty of juice for a long run time.

 

Here's my first experiment with the voltage booster above. I hooked up a 12V LED festoon bulb (resembles an automotive door light bulb) to the output and used my bench top PS to provide the input.


At 13.00V, this festoon draws 110mA (determined with multimeter). That's 1,430mW. My PS reads current in amps to two digits, so it's not terribly precise at this low current but anyway I recorded the current drawn by the chip versus the supplied voltage.

I'm amazed that the chip held a very constant output voltage at 13V while the input voltage was varied from 3 to 12V. It fell off below 9V when supplied just 2.00V. Another surprise, the efficiency was greater than 90% in the 3-12 range, and >97% for 4-12V.

I was adding a second festoon in series to test higher voltages when I somehow released the magic smoke. So that data will come later. Good thing I got 15 of them!

 

Fresh data. No smoke this time.

 

So it looks like I can use LED strings of 8 in series, and then several strings in parallel. I think I'll use two 18650s in series for the power supply. Supplying 8V will allow a boost to ~30V at ~90% efficiency, enough for the 8 LEDs.

Is there a rule of thumb for sizing the current balancing resistors? I'm thinking they should drop maybe 1V at 20mA, meaning 47Ω. Plus or minus to tweak the current between strings. Any better ideas?

 

I would design for a 10% drop in voltage, but that is pretty conservative.