With roots that date back to 1836, Morse code is one of the first methods of quickly communicating over large stretches of land or water. This language of sorts consists of dots and dashes or long and short sounds utilizing the Latin alphabet, generated by a key sent over the electric telegraph. It’s named for Samuel F.B. Morse, an inventor of the telegraph and Morse code.
Morse code is still widely used today across the globe by amatuer radio enthusiasts known as HAMS and by professionals in the aeronautical and aviation fields.
In this project, we blend old school and new school tech to create a Morse code oscillator that you can use to practice keying Morse code. We start by milling out a double-sided board on the Bantam Tools Desktop PCB Milling Machine, then we solder on a series of components, and finally test our skills of yesteryear communication.
Tools, Materials, and Files
- Bantam Tools Desktop PCB Milling Machine
- Computer with Bantam Tools Desktop PCB Milling Software installed
- Soldering iron and solder
- Flat end mill, 1/32”
- Flat end mill, 1/64”
- Flat end mill, 1/8"
- Bit fan
- Digital calipers
- Flush cutters
- Power source, 9V
- Alignment bracket (not pictured)
- Printed circuit board blank, FR-1, double-sided
- Resistor, 15K (2) Brown-Green-Orange
- Resistor, 10K Brown-Black-Orange
- Resistor, 4.7K Yellow-Purple-Red
- Resistor, 10-ohm Brown-Black-Black
- Capacitor, 0.01uF (2) Marked 103
- Capacitor, 0.047uF Marked 473
- Capacitor, 2.2uF Polarized electrolytic
- Capacitor, 10uF (2) Polarized electrolytic
- Capacitor, 0.1uF Marked 104
- Capacitor, 100pf Marked 101
- Capacitor, 470uF (2) Polarized electrolytic
- Potentiometer, 10K
- Transistor, 2N3904
- IC, LM386
- Screw terminal, 2-pin
- Headphone jack, 1/8" (3.5 mm), through-hole, PCB-mount style with 3 leads
- SPST slide switch, 3-pin
- Barrel jack, 5.1 mm, PCB mount
- Double-sided tape
- Isopropyl alcohol
- Wire (2 pieces)
- Morse code key
Download the Morse Code Oscillator EAGLE .brd file.
Step 1: Gather your supplies.
Get your tools and materials ready to go. Make sure you have the latest version of the Bantam Tools Desktop PCB Milling Machine Software installed on your computer. Fire up your computer and your Bantam Tools Desktop PCB Milling Machine.
Step 2: Mill the board.
- Download the Morse Code Oscillator .brd file into the Bantam Tools Desktop PCB Milling Software.
- We’ll be milling a double-sided board. If you haven’t milled a double-sided board before, please check out our tutorial.
- Attach a single layer of double-sided tape to one side of the board, and measure the thickness of the board plus tape. Align the board, tape side down, to the home position, in the left front in the alignment bracket.
- Set up your material by selecting Double-sided FR-1 in the software. This should be 5”x4” and the measured thickness.
- In the imported plan window, make sure the top layer is selected.
- Select the Traces and Hole option for the top layer. Deselect Outline.
- In the milling tools sections, choose 1/64” flat end mill in the first drop-down menu. Add 1/32" flat end mill to the second drop-down and 1/8" flat end mill to the third.
- Start with the 1/64” flat end mill.
- In the Advanced tab, change the trace clearance to 1”. This will mill out everything but the traces.
- If everything looks good, engage the cut.
- The software will prompt you through the tool changes.
- When the top layer is complete, very carefully remove the board with isopropyl alcohol and a scraper. Remove the double sided-tape and wipe dry.
- After the board is dry, apply a layer of double-sided tape to the milled side of the board.
- Align the board to the right side of the bracket. The holes should be closest to the right front of the bracket.
- Select the bottom layer of the board in the software. You should see the new layer show up in the preview window aligned on the right side.
- Unselect the Holes tab and select the outline. Traces should remain enabled.
- Rehome the machine before doing any tool touch-off or cuts.
- Your tools will be the same as the top layer.
- Insert the 1/64” flat end mill to start with.
- Engage the cut when ready. The machine and software will prompt you through the tool changes.
- Once the board is finished, remove carefully with isopropyl alcohol and scraper.
The top of your milled board should look like this:
Bottom of the board:
Step 3: Solder the components.
Many of the through-holes are also vias. This means the components will have to be soldered on both sides of the board.
Pro Tip: Test the board with an oscilloscope or multimeter as you build it. This will help minimize any issues along the way.
Let’s start with the top layer of the board:
Solder the IC LM386.
- Gently bend the legs of the chip so they fit in the holes.
- The dot or divot on your chip should be facing the longer side of the board.
- Make sure the IC is snuggly in place and the leads are going all the way through the board.
- Solder the top side first. Flip the board over and solder the bottom leads in place.
Solder the 2.2uf capacitor.
- This capacitor will go directly to the right of the IC.
- The capacitor is polarized, and the longer lead is positive while the shorter lead is negative. The pads on the board will guide you: The square indicates the positive terminal, and the round one is negative.
- Insert the capacitor, being mindful to leave enough room to solder beneath the cap.
- Flip the board over (bottom side) and solder the leads. Clip off the excess.
Solder the 10uF capacitor.
- This capacitor will go on the top left of the board, near the IC.
- We'll only be soldering one of the 10uF capacitors. The other 10uF capacitor is just in case you need more gain. Put it aside for now.
- This is another polarized capacitor, so the square pad is the positive lead, and the round pad is the negative lead.
- Make sure to leave room under the capacitor to solder, flip the board over, solder the leads, and trim the excess.
Solder the 10-ohm resistor.
Resistors don't have any polarity and can go through the holes in any direction.
- The resistor may not lay directly down on the board. Get it as flat as you can on the board. One side will likely be raised a bit, that’s okay.
- Solder the top side, flip over, solder the bottom, and trim the excess leads.
Solder the 10K potentiometer.
- The potentiometer goes in the upper right corner of the board, closest to the IC.
- Solder the top of the board first, under the knob of the potentiometer.
- Flip over, and solder the bottom in place. No need to trim any excess.
The board should now look like this:
Solder the 0.1uF capacitor.
- This capacitor isn’t polarized, so it can go in any direction.
- Position it just under the 10uF capacitor.
- Solder it into place on the top of the board, flip over, solder the bottom, and trim the excess leads.
Solder the switch.
- The switch will go to the side of the 0.1uF capacitor, on the edge of the board.
- Situate the board at an angle with the edge of board positioned in a way that you can see the switch’s pins and can squeeze in your soldering iron.
- Solder the top side in place, under the slide switch.
- Flip the board over and solder the leads in place. No need to trim off the excess.
Solder the 100pf capacitor.
- This capacitor isn't polarized, and it'll go below the 10-ohm resistor that we soldered previously.
- Solder it into place on the top of the board, flip over, solder on the bottom, and trim the excess leads.
Solder the headphone jack.
- The jack is on the opposite side of the board from the barrel jack.
- Squeeze the leads into the holes, making sure to leave enough room to solder it into place.
- Flip the board over and solder the bottom leads. No trimming needed.
Solder the barrel jack.
- This jack will go below the switch. You’ll want to place the leads through the holes and solder it in place under the barrel.
- Make sure the board is at an angle so that you can easily access the leads for better solder joints. Using flux can also help.
- Solder the bottom of the board. No need to trim anything.
Solder the 470uF capacitors.
- These are the biggest capacitors in the bundle. They're also polarized. Make sure the positive lead goes in the square through-hole and the negative goes in the rounded one.
- These two capacitors go in the middle of the board.
- Solder them in place, making sure to leave enough room under the barrel. Flip over the board and solder the leads in place, then trim off the excess.
Solder the 2-pin screw terminal.
- This terminal will go below the headphone jack in the two larger holes you see at the bottom of the board.
- This part is a little tricky! We used an old piece of FR-1 to prop the terminal off the board, along with some painters tape to hold it in place while soldering.
- Solder under the terminal first. You may want to use flux to help get the solder to really flow.
- Once the tops side is done, flip the board over and solder the bottom leads in place. No trimming needed.
Solder the 0.0047uF and the two 0.01uF capacitors.
- One 0.01uF capacitors goes by the barrel jack and the other by the screw terminal.
- The 0.0047 capacitor sits next to the 0.01uF and near the screw terminal.
- The other 0.01uF capacitor sits by the barrel jack.
- These capacitors aren’t polarized and can go in any direction.
- Solder them into place on the top, flip the board over, solder the leads, and trim the excess.
Now let’s solder the remaining resistors.
- Start with the 10K and 4.7K resistors.
- Solder them on both sides and trim the excess leads.
- Next place the two 15K resistors in the final two spots.
- Solder these into place and trim the leads.
Finally, solder the 2N3904 transistor.
- Bend the middle lead toward the rounded side of the transistor.
- Gently place the leads into the three holes on the lower left side, close to all of the resistors.
- Solder the transistor into place on both sides, and trim the excess leads.
This is what the top of your board should now look like:
Now that you’ve done the hard part, let’s test our board. Strip both ends of two pieces of wire, and screw then into the screw terminal. These wires are not polarized and can go directly into a Morse code key, or you can simply use the wires. Plug in your 9V power and a speaker, touch the stripped ends of the wires, and you should hear the lovely tones of yesteryear.
Congratulations, you’re well on your way to learning and practicing Morse code! In the world of amateur radio, DIY rules the roost, and this homebrew project is perfect for anyone wanting a practical, fun, and engaging tool. Below is a guide to Morse code.
- Check all of your solder joints to make sure they're good. You can use a multimeter to be extra thorough.
- If your solder joints are too close, use an X-Acto blade to cut a line on the board between them.
- Make sure the polarized capacitors are positioned in the correct way.
- Double-check your board for any fine hair traces left over that might be shorting the board.
If you have any questions, we're here to help! Email us at firstname.lastname@example.org. If you build your own Morse Code Practice Oscillator, we'd love to see it! Send a picture of it our way, or tag your social posts #bantamtools to get on our radar.