When you buy electronics, they rarely come as bare PCB. For various reasons, the PCB is in an enclosure. So in this instructable, I'll show how you can take an idea and turn it into a product(ish)!
SMD soldering can seem daunting, but I promise you, this is EASY.
To follow along, you'll need the following components:
- 0805 resistors (180, 100k & 470k)
- 0805 capacitors (1uF, 0.01uF & 0.001uF)
- The robot: https://www.aliexpress.com/item/Creative-Bronze-Ne...
- CR1616 batteries
- A bit of aluminum foil
- 0805 LED (pick any color you like)
Tools that you'll need:
- Soldering Iron
- Blu Tack, Sticky Tack (what ever brand)
- Decent lighting
- A steady hand
Feeling adventurous? Build/Choose your own enclosure. The main idea here is to move away from the "circuit-in-an-altoids-tin". Don't get me wrong, THEY'RE COOL.. but almost always look pretty homemade.
I have included the eagle files, So you can change and rearrange the components and board outline.
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Step 1: Visualize Your End Product
Robots rule, we can all attest to that.
So when my girlfriend bought me this watch, I knew, I had to mod it.
With a small frame, some cavities and a pinhole, there is a lot of possibilities.
Various ideas came to mind, but I kept circling back to a simple "Beginners circuit". Something intro-level electronics hobbyists could tackle.
It had to be pure hardware, no software config. So no microprocessors. (Bye bye Arduino).
Since I got this from my girlfriend, I decided to make it somewhat romantic. Instead of keeping time, I wanted the robot to have a pulsing heart. The open glass front, also lend itself to show people, that whoever wears it, knows something about electronics. Pretty great conversational piece.
Venturing on your own path?
Try and reuse the circuit in the next step, but fit it into something different.
- Pick an enclosure.
- Measure the outline of the inner spaces.
- Consider limitations in all 3 dimensions.
- Remember to take batteries or power supplies into account
- Add/remove parts to the circuit.
- Change board outline and perhaps parts placement
Sparkfun has a pretty great EAGLE tut. in case you wonder How outlines are changed: https://learn.sparkfun.com/tutorials/using-eagle-b...
Step 2: Circuit Du Solder
Oui Oui, l'électronique est magnifique! (Sorry, I'm not french)
This instructable is a bit of a "Getting Started" and had nothing says "Hello World" as a NE555 timer blinking a LED.
Let's Give this Robot a heart!
I won't cover 555 theory, because the Internet (and Instrucables) has abundant information regarding that chip. Just look up https://www.instructables.com/howto/555/
For example, you should take a look at Alex' instrucable, pretty cool project: https://www.instructables.com/id/SMD-555-Timer-Pia...
This circuit basically puts the 555 timer in astable mode, triggering the LED On/Off at constant intervals.
You want it to go faster/slower? Put in a potentiometer. Find calculations here: https://www.electronics-tutorials.ws/waveforms/555...
My C2 cap, can be omitted, saving you a few cents.
Note, I write +5V in the schematic, but this circuit can run of a large interval of voltages.
Step 3: Get Your PCB
I am in no way affiliated with JLCPCB, but like their prices and website.
You can ofcourse use someone closer to you here is a small list:
https://www.eurocircuits.com/ (tried them before, great service)
Ordering from their site is pretty straight forward, and cheap! I've included the drill and gerber files.
You can ofcourse make the PCB yourself:
Here are two good etching instructables:
In case you make changes to the .brd file, it's easy to make EAGLE output new gerber files.
JLCPCB has a quite simple and nice explanation of how it is done: https://support.jlcpcb.com/article/43-how-to-expor...
Step 4: "Come a Litte Enclosure to Me"
This robot is cute. Let's gut it!
Removing the back, can seem difficult. You can always buy one of these: Watch Back removal tools
Or.. Use a trusted pair of pliers. They'll scratch and likely ruin the surface finish - so don't try this on your dads expensive watch. Save the white retainer, we'll need that for later.
Clock mechanism and face plate, can be discarded - or saved for other projects.
Step 5: Assembly: Soldering
I have a IFIXIT repair kit, and the parts tray is pretty great for organizing SMD components.
Finding all components, and marking them is a good way to start out. That way, you can focus on soldering, once the iron is hot and ready.
Also, I can really recommend to get a SMD resistor/capacitor kit. It wont have all values you need, but as a "getting started" with SMD, it really helps build up your lab for cheap. I got one of these
- Use the Blu Tack, to hold down the print. That way, it wont skit around on your desk.
- For each component, put a small amount of solder on one pin on the PCB.
- Start with the inner components, and work your way out. (Remember, the LED has polarity: Check LED polarity
- Place one item, reheat solder on one pin. Now its tagged down, solder the rest of the pins.
- Ones all parts are soldered down, inspect the solder joints. Take a multimeter, and check for continuity. Resistors should show their resistance value, capacitors shouldn't show continuity.
Step 6: Assembly: Putting It Together
Once you have tested, and found that the circuit works.
You can start assembly of the Robot.
BUT Try and put the parts together, you'll see white retainer rise above the robots back. To make the white battery retainer fit, you have to cut it down in height. I used a sharp knife, scissors will also work fine. A small piece of tape, will fixate the top battery, in case you cut the white retainer too much. No worries.
Remember to orient the batteries correctly. Minus towards the print, and positive outwards.
Use a small piece of aluminum to connect the front with the positive pole. To secure it, put a small amount of glue on it.
Attention: The foil is not strictly needed. I originally designed the PCB, so that it uses the enclosures conductivity.
Step 7: Aaand You're Done!
Congratulations, you've made your first Robotic Heart!
Runner Up in the