The doctor is in

The USB Charger Doctor, that is.IMG_20141028_152728I went on a small eBay shopping spree, though it was mostly restocking some components like resistors, capacitors, and some RGB LEDs. The only interesting item in the mix was this USB Charger Doctor which reads out the voltage and current through a USB connection. I bought it because I’ve always been curious to see exactly how much current my devices were drawing. I tested the stock charger for my Nexus 7 (2012), the stock charger for my Samsung Galaxy S2 Skyrocket, and that battery pack I got from China. The results are all over the place, and I like that.
IMG_20141028_152420The voltage regulation of the two chargers and battery are not bad. It seems as though all three test subjects can sway +/-200mV with or without a load.

A bonus test was with my Powerocks 2600mAh battery. It’s of much better quality than the China battery pack in build quality, and as gives a very nice regulated 5V compared to the 5.08V (no load) output of the China battery pack.
IMG_20141028_152600 The current tests were what I was really interested in. I got some pretty fascinating notes out of it.

The picture above is my Skyrocket (phone) being charged. When I was doing this test, it would actually pull that 910mA only when the screen was on. It would drop down to around 400mA when I turned the screen off. I suspect it’s a current limit for the battery when it’s already charged to >90% which is what it was during that test. As I test it now with my phone around 70%, it draws a consistent 960mA regardless of whether the screen is on or not. The Samsung charger for my phone is rated at 1A so the charger is perfect.

As for the Nexus 7 charge test, it was pulling 910mA. I find that curious since the included charger is rated for 2A. Perhaps it’s a software limitation, or a change in the Nexus 7 hardware after the charger was already designed?

The current test for my China battery pack was the one I was most interested in because I wanted to know how much current it draws so I could use an appropriate charger to charge it. There’s no label for the input current, unlike the Powerocks battery, but it’s not like I’d put much trust in it if it was labeled anyway. Using the Doctor, I see it pulls a constant 700mA so any one of my 1A chargers would suffice.IMG_20141028_185028It was pretty neat to see what was going in with the batteries and chargers I’ve been using for years. I’ll still have to play around with it more as my tests have been pretty quick and not very practical. I would totally recommend one of these USB Charger Doctors if you’re interested in seeing what your devices are drawing. Thanks for reading!

Code dump of Light Show files

I wanted to let everyone know that I’ve dumped all of my Light Show code files (.ino) into a directory over at the Arduino Light Show website. I’ve lost some files over time so all of the files you see in that directory are all the files that I have. Hopefully this ends the requests (and straight up demands) for code.

Update (10/17): I decided to do a little more work on the Light Show website. The Code Directory is an actual page now and you can now watch each video directly on the website.

The towers have returned

In version 3 of the Arduino Light Show Project, I constructed a backdrop with some cardboard and tissue paper. I made towers out of the cardboard but kept one side open and used tissue paper to diffuse light from an RGB LED inside of each tower. I hadn’t started using version numbers for the light show then so my working title for that version was “Towers Light Show” which was reflected in the names for related files (pictures and code). The towers backdrop idea will return for the next light show but in a much more simple form.

In my previous post regarding the new light show, I talked about how the planning for the backdrop was going and ended that post with a bit of a teaser. I guess it’s a bit misleading since I don’t think I’m going to end up using that prop in the show or even in an experiment right now. The idea was a plain flat backdrop with protruding shapes with LED backlights so that the shapes would have kind of a glow. I decided not to bother with the idea right now since I came up with something a little easier for me to construct.

rgbtowersThis is the result of my light test. The tower is about 17cm or 6.7″ tall. I do expect them to be taller in the final build. Moving the LED a distance from the tower allows it the light to cover all of the tower face which was an issue with the first backdrop test. I couldn’t do the same thing with that backdrop because the light from the LEDs would be interfering/mixing with each other. With 7 separate towers, I can space them out so that there wouldn’t be much light mixing together on the towers, or at least that’s the theory.

I’m set on this plan because I have the materials for it (at least, after I order some more RGB LEDs). I have a few other tricks up my sleeve but they shouldn’t be too complicated (they’re things taken from previous version of the light show). Pretty much the last thing I need to figure out is if and where I should use my shift register boards. I think the Mega should have enough pins, but I haven’t checked. I’ll get on that so I can draw out a master plan on paper.

I hope to get started on the build very soon. BTW, this will be Light Show 7! Stay tuned for updates!

Attiny85 Programmer/Breakout Rev B3 Preview

Let’s go back to basics, shall we?preview1_frontI decided to throw out the whole breakaway section idea. It complicated things and there’s always the chance of a bad break. I put everything back on one board, which is now down to a 3x3cm footprint, 38% smaller than Rev A. The space savings come from less silkscreen text (removed the word “Pin” for the pin numbers) and using SMD components for the power LED indicator and resistor. I would have gone with an SMD capacitor but it costs more than the usual through-hole electrolytic capacitor, at least from where I get my components for these boards. With the price appearing to go up to get these boards manufactured, I’m looking for savings.

preview1_backAnother thing that changed with this sub-revision is that all of the pads are circles and are bigger than they have been on previous boards. They were kind of a pain to solder because any circular pads were really thin. I’m still working out the right size but I’m happy that I know  out how to address that issue now.

To date, the Attiny85 board was my most “Watched” item on eBay so I take that as an indicator of interest for this kind of thing so I’m set on getting these made. Being 3x3cm, I can’t fit two on one 5x5cm board which is what I have to work with to get manufactured. I’ll probably do something simple with the rest of the space but I want to nail down this one first. Thanks for reading!

Backdrop Test, Take 1

I’ve been planning out the stage for the fountain show. I hope to have something ready by December so I can do both a music compilation show as well as a holiday special for the end of the year. Some minor alterations will happen between those two shows. Since I tend to lose interest after the first show, I want to put together a really good stage since I only expect to get one or two shows out of it.

I did some testing on one idea I had for the backdrop of the show. You should expect to see something like the first fountain show but with a backdrop and additional effects.IMG_20141007_113542When I did a quick project using my AMS1117 board, one of the wires broke so I decided to fix it up. I used the voltage regulator board for this experiment. I had to remove the headers soldered on and replace them with wires going directly to the battery holder. I put some shrink tube on the exposed connections since they’d be touching without it. It’s nice to see that it still works even though I had my soldering iron on the board for a long while trying to get the headers off.

IMG_20141007_140609Anyways, this is a prototype section of an idea I had for the backdrop. It’s kind of like an “accordion” shape made out of cardboard that has one white side that’s perfect to light up with LEDs. The main purposes of this test was to see how the backdrop would look, and to decide if I should use clear lens or diffused RGB LEDs.

The issue I have with this backdrop is that it seems like I’d be forced to pair LEDs with another on the top since the light from the LEDs don’t go that far up the backdrop. The thing is, I was planning to make the backdrop even taller since it would be a bit short to go with the fountains. There may end up being a dark zone in the middle of the backdrop if it’s too tall.

IMG_20141007_140446Now regarding the RGB LED type, I’m set on using diffused LEDs for the backdrop which is pictured in this image. The clear lens type works well with the fountains since the water acts as the diffuser, and these LEDs also serve well as spotlights (even though the light from each color don’t point at the same place). Since they make for great spotlights, they tend to make shapes in the light which is not ideal for the backdrop. I could put something over them to diffuse the light but I might as well just use the diffused LEDs. I’ll have to order more, though I need to finalize the backdrop. I have a couple more ideas for a backdrop so I hope to have some more prototypes to share soon to help me make up my mind.

Stay tuned…


Chinese Power Adapter Teardown

IMG_0198I got this power bank yesterday from China. Obviously it’s not a Samsung product but the power bank does seem to work fine. I wanted to make sure that it wasn’t connecting to data so I sliced the cable open. It only connects the power wires, thankfully. I bought a cheap USB voltage and current measurement tool on eBay but it won’t be here for a long while, especially with their national holiday. I’d like to measure the current coming out of the outputs.IMG_0187Anyways, it came with this really sketchy power adapter. The USB slot is like a half USB slot where your plug doesn’t fit in all the way or latch in properly. You can also feel the assembly was loose inside of it by just shaking it. I was definitely not planning on using the plug so I decided to open it up and see what was inside.IMG_0188Three sides of the front plate were already loose. I just had to slide a knife down the fourth side and a quick tug on the plug popped the assembly out.IMG_0189There’s a transistor between the transformer and a capacitor but there’s barely enough space for it so they put it on an angle. For whatever reason, the other transistor nearby is also at an angle and they’re both pushing over another capacitor. I thought it looked funny.
IMG_0190Dave from the EEVBlog explains in a video what’s crap about it, more than I ever could, but it was interesting to look at one myself.
IMG_0199Here’s a closer look at one of the boards.

So yeah… I’m not expert enough to rip on the board, but anyone can point out it’s a piece of junk just by holding the thing.