Side Project: Stuffed Animal?

OK, so this is somewhat related to flashlights.

Last Christmas, my Mother-in-law gifted two of these stuffed animal lights to my two oldest daughters (4 and 2). This one belongs to my two year old

From the beginning, the operation of this “light” was kind of erratic. It was supposed to turn on after two short presses, off with one press, or turn off automatically after a period of time being left on. While my older daughters toy functioned properly (and still does) this one often required pressing the button a half dozen times or more to get it to light, eventually failing to function entirely. Seeing as my interest in electronics had be reignited recently, partly due to this site, I pulled it apart to see what I could do.

Well, not much interesting here (I’ll get to the purple board shortly). As far as I could tell it appeared to be getting power to the proper places and the “rubber membrane” switch (removed from board before photo) was working. I could not find any signals on the driver, so I am assuming that the controller, which is sealed over, is to blame.

Back to the purple OSHPark board. I decided if I could not get the original driver to work, why not make my own? While I have had electronics experience in the past, and even worked in a PCB assembly shop for a short time, I had never designed my own board until coming across BLF. Another BLF learned skill used is the programming used to run the new driver. I had played around with PIC controllers back in college, but working with Atmel brand is another new skill picked up here. I decided to use the Star momentary program, trimmed of unneeded things such as voltage monitoring and dual PWM, and adding a shut down timer.

I am unsure what LEDs are used, but I guess that they probably run around 20mA each. As there are 5 in parallel I setup the driver to run at 100mA. A small mosfet on the lower side of the circuit provides dimming by the PWM signal from the controller.

I ended up using a different switch, the height of which caused me to slightly modify the housing of the driver for proper function.

I found the project to be both interesting and educational. I thought that someone else may find interest in this amateurs tinkering as well :slight_smile:

Nicely done!
Runs off 3xAAA?

Wow cool mod…very neat

Need some beam shot pics, or at the very least pics of it with it’s light button lit :wink:

Very cool build…and very cool board…great job!

Lucky kids to have a smart dad.

what a great story and even better build. The stuffed animal now has a very bright future.

Now buy another one of those animals and install an XHP70 with strobe. Now you have a real “sleeper” light (get it?) and the kids can blind and disorient intruders.

my daughter’s flashlight pal just started flickering I pulled the thing apart … and have been looking for guidance! Thanks!

A "Tactical Plushie"! Toss this in through the side window when breaching the door to disorient the perps on the inside... J)

Yes, it runs off of 3x AAA

I have been thinking about a XHP70 build… :wink:

I can put up more detailed specs on the parts I used when I get a chance (when not at work). You may come up with a different solution, but mine required modification of the spacer between the driver and emitter boards, and the housing due to the slightly higher switch (2mm?) and the LED driver chip on the back of the driver.

Nice project, I am impressed how neat it ended up.
I am also interested in some details of the changes to the standard Fet circuit we mostly use., I can see a big mosfet on the bottom and a small one on top? What are they good for? Is this a constant current layout?

The component on the bottom actually is not a fet but an LED driver (self-biased transistor) from ON Semiconductor NSI45090JD As I only need the driver to supply 100mA, this chip works well, even if the package is a little large. I would have liked to find something in a smaller footprint similar to the AMC7135 and I may have found one if I had spent more time looking. R3 is used to set the output current (160mA max).

U2 is a 1.4W n-channel MOSFET AO3442 which is used to dim the output. Using this setup, the driver is current regulated, but is pulsed with the PWM signal to achieve modes below high. Currently I have 4 modes programmed (moon, low, medium, high). There is nothing here which has not been done before, and probably done better then my design. It is just easier component wise to work with the lower power in this circuit then would be used in one of the lights typically modded by people on this message board. I have toyed with the idea of designing a similar regulator with discrete components for higher currents, but I believe that heat would be a big issue.