Let’s talk regulators

IMG_20140918_193021As you probably know by now, I have released a few of my “old” circuit boards for sale on Tindie. Actually, they’re all revisions of previous boards I’ve shown off on the blog before. The one board you have not seen revised yet is my AMS1117 3.3&5v fixed voltage regulator board, pictured on the left. I’ve been looking over the design, while also straying away from it looking at other low drop out (LDO) regulators.

Functionality of the original board was not a problem. I still use these boards for prototyping and testing, and also in my final project builds like in my 24/7 powered ESP8266 project. The worst part of the board are the capacitors because they’re so close to everything else on the board including each other. I didn’t leave enough room between the larger capacitors so they’re awkwardly pressed up against each other. It’s so bad that I used hot glue to keep them solid in place because some of the capacitors aren’t sitting flat on the board. This can be easily fixed in the next revision by moving to SMD parts, which has been the plan for all of the boards since I decided to revise them all.

IMG_0767With the drop out voltage of the diode (reverse input voltage protection) and the regulator itself, you’re required to supply at least 7v to get 5v out of it. That’s the same thing as everyone’s favorite LM7805 which has a drop out of 7v, without a protection diode which would add another ~0.7v to the total drop out of your regulator. With that said, I pretty much only use 9v batteries with my AMS1117 board because it meets that minimum input voltage without being too much over. I have the ESP8266 project powered 24/7 so I’m obviously not using batteries but a 9v wall power supply.

spx1117circuit
SPX1117 schematic in Eagle – “Improved Ripple Rejection” circuit from datasheet

Speaking of wall power supplies, it introduces another “issue” if you use one with a voltage regulator. I don’t own a bench power supply or oscilloscope so I can’t get down into the fine details of  better monitored current draw or frequency response. You don’t have problems with frequency response with batteries because they output a solid DC voltage. However, with wall power supplies, the power from the wall is a rectified sine wave which is bound to have ripples in the output. I’ve been considering the change to the SPX1117 regulator which has a circuit in the datasheet to reduce the ripple… but then I wonder how much this actually matters to anyone. For hobbyist projects which is what these boards are made for, it’s really not going to have any major affects to it, as demonstrated in my projects that have worked well with the regulator board for extended periods of time.

I’m not really sure which regulator I’m going to go with. The main reason for looking at the SPX regulator is because they’re more readily available from my go-to suppliers than the AMS regulator. I may even just put the regulator circuit on the boards that would need them, like the ATmega328p breakout board. That’s the biggest motivation for designing these regulator board anyway. In that case, I probably wouldn’t need a regulator that can put out as much current (800mA)… We’ll see! Thanks for reading!

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Presenting the ESP8266 Capsule!

This project went exceptionally well. With just under two weeks of prototyping and 3.5 straight hours of soldering, the ESP8266 Capsule is complete! The project as I’ve been showing you in previous posts has been crammed into an enclosure (a food container). Let’s take a look at how the soldering went.

IMG_0001The only plan I had was a very rough schematic of the project. I skipped the perfboard planning on paper which is something I started doing with my projects that ended up on perfboards. I thought the circuits were simple enough to wing it… While that’s was somewhat true, it was challenging at times but it all worked out.

IMG_0002I pulled apart the prototype since I had the schematic to work with. I used fresh ATmega328p and AMS1117 boards since I like to have a couple rough assembled ones laying around for prototyping with.

I used some cut jumper wires that still have the female connector on it to connect up the LCD. The ones I used were actually cut off of the old Box project that was sacrificed for this project. I like to think of this as the Box 2.0 since it’s pretty much the same thing, except it gains an internet connection but loses the real-time clock.

IMG_0003This was about halfway through the soldering process. I got increasingly concerned with all of the connections flying out everywhere. They’re that long just for assembly. They would be cut down when it was time to connect everything together.

IMG_0004The first test was scary, as it usually is. The LCD lit up but didn’t show anything. After a few minutes, I realized the potentiometer that adjusts the contrast of the text was turned all the way down for some reason. I thought it would have stayed the same since it was directly taken from the prototype.

The only real issue was with the photoresistor. One of the legs had a loose connection that I had to touch up with my soldering iron a couple more times to get right. I would have liked to hot glued parts of this project but I don’t think I have enough glue for my glue gun. I put some tape in hopes that it’ll help things stay in place. Everything is so tightly packed in there, mostly because of the female connector for the LCD connections, so things aren’t shifting around too much inside.

IMG_0006This is the final product. The sensors are mounted on the top with the LCD underneath it. Beside the LCD is a switch to turn on and off the LCD backlight.

It looks very similar to the Light Timer Project since it uses the same kind of enclosure and LCD. I’d like to think I’ve progressed since then. There are no breadboards tucked in there, and I’m using some custom PCBs… That’s progress to me!

IMG_0007I find that inexpensive switches are hard to find so my previous projects usually never had one unless I had a switch I pulled from an old toy or something. My switches from China finally came in yesterday. They’re cheap and don’t fit in a breadboard, but they work great in the project.

Now that it’s in the enclosure, it can be moved around, especially since it can still be powered by batteries. I’m thinking of leaving it outside for a day and watch the data come in. It’ll be a designated day I’d announce since I’d have to pick a good day to do it. The enclosure is hardly weatherproof, and the power in contacts are fully exposed. I could put it in a bag, but I think that would affect the humidity readings. I’ll let you know.

Thank you for following along with this project! Stay tuned for more projects coming soon!

Here are some links for this project: MYSQL Database Live DemoThing SpeakGitHub Repository

ESP8266 Project Powered Up

As I said in the previous post, I wanted to get a power supply for the ESP8266 project instead of using batteries. I decided to go to the nearby electronics store today to get one.IMG_0001This power supply is 9VDC 1A and actually comes in a branded box for the Atari “Lynx”, an old portable gaming system from the 80’s. I’m curious to know if the newer (I’m assuming) and smaller power supplies that were also in the store are any better than this one in terms of efficiency. I bought this one because of the cheaper price and it has the CSA and UL listings which is nice to have.

I also picked up a new soldering iron tip, and the 9V battery clips came in the mail today. I used all of these things to get the power supply into the project.IMG_0003I soldered the power supply wires to one of the 9v battery clips backwards so it would clip into another battery holder that would be the power input to a project. This way, the project can still go battery powered if I wanted to move it somewhere away from any power outlets temporarily. The power supply can also be shared around to other projects if it even needs to be.

With the project powered up from the wall, I have it uploading information again. You can view my Thing Speak channel here. The code is available on GitHub if you’d like to try a similar project.

I am waiting for some switches in the mail, along with other things I don’t really need anymore (parts for the temperature sensor that was supposed to be for this project). Anyways, I want to add a switch to the LCD backlight so I can essentially turn off the LCD when I don’t want it on. That would be the last connection in the prototype. From there, I’ll need to decide what will be soldered where and try to get it into an enclosure.

Thanks for reading!

Look ma, no Arduino!

IMG_0001I’m one more step closer to finishing up the hardware for this project. I’ve migrated everything over to my ATmega328p and AMS1117 boards.

I said in the previous post that I didn’t want to power this project with batteries so I should mention that the battery will be swapped out with a 9V power supply so it can stay powered 24/7. This was just to test the configuration of the boards.

Thanks for reading! I’ll get it back online soon enough!

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…

IMG_20141007_184115

AMS1117 Board Test Results

In my last post, I talked about assembling my two new PCB designs. In this post, I’ll talk about the results of some tests with the AMS1117 dual fixed voltage regulator board.

As I was assembling the board, I had realized that I hadn’t accounted for the voltage drop of the diode. It wouldn’t be an issue, except that  I wrote that the maximum drop out of the AMS1117 is 1.3v on the back of the board. Theoretically, there’s a dropout of 2v with the reverse polarity protection diode in the circuit, which is about the same dropout as the LM7805 voltage regulator. I’m glad I put in the diode though, since I’ve accidentally connected the battery backwards a few times already.

Anyways, I don’t have a variable voltage supply so I built an LM317 variable voltage regulator on a breadboard for this test. The test was to ramp up the voltage to see when the 3.3v and 5v outputs would appear so I can measure the dropout.IMG_20140919_101619

You can find my test notes here. Basically, I found that the total dropout with the diode for the 3.3v regulator to be 1.74v and 1.59v for the 5v regulator. I’d round up the total dropout for both to 1.9v, or 2v to make things easier. I chose the AMS1117 instead of the LM7805 because of the lower dropout, but I forgot about the protection diode. I’m still glad I went with it because it reduces the board size significantly, and the SMD soldering is fun.

Test results for the ATmega328p Breakout Board should be posted soon. It was a pretty basic test, which it passed. Yay.

Thanks for reading!