5050 SMD (Surface Mount Device) LED Demo

Learn a little about a 5050 SMD (Surface Mount Device) LED. See my test bed and how I test warm white and cool white 5050’s.

They’re called 5050 because their dimensions are 5.0 x 5.0 mm. They operate at 60mA, 3V to 3.2 Volts. In my video I show that there are actually 3 LEDs in each 5050 package. So you could just light one or two of those and only use 20 or 40 mA if you want to reduce the current used.

I get the 5050 LEDs from Amazon here: http://amzn.to/2DlgjAD

Here’s a link to the copper tape: http://amzn.to/2CSrCzk

Digital Calipers: http://amzn.to/2BR4MZ0

I get my alligator clip test leads locally, but these look pretty good if you need to order online: http://amzn.to/2FvuIeu

I have several of the battery holders with a built-in current-limiting resistor and on/off switch. Let me know if you’d like to purchase one for $3.95 and free shipping.

 

Basic Arduino LED Circuit

A short video showing how to extend a simple circuit out from the Arduino.

Here’s a source for breadboards on Amazon: http://Amazon: http://amzn.to/2CHpeLK

You can get a set of 3 Arduino Nanos here: http://amzn.to/2mbrbsG .  You can’t beat the price of these Chinese clones, but know that you will need to solder the headers on,  and you may need to download a driver for these Chinese clone boards. See how I do that in my video here: http://mechatronicsworkshop.com/index.php/2017/12/14/arduino-nano-prep/

You can purchase clones with the headers already soldered on if you search for them. Be careful buying clones — these appear to come from a warehouse in the U.S. so shipping is quite fast to the U.S.  But be careful that you don’t buy them from  a supplier who ships from China unless you or ok waiting for three to four weeks to get them delivered.

If you want to pay more and have the headers soldered on and no need to download a driver, go to the Arduino.cc site and purchase the original boards there.

Elenco is a great company to find larger breadboards, and all sorts of fun electronic stuff: http://amzn.to/2maSIun

 

 

 

The L298N H-bridge motor controller module basics

Oh boy, was I confused about this module at first! I found a fair amount of bits and pieces about it, but could not find the complete info that I was looking for. So I decided to create this tutorial for others who want to understand it better. I’m not an expert, but I have figured it out well enough to make what I think is a very clear and complete basic ‘primer’ on this device. Whether it’s right for your project is up to you to determine, but here’s info about the module itself, and especially about the mysterious jumpers (at least they were the biggest mystery to me).

Get an L298N module at Amazon here: http://amzn.to/2CGAhVq

You can see the data sheet on their website here: http://www.st.com/en/motor-drivers/l298.html .

You could just purchase the chip and component parts and wire up your own parts, but this complete module is probably cheaper than the combined parts, and it’s certainly more convenient. As of January, 2017, the modules are selling on ebay for under $2.00! At this price they’re from China of course, but you can purchase them at higher prices in the United States if you can’t wait for the long shipping times from China.

I’ve read in forums that the L298 chip is about 15 or 20 years old, so there are better(?) chips available now. People seem to like the Pololu A4988 https://www.pololu.com/product/1182 .  Stepper motor current limiting is apparently one of the big improvements, but none of the current-limiting chips come in this neat module format that I’m aware of. So this L298N module is fun and handy, certainly great for testing and little projects, but be careful if you need current-limiting features when driving stepper motors.

 

 

Arduino Nano Prep

You can get quite a variety of Arduinos. My favorite is the Nano. Here’s how I get them ready for my projects.

Here’s a source for breadboards on Amazon: http://Amazon: http://amzn.to/2CHpeLK

You can get a set of 3 Arduino Nanos here: http://amzn.to/2mbrbsG .  You’re going to want more than one for more projects, and you’ll probably accidentally destroy one or two of them by connecting the wrong wires, applying too high of voltage, etc.

You can’t beat the price of these Chinese clones, but know that you will need to solder the headers on,  and you may need to download a driver for these Chinese clone boards. See how I do that in my video here: http://mechatronicsworkshop.com/index.php/2017/12/14/arduino-nano-prep/

You can purchase clones with the headers already soldered on if you search for them. Be careful buying clones — these appear to come from a warehouse in the U.S. so shipping is quite fast to the U.S.  But be careful that you don’t buy them from  a supplier who ships from China unless you or ok waiting for three to four weeks to get them delivered.

If you want to pay more and have the headers soldered on and no need to download a driver, go to the Arduino.cc site and purchase the original boards there.

How to Make a Rotating Head

Here’s a short video showing how to make a simple rotating head. It’s a silly little project, but it’s fun and it’s easy. If you’ve got kids interested in this stuff, it’s a great project to do with them. Or use it yourself to learn how to create and use a prototyping box of some kind (cardboard, plastic, metal), mounting and wiring a motor, and so on.

Maybe just be happy that you built a cute little toy — or get more sophisticated with the idea. You could cover the box completely with black and maybe mount and shine a little LED spotlight on the rotating head for a scary Halloween prop! (Similar to the LED spotlight on my swaying spider project. You could even add a motion-sensing switch to have it start when somebody comes near it.

You could expand on this even more and learn how to use an Arduino and a motor controller to make the head spin in both directions, or add a sound card and speaker to add some peculiar sounds!

 

Click the photos below to get the parts mentioned in the video.

Digital Calipers

A digital caliper is a great tool to have around for all kinds of measurements. An example of how I use the caliper: When I want to use LEDs in one of my projects, I like to find a drill bit just a little smaller than the LED without drilling a bunch of trial and error holes. That way the LED will be a nice pressure-fit in the hole and won’t need to be glued into a hole that is oversized.

Here are some at Amazon: http://amzn.to/2BR4MZ0

Arduino project with blinking button, siren and LEDs

A fun little project idea that tempts potential ‘victims’ with a blinking button that says, “Do NOT Press This Button!” When pressed, it sets off a siren and blinking LEDs. Let’s see who can resist!

I think it’s better to hide the cable that connects the button to the LED box. I just used what I had handy to cover the cable — two Christmas toys I had nearby. I would use something more appropriate if this was going to be anything more than a quick test setup. Wireless would be the best… maybe next time.

If you’re an Arduino fan, here’s a little side note about the LEDs. It was necessary to blink the LEDs using millis instead of delay so the button LED, the siren, and the different blink rates of the LEDs all worked at the same time.

Tin snips make terrific heavy-duty scissors

This style is officially called aviation snips. Actual tin snips are a little different but I like this style better. It has corrugated blades and leverage linkage to the blades that tin snips don’t have.

I have arthritis and cutting thicker things with scissors such as cardboard or heavy cloth, or yes, even tin, is difficult for me. I researched electric scissors but didn’t find anything that looked right. And the heavy-duty ones cost around $100.00 and I wasn’t about to spend that kind of money on scissors.

So I figured I’d try tin snips. Eureka! I love them for all of the above! They even just cut some hard plastic tubing that I didn’t think would work, but the tin snips went through it very easily. It’s easy now for me to cut all those thick things that used to cause me so much trouble. If you are having trouble cutting things, arthritis or not, get yourself some tin snips!

You can probably get them for under $10.00 and they’re fantastic! There are ‘straight cut’ style, and left cut and right cut style snips. Straight cut are best for straight-line cuts and all around use. Left cut make it easier to cut arcs to the left, right cut, easier to cut to the right. I didn’t want to be limited by a directional bias so I bought the straight cut and they’re working great!

I say “no thank you!” to ads like this one for wimpy scissors at really high prices now that I’ve discovered my tin snips!

O-ring Drive Belts vs Rubber Bands

For a long time I considered ‘o-ring’ to be the proper terminology for a drive belt in little DIY (do it yourself) animatronic projects. But when trying to purchase some o-ring drive belts, I discovered that the term ‘o-ring’ by itself is technically wrong. O-rings are for sealing things (like valves).

Better terminology when using them to drive things (transfer power from one location to another) is ‘o-ring drive belt’, or even ‘urethane belt’, which most o-ring drive belts are made from. (Rubber bands are made from, well, rubber). (So if you’re searching Google or YouTube for information on o-ring drive belts, you’ll have much better results using the full term instead of just searching for o-rings).

Rubber bands are for holding things together.

Rubber bands do not make great o-ring drive belt replacements, but they can work OK in simple applications.

How to quickly tell the difference between o-rings and rubber bands: O-ring cross-sections are typically round and they stretch some, but not as much or as easily as rubber bands. Rubber bands typically have rectangular cross sections and stretch easily.

Imagine that you have a little hobby toy your are playing with and you are trying to rotate a shaft that is located a few inches away from your drive motor.

If you use a rubber band as the drive belt, the rubber band can ‘store’ energy as it stretches, and then it will finally transfer the power (rotate the shaft) after it has stretched to a certain point. This can make for a very uneven rotation, or it might just slip on the drive or driven shaft before ‘giving up’ its energy and result in complete failure to rotate the shaft at all.

The o-ring drive belt doesn’t stretch like the rubber band so rotation is much smoother. It also maintains its integrity much, much longer than rubber bands, which loose their strength and elasticity fairly soon.

White rubber band, black o-ring shown below.

 

Here’s a little video I made to show the difference in drive smoothness:

Here’s a page with some good information: http://www.applerubber.com/seal-design-guide/special-elastomer-applications/drive-belt.cfm

And here: http://www.durabelt.com/rubber-band-belts.php

 

Got my Monoprice Select Mini 3D Printer Today

There are lots of great reviews of this one on you to youtube. I’ve been dying to get into 3D printing for quite some time and I decided to take the plunge with this one. The most appealing thing to me was the price 🙂

Is it possible to get a reasonably good printer for $200?!

Well, I was foaming at the mouth in excitement to get this — two months later I’ve barely touched it. I’ve actually found a couple of better solutions than the parts I was going to print, and I’ve been keeping busy with other things. I hope I’ll use it more soon…