(Part 2) Best products from r/diyelectronics

Arduino - Looks good.

Light strips - That's a rigid PCB, I think; I'm guessing you want something flexible. Here's the most popular type of strip, though Adafruit has other strands of different lengths, LED densities, and LED types: example A
Some rigid alternatives:
Example 1
Example 2
Example 3

Toggle button: Bear in mind that's an on/off button - it will be "on" after a push, then "off" after another. If you want to use it as a power switch, it's perfect. But if you want to use it as a "change color" switch, it is non-ideal (though still usable). For that application, a "momentary switch" is better.
Here's an example

Dial - This is a rotary encoder, which outputs a certain "byte" of information indicating which position its in (see this). This will work for your application, as long as your friend knows or can figure out how to code a rotary encoder. Not hard to do, but can be tricky to wrap one's head around initially. If you want to use it to change LED colors, that would work fine. If you want to use it to change LED brightness, you'd be better going with an "analog" dial like a potentiometer. Here's how you would set it up. The idea is that you'd adjust the potentiometer to read a changing input voltage, and the Arduino will adjust its output to change the LED brightness accordingly (this part is all done in code. All the hardware has to do is what's shown in the website images above - connect a 5v wire and ground wire to the potentiometer as well as a "signal" wire in the middle, which goes to an Analog-In pin on the Arduino).

Re: Soldering -
You can just solder right onto these metal strips that you see. If the LED strands have a waterproofing coating on them (they often do), you might need to cut or peel it back to be able to get to the metal strips on the strand. If you've never soldered before, there are tutorials everywhere that are great (try youtube and instructables.com). Practice on a few non-important items before going in on your actual project.

Hope that helps!

OK, I get the picture. That certainly puts things in perspective. I think you're on a solid track but I tend to think in terms of implementation issues. Now that I understand the task, let me suggest a few things.

• Your enclosure/box for the animal. You probably already intend to use a separate manual door to place the animal inside. If not, I suggest strongly you consider having a separate (manually operated) door to place animal inside. I suspect the plastic door may need to run slowly to overcome the weight, not sure...
  
• For this type of project, I consider your limit switch approach to be fine. But looking over the actual switch, I can see it won't lend itself to hold extra wiring (like a diode, capacitor PLUS the wires). Instead, it appears you need to use special female-crimp-lugs to connect to the switch male-lugs. So that indicates the need for some kind of wiring area (a wood block or perhaps a terminal strip or a small PC board) for solid connections to be made. It makes sense to have two such wiring sections -- one proximate to each limit switch. So I think its wise to be prepared to do wiring mostly off the switches such that components (Cap, Diode) can be connected to wires and wires then sent to motor and switches.
  
• I consider the addition of the non-polarized cap to be important to protect the diodes from voltage surge (breaking connection to motor coil) and keeping the limit switch contacts from getting damaged by sparks. Think of it as the cap used in ignition systems to protect what they call "points". It should keep things reliable. You don't need a failure in the field with this type situation.
  
• Another thought, suggest you build this with an eye on being serviceable. If your project is a great success, you may be using it far more than you think you will. If that is possible, you want to have spare parts for servicing, and build the project with an eye on being able to service it quickly (for example, repair it in the field). If that is possible, you may want to evaluate your build plan to incorporate a modular approach for easy service and repair. Something to consider...
  
  So, that's my 2 cents :). When do you start construction? Do you have a plan for building the enclosure? What overall weight are you envisioning I wonder.
  
  hth

Do you think there's a market for this sort of thing? Like, if you were to sell the equivalent for $75, do you think there's enough people that would buy it to make it worth the time? Thinking about whether it would be worth the effort to make up a little version of this :)

I would be curious to see what the chip # is, as well as the 3-pin part on the side (under the grey heatsink putty).

I have a feeling what that active circuitry does is actually act as a constant current regulator to charge up the caps. The problem you will have with so much capacitance is getting a massive inrush when you first connect the power supply. Ie, the caps will look like you shorted the power supply until they reach the operating voltage. The power supply probably won't like that.

So, having said that, to answer your question about capacitance: You can try experimenting.
To start with, it looks like they have a 2200uF cap + 6 of whatever those other things are (still assuming they're flat pack caps, but they could be something else). My feeling is that they're probably some lower value to deal with some of the higher frequency components.

I would buy a selection of beefy caps, and just start putting them in parallel with the power supply. Make sure they're rated to be at least 16V!

Instead of the constant current circuit, you could have a toggle switch (make sure it's rated to at least 1.5A) in parallel with a 1-ohm power resistor.

When you want to connect power, you have the switch in the open position, then connect the power supply. Wait maybe 10 seconds, then flip the switch to the bypass / shorting position to remove the resistor from the circuit. At that point, you can use the camera.

Something like this:

https://imgur.com/a/5VgBx

EDIT: screwed up on power jack, more like this: https://imgur.com/a/00ujw


EDIT2: You can also buy constant voltage / constant current power supplies. Lab power supplies are an example. They won't care if you short the output; they'll happily limit the current to whatever they're set to. Actually, most wall adapters have a similar "anti-short" protection of some sort built in, so you might be able to get away with not using the switch / resistor trick.

You could buy something like this: https://www.amazon.com/Eventek-KPS305D-Adjustable-Switching-Regulated/dp/B071RNT1CD/ref=sr_1_5?ie=UTF8&qid=1523427142&sr=8-5&keywords=lab+power+supply

I have been crimping connectors like this to all my wires for a long time now and it is awesome. Fair warning though, it's definitely something that takes practice and will be slow going until you get the hang of it.

The benefit though is that something like this will last you a LONG time and being able to make all your projects modular is a huge bonus.

Also, depending on the wire you are using, you may not even need to strip the ends once you get comfortable. Most of the time the wire I use is small enough that even the insulator fits within the connector and crimping it drives it through the insulation to make solid contact.

Beauty!

Potential eventual fire hazard? Maybe.

But a beauty nevertheless!

Constructive criticism: Try not to have floating resistors like the three or four near the righthand side. I understand you were running thin on both board space and lanes -- I suggest using a perfboard where the perforations are not connected, such as these:

https://www.amazon.com/AUSTOR-Including-Double-Prototype-Connector/dp/B07CK3RCKS/ref=sr_1_4?keywords=perfboard&qid=1562508877&s=gateway&sr=8-4

You can connect separate holes by bending the excess wire on your components, or, where necessary, by bridging the separated pads using solder.

An added bonus is that these also contain screw terminals which will offer a more serviceable way to connect your wires.

You will need to drill holes for mounting screws, of course, but this is doable. You can also manually cut between the rows using flush cutters if you want to cut a board that is too large down to size. This is a good way to maximize space usage.

GLHF!

It really is a neat box. I would love a wall wart that looks like that.

> Hey guys, I'm a self-educating DIY electronics fan (not yet too experienced) and I am going to be a volunteer on a makers fair with a goal to lead a workshop for about 40 kids.

> Time: 60 minutes, Budget: about $4, Difficulty: complete beginners, Age: 11+

Fuck, dude. 40 kids, on a $160 budget, all at once... that's a tough ask and it's gonna suck. That's a ton of kids.

I TA'd college sophomores for E&M lab- around 40 kids, 3 hours. You'd be amazed how little progress people make if they're just a little too confused. Even with parents there it's gonna be very hard to get everyone the help they need in one hour, and I'm gonna assume you don't have 40 soldering irons (or even 10-20). If 5 parents have never heard of a soldering iron, 5 more won't pay attention, and 5 will somehow end up grabbing it by the hot end. Anyway, you'll probably want to buy a bunch of mini breadboards. They can also reuse it for other things. Remaining budget: $3.16.

Speaking of reusability- given passives are so cheap, I'd buy plenty extra and give them a goodie bag with a resistor chart and maybe even some basic formulas and diagrams. That way they can keep experimenting at least a little. Generally, I think kids should be using passives and maybe op amps. BJTs are just too hard to use without math, and even 555s are pretty complicated for an 11YO. NAND gates are simple conceptually, but even a large percentage of grown-ass adults in a workshop are gonna lack the focus to figure out which of the 8 indistinguishable pins is the right one to wire up to the other indistinguishable pins. So I'd avoid adders as well, unless they're pre-wired.

Passives at DC are boring. Sorting resistor values is boring. You've gotta try pretty hard to overcome the first and minimize the second. I'm not sure how nerdy and boring this is, but I think one neat idea would be to make an LED controlled by a resistor ladder ADC. It'll require some pretty talented explanation, but if you can successfully do that and build the steps to make it obvious the voltage is halved each time, you're literally showing them how binary works. They can see that and know how a computer translates a binary number into an actual value. You'll have to actually test resistor values to see what visibly changes the LEDs resistance, and it might be better to label the different ladder points by 10s instead of 2s (ie 1 + 10 + 100 + 1000).

I don't think you have enough time and even if you open by stressing that wall voltage will kill you parents may not be a fan of high voltage, but one more complex but way more stunning example would be a Cockroft Walton multiplier. For $2.50 per kid you can get an 18 V supply, which you can turn into AC with a 38 cent LM324N or similar set up as a multivibrator. The remaining 28 cent budget isn't enough to get 5 stages worth of resistors, capacitors and diodes, but if you can swing that then that's ~140 V at the output, and I think it should be able to produce a visible but basically safe arc. It will destroy pretty much any electronics it gets near though. Also if you really tried to get them to understand how it all worked, a multivibrator is like an hour on its own and a doubler cascade is probably another 90 minutes.

Aside from those two I'd try to go for lights (sound would just be cruel to parents) and interactivity. Also, it's too expensive and too slow for this, but NB that conductive epoxy exists- it's actually low enough resistance that you can use it to pass small amounts of current through glued joints.

Arduino is great for plug and play, blink an LED, using code. But if you want to understand electronics I would start here:
Easy Electronics (Make: Handbook) https://www.amazon.com/dp/168045448X/
^you could shoot through this book in a weekend.

After doing that book I would get this book:
Make: Electronics: Learning Through Discovery https://www.amazon.com/dp/1680450263/
You can purchase the parts individually or buy kits specifically made for the books. I found the kits will save you time.
I started like you a few years ago and now have moved on to arduino and am designing my own PCBs. Good luck.

First of all props to you to introduce your son to electronics and ask to find a good method for him to learn it out of interest.

I remember having electronics kits which had a bunch of simple components connected by those metal spring terminals. They often came with booklets to go step by step through simple projects to gain some understanding.

Perhaps you could look at toy shops and see if they carry some educational electronics kits? I remember book shops also sold them though I'm not sure if they'd still.

I found this on Amazon, seems a bit different with magnets snapping together but looks like it goes step by step in explaining: https://www.amazon.com/Snap-Circuits-SC-300-Electronics-Discovery/dp/B0000683A4/. Looks a bit expensive but not sure if that's different in the US.

Oh boy I even found one of those kits with the spring terminals: https://www.amazon.com/gp/product/B00000IUD2

Best of luck!

This is great info. I am really pretty new to any kind of voltage smoothing, voltage regulation, current regulation. Is there any source you would recommend to use for reference? I was planning to use something like this which has over current, over charge protection already built in. That way I could charge the battery then plug it into my phone and get out a constant safe supply my phone could use.

Edit: Also found these, which seem to be exactly what I would need. The reviews say they do a good job of cancelling input noise.

I recommend you use one of these temperature controllers. I used one to allow me to control the temperature of a small freezer to use it as a refrigerator. Another one proved to be great as a doghouse temperature controller. The thermocouple temperature probe is waterproof and sturdy. It has a built in 10-amp relay so it will handle a substantial load. It would be great for a Sous Vide project.

Have fun.

I like your setup. If you don’t have one already, Panavise makes some nice stuff. Like this:


PanaVise Model 201 "Junior" Miniature Vise https://www.amazon.com/dp/B000B61D22/ref=cm_sw_r_cp_api_i_986RDbYZT1M85


Also some version of the helping hands;”:

US $5.58 23％ Off | Helping Third Hand Tool Soldering Stand With 4X Welding Magnifying Glass led Adjustable 2 Alligator Clips 360 Degree Rotating
https://s.click.aliexpress.com/e/Ea8dD8yg

And depending on what you end up doing, a hot air smd rework might be helpful to have. I initially got one to repair my arduino after blowing out a chip on it and have found it useful for heat shrink tubing and other projects that are repair work. Especially since nothing you buy nowadays comes as a through hole board. It’s all smd.


US $25.07 41％ Off | 700W 858D Hot Air Gun Desoldering Solder Rework SMD Station Set
https://s.click.aliexpress.com/e/Bblg8Wyo

Congratulations on the wedding! I have actually just wrapped up the same project for my step-moms 50th birthday! I went a slightly different route, instead of a mouse, I used a keyboard. Instead of that done switch I used an Easy button. Instead of sparkbooth I used dslrPhotoBooth.
My plan is the same as your, press button trigger system.

I used a keyboard just like this:

I dont know the exact model. It was one I had lying around, it was also black. Point is the chip inside was small. Took the keyboard apart, grabbed a sharpie and on the top layer of the keyboard "circuit" traced from the space bar button back to the top, then moved to the bottom layer and did the same thing.

This is the button I used:
The global edition has some electronics in it, about half of you will throw away and the rest you will "modify". Basically, take it apart, take out the speaker, take out the batteries. The buttons are on the side of the selector in the middle, I soldered to one side with (two wires, then I cut the traces to the rest of the circuit (leaving the traces connecting the two buttons together).
I then soldered the two wires to the traces on the keyboard that matched the space bar.
I had to cut the traces, if you dont, you will be feeding +5v from the keyboard circuit back into the easy button circuit and you will get weird results.

When you put it all back together make sure you line up the button with the selector, that adds to the "button" feel so I left it in there. I was able to fit the keyboard PCB where the speaker was after I filed out some of the plastic for the battery compartment. Then I used my soldering iron to melt a hole/slot in the side and started to reassemble the button.

Software: Nothing fancy here, software is decent, does what I want/need. Is triggered off the space bar (if your software is triggered off a different button just trace that button from the keyboard, hopefully it can be triggered from the keyboard, the mouse might require the pointer to be on a certain spot.) Also there is a decent ipad app that will allow for people to see the photos and send them to themselves if they want that plus the print. I believe you can even to facebook uploads if you have setup a page for your wedding, I have only tested the email portion.

I know I didn't directly answer your question but I hope that it helps in some way.

I will post a picture tonight of the final thing. I thought I had one on my phone, guess not.

19.2 is the nominal voltage of your battery pack. Charge voltage should be aprox 23,2 or most likely 24V could be used without making much of a difference.. NiMH ideal charging can be tricky..

You could possibly replace those with Lithium chamistry but you'd need a whole new battery charger and a BMS for protection and balancing.

16 new AA NiMH like these are your best way to go I am afraid as conversion to Lithium would be better in the long run

Just gonna straight copy this from a post awhile ago. These are things that I use consistently in my engineering labs. The ones with the will probably be good for you

These are parts I use consistently in my labs
Capacitor kit


Resistor kit


Jumper wires


Bread board(s)


Larger breadboard. Recommended for larger projects but I haven’t used it too much. Best for large IC circuits


*Multimeter. This has all the right features

Other things that can be useful:


•Wire strippers


•Pliers


•Electrical Tape


•Tackle Box or tool bag (to carry everything)


•Flat jumper wires