USB 4GB rechargable key torch

Hi folks
This project started a while ago after looking at some threads of key-chain lights which inspired me greatly, i wanted one badly, so why not make it then?, i am not done yet with this one, it is still undergoing some run-time tests and needs some more head-scratching for assembly

I had seen somewhere a photo of a bunch of keys, included was keys/mini torch/mini knife and a USB stick, much head-scratching later we get this

a basis rundown of parts
1- body, from a nearby pound shop, for a pound
2- a 4GB USB memory stick, an old one which is a spare
3- led driver old stock in my parts packet PETZL 4 mode with boost
4- lipo battery from long dead mini helicopter
5- charge circuit to charge lipo cell when USB connected
6- XPG R5 LED with an aspheric lense

All these parts were had already, except for the charger, this has taken a fair amount of time including setbacks

Not tested yet is the charger coupled to memory stick in operation as im not yet brave enough to de-solder the micro usb tabs, however the charger is operational and perfect so-far charging to 4.1V then cutoff

This a the first time etching for me, this is the charge circuit using a MAX1811 chip
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Close up
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Red light is on indicating charge, thats a 3mm LED for scale
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now here is the host, from a pound shop
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here dismantled, i had to destroy the clicky in the rear completely for removal
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and finally here are most of the bits to go inside, hopefully...................................
the XRE was for testing and will be swapped with an XPG, i shall have to machine a housing for the XPG and aspheric, then
figure out where to put the momentary switch.........:huh:

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Nice work, the 1811 is a good chip for a usb charger, hope it all comes together good.

Man, this is way more elaborate than mine. Whether or not I was one of many to inspire you, I'm looking forward to see the new heights of USB key-fob glory.

I use direct-drive NiMH because that can trickle-charge and the voltages are such that it can't damage the cell by discharging. I haven't yet built one like that with a power LED, but my prelim tests make it look darn bright.

had a minor setback, the driver is refusing to turn on, i may direct drive via a resistor to the XPG, i also need the status LED's visible whilst plugged in, one for charging and one for the memory stick.

recycler said:

had a minor setback, the driver is refusing to turn on, i may direct drive via a resistor to the XPG, i also need the status LED's visible whilst plugged in, one for charging and one for the memory stick.

Click to expand...

A shim of clear plastic can work as a lightpipe to get light from status LEDs out from under opaque components. I drill a small cone into 1mm thick plastic, set this cone over the SMD status LED on the drive, and epoxy it in place with clear 5-minute epoxy. Mind how it drips.

i haven't thought of that, its a neat idea, it wouldn't be a problem moving the charge led, but the surface mount status led is very small indeed, i may be slow with the updates, back to work i go.............