Messing around with LED camping lantern

[FrankenMech]

There are tweaks and they obviously do them do decrease that time in the transition zone. That optomization is why established designs are usually better than roll your own solutions.

[humanshield]

I'll take your word on that. I haven't experimented with or read up on JT circuits

[Deleted]

This video demonstrates an example of why you want high frequency and high voltage in some applications. This Joule Thief circuit is driving a gutted CFL and, we get a lot of light and no heat at all...none. We can do the same with some led applications. In this circuit, the switching is done by the TIP3055 transistor, which works really well and was selected by the designer of this circuit, Jeanna, after a lot of trial and error. I added a variable resistor to the circuit so I could more easily tune to hit resonance and, maintain it as the input voltage from the battery drops. I replicated this circuit because I was amazed at seeing a CFL being powered by a "dead" AA battery. I can use C or D sized batteries in this also.

Bill

I forgot to add that this circuit puts out well over 1,000 volts.  At this frequency, it is hard to get an exact measurement with my scope.  Others that have built the same circuit say 1,200 volts and still some others claim closer to 2,000.  No matter what it is exactly, it is still high voltage and folks building this need to be careful. (The actual output drops as the input battery voltage drops so, there is always a voltage output range.)

[FrankenMech]

You have way too much fun, -Naw, we all need MORE fun!

I love your battery contacts.

[humanshield]

Well, I dint' use a JT circuit this time but I did find a great use for a large 5,200 mAh LiPo battery I had bought for an aircraft that ended up not working in that aircraft.....


It's a 4S (4 cell) LiPo battery so 16.4v is about where it sits fully charged so I was thinking what could I use that for.

It so happens I have a LED camping lantern that goes up to 750 lumens so I found a great way to use that battery with my lantern and now I have a rechargeable battery pack for it that can run my camping lantern for up to 24 hours on a single charge and still be well above the 3.4v lower threshold.



I added a Coaxial DC Power port to the lantern obtained from Radio Shack item number 274-1563 and soldered it to the existing positive and negative soldered connections for the original battery pack inside the lantern.
It looks like it came with that DC power port from the factory doesn't it? 



I used a LM2596 DC to DC converter to go from 16v provided by the battery down to 6.2v for the lantern. The output voltage is adjustable to ANY voltage less than the input voltage. Awesome! These are available on ebay for under $3.00



Then I added one of those RC battery voltage monitors (also available on ebay for a couple bucks) so that I could have it alert me when the battery voltage was down to 3.4v per cell. The voltage monitor and DC power converter are velcro attached to the battery for neatness.



The white container box for the LM2596 is also available on ebay for about $9.00

Now I can use ANY of my LiPo batteries for my lantern. I thought this DC to DC converter was awesome. The possibilities are endless.
I can use ANY of my LiPo batteries for practically anything where rechargeable battery power is practical

[FrankenMech]

Fantastic job!!!

[humanshield]

Thanks Frank!

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