Tag: soldering

Simple & Modular Wearable Lights

jenfoxbot

Build fabulous, futuristic, and adjustable wearable lights with just a few inexpensive (and deliverable) parts! Attach to to all sorts of accoutrements and swap out colors to match outfits/feelings/holidays/all the things!

Difficulty: Beginner+

Read time: 5 min

Build Time: 30 – 60 min

Cost: ~ $5

Materials

Tools

  • Safety Goggles!
  • Soldering iron and accessories*
  • Waterproof epoxy or superglue
  • Wire strippers
    • Scissors will also work just be careful to avoid cutting the wire.

*Unable to solder? Follow instructions but instead of soldering, tightly wrap and twist bare wire connections together, then wrap tightly with ​​conductive nylon fabric tape.

Setup!

  1. Turn on the soldering iron.
  2. Remove about 1/2″ (1cm) or the plastic coating on each of the female JST connectors.
  3. New to LEDs? Test ’em out!
    • Grab your coin cell and one of your LEDs.
    • With just those two pieces, explore how to make the LED light up!
    • Hint: Read the coin cell battery. How many sides does the battery have? How many legs does the LED have?

Make the first connector!

For all steps, be sure the coin cell is NOT in the battery holder.

Step 1: Solder your first resistor to the negative ( – ) hole on the coin cell battery holder.

  • With the switch facing you, use the negative hole on the left side of the holder.
  • Pro Tip: Wrap the resistor wire around the hole, getting the resistor body as close to the hole as possible. Use the soldering iron to heat the joint for about 3 seconds, then add solder to fill in the hole.

Step 2: Grab your first JST connector and solder the black wire to the other end of the resistor.

  • Pro Tip: Wrap the JST connector bare wire around the resistor leg as close to the resistor body as possible.

Step 3: Solder the red JST connector wire to the positive ( + ) hole on the battery holder.

  • With the switch facing you, use the positive hole on the left side of the holder.
  • Pro Tip: Wrap the JST connector bare wire around the hole Use the soldering iron to heat the joint for about 3 seconds, then add solder to fill in the hole.

Make the second connector!

Repeat the same process as for the first light, but using the right-side holes on the battery holder.

More details:

For all steps, be sure the coin cell is NOT in the battery holder.

Step 1: Solder your second resistor to the negative ( – ) hole on the coin cell battery holder.

  • With the switch facing you, use the negative hole on the right side of the holder.
  • Pro Tip: Wrap the resistor wire around the hole, getting the resistor body as close to the hole as possible. Use the soldering iron to heat the joint for about 3 seconds, then add solder to fill in the hole.

Step 2: Grab your first JST connector and solder the black wire to the other end of the resistor.

  • Pro Tip: Wrap the JST connector bare wire around the resistor leg as close to the resistor body as possible.

Step 3: Solder the red JST connector wire to the positive ( + ) hole on the battery holder.

  • With the switch facing you, use the positive hole on the right side of the holder.
  • Pro Tip: Wrap the JST connector bare wire around the hole Use the soldering iron to heat the joint for about 3 seconds, then add solder to fill in the hole.

Test and Secure Joints

Step 1: Trim any excess wire.

Step 2: Insert the coin cell battery into the holder and move the switch to the “ON” position.

Step 3: Insert LEDs into the JST connectors so that the longer (positive) LED leg plugs into the red wire of the JST connector.

Step 4: Check to ensure that the LEDs light up! If it does, proceed to Step 4. If not, follow the troubleshooting guidelines below.

Step 5: Remove the battery, then thoroughly cover all exposed solder joints with epoxy or super glue and let dry in a safe, out-of-the-way spot. Remember to glue the back of the battery holder!

  • Be sure to glue the connections between the JST connector and resistor. Coat the positive and negative solder holes, but DO NOT cover any other parts of the holder or it may be impossible to insert the battery or use the switch.
  • Check the dry time for your glue (mine was about 60 minutes until fully dried). Be sure to avoid bumping or getting hair on your project, as it will be hard to remove after (as a dog owner this is a constant challenge!).
  • Pro Tip: Use a fine-tipped brush or skewer to add the glue.

Troubleshooting:

  • Check the power. The battery should be inserted so that the positive side (with the writing) is facing up.
  • Double check the LEDs are inserted in the correct orientation: longer leg to positive (red) wire, shorter leg to negative (black) wire.
  • Gently wiggle your solder connections. If you notice the LED flashes on, it is likely a poor solder connection.
    • Remove the battery and add more solder to your joint.
  • Check that the solder joints are not shorting the battery holder. If you feel the battery getting warm, this is likely the culprit
    • Check that the solder is contained to the positive and negative holds ONLY. It should not be touching any other parts of the holder, especially any exposed metal.

Finish & Flaunt!

Finally, grab your attachment mechanism and, if needed, glue to the back of the battery holder and let dry (I used a magnet for mine so no glue necessary!). Insert your preferred LEDs and attach your light-up accessory to your clothes or hair for some futuristic flourish!

Going Further

  • Sew somethin’ pretty to go over the lights!
  • Aside from hair, explore different options for diffusing the LED light. Some quick, inexpensive options are ping pong balls, a dab of hot glue around the LED bulb, or white fabric.
  • More lights!! Test before doing this as the brightness of the lights will change depending on whether you connect them in series or in parallel.
  • Add a dark detecting circuit so your lights only turn on in the daytime!
    • You can harvest a dark detecting circuit from a solar path light.
    • Or search online for the circuit!

Questions? Ideas? Let me know! I’d also love to see your finished creations, so please share!

Using an Oscilloscope!

jenfoxbot

Visualize all those mysterious electronic signals with an oscilloscope!

Learn how to build and use a super simple $30 oscilloscope perfect for electronics hobbyist applications. It’s also a great way to get started using some of the fancier oscilloscopes!

Reading and Changing the Oscilloscope Display

Every oscilloscope has a window that displays the voltage output of your signal. On every display, the y-axis is voltage, and the x-axis is time.

You can zoom in and out of the display grid by adjusting the “Volts per division”* or “Seconds per division”.

On this oscilloscope, the voltage adjustment switches are on the left side (bottom two switches), and they let you zoom out to as much as 5 Volts (“V”) per division, and zoom in to 10 mV per division.

Adjust the time scale using the “+” and “-” buttons on the right side.**

*”Per division” means the size of the squares, e.g. 1V per division means that each square is 1V in height, 1 second per division means that each square is 1 second wide. 

** Be sure that the time scale is selected (will be highlighted with a box around it — this is the default selected setting, change settings using the “sel” button, described in more detail in the next section.

Other Basic Features 

This oscilloscope has all the expected features of larger, more expensive ‘scopes, and also is a great introduction to some of the more complex versions.

On the left side, the top switch allows you to choose between a ground signal, a DC signal, and an AC signal. On the right side of the oscilloscope are four buttons:

1. The “ok” button (very top button): Pushing it once takes a snapshot of the screen, which can be saved to the oscilloscope. Holding this button down displays key numeric values about your signal, like the maximum and minimum voltage, signal frequency, etc.

2. The “+” button: Similar to an up arrow key, pushing this button allows you to sort through options.

3. The “-” button: Same as the + button, but, you know, scrolls down

4. The “Sel” button: Pushing this button allows you to select different features (described in order):

A. Change the time scale.

B. Set how the oscilloscope display refreshes – “Auto”, “Norm,” or “Sing”. More on these in the next section.

C. Set the trigger slope. More on this in the next section.

D. Change the trigger level. More on this in the next section.

E. Adjust the horizontal position of the oscilloscope display.

F. Change the vertical position of the display.

 

Oscilloscope Trigger

Oscilloscope triggers cause the oscilloscope to display a signal. Triggers are set at a specific value, or “trigger level,” along a specified direction, or “trigger slope” (more info below).

The trigger helps to display the exact electrical signal that you want, so that you get a stable display and measurement. In this ‘scope, the trigger is set on the right side of the display and the LED at the bottom flashes when the trigger is detected.

The simple oscilloscope in this tutorial has three trigger modes that you can switch between using the “+” and “-” buttons:

  1.  Automatic (“Auto”): Display continually refreshes, regardless if triggers are met.
  2.  Normal (“Norm”): Display only refreshes if the trigger is met.
  3.  Single (“Sing”): Same as normal mode, waveform display is held after a trigger has been detected.

More on Trigger Level and Trigger Slope!

The Trigger Level is a set, internal voltage that is compared to the signal, or input, voltage. The oscilloscope triggers when the signal voltage is equal to the trigger voltage. If an electronic signal rises and falls, then the trigger would happen twice: once when the signal is rising and again when the signal is falling. The trigger slope lets you choose which voltage (rising or falling) to trigger on.

 

Connecting a Component!

Now, to see the electrical signals at work in the world around you, connect the black lead to ground, and the red lead to the part of the circuit that you want to measure the voltage.

 

For example, if you want to measure the voltage output of a sensor, like the capacitor in the photo to the right, you want to connect the red probe after the sensor.

 

You may also want to calibrate your scope using the on-board signal. See the datasheet for more info.

 

Finally! Turning on the DSO138 Oscilloscope

The an oscilloscope kit in this tutorial takes about 2 -3 hours to assemble (instructions here), but is definitely worth it because many reasons! Here are a few: It’s a great way to learn circuit components, get familiar with schematics, and practice soldering (and de-soldering….). And, honestly, it’s pretty relaxing.

Once you’ve got the ‘scope assembled, it needs 9V and about 0.1A. There are two power ports: a barrel jack and a male JST connector. You can use a 9V battery with the barrel jack (OMG it’s portable!), or a power supply with the JST connector.

The exposed wire on the top of the oscilloscope is a square wave signal to help you calibrate the signal (see the datasheet for more info).

Be sure to use less than 12V or you risk heating up the board and possibly damaging it (don’t let the black smoke out!).

 

Plug and Play!

Now you know all the basics to connect your oscilloscope to sensors, your tongue, and other low power sources to watch the wonderful world of electricity at work!

Please leave a comment in the tutorial if you have any questions or would like more info about the oscilloscope kit. Now go forth and explore all that electricity! 😀

Interested in building a capacitive touch sensor like the one used in this tutorial? Check out this tutorial!