语音聊天摩尔斯密码键盘

In this project you will get to build your own morse key! The morse key can be plugged into your computers microphone port and will send a beep when pressed. Morse code is one of the earliest forms of instant long range communication and can be send via any signal that can be turned on and off, be it electricity, light, radio waves, sound... Nowadays we have other means of communication that are many orders of magnitude faster and enable us to talk to each other across the globe. Despite those methods morse code is still used today when all else fails, for example to send emergency SOS (... --- ...) Signals. This project won't save you when you are stranded on a lonely island, but learning to morse may very well do.

1) Soldering

The circuit board gets soldered according to the layout. Ideally print out a mirrored version of the layout to make it easier to route the wires. While this is not a very complex circuit is not suited well for absolute beginners in terms of soldering. I'd reccomend to train on a kit with a printed circuit board first to learn the basics of soldering in components and at least attempting some perfboard routing on a scrap piece before soldering this circuit. Short pieces of the solid wire need to be soldered to the leads of the battery clip. The soldering joint needs to be protected with heat shrink tubing. The positive wire then gets stripped and bent into a loop to fit around an m4 bolt, the negative one gets stripped to fit a screw terminal.

A short overview over how the circuit works

This is a quick explanation of how this circuit works. Understanding this is not nessesary for building this project. The first part of the circuit is a square wave generator. It consists of an inverting schmitt trigger that alternates between charging and discharging a capacitor. the capacitor voltage will show a triangle wave between 1/3 and 2/3 of the operating voltage, determined by the ratio of R1, R2 and R3. This design was chosen over more popular ones like the 2 transistor astable circuit or the NE555 oscillator for a few reasons: - the frequency can be adjusted by changing a single resistor (both r3 and r4 could be used for this purpose) while maintaining a duty cycle of 50% - the second opamp in the IC is needed elsewhere in the circuit This square wave could be used as the sound as it is, but it would sound more like a gameboy beep than a morse beep. To make it more sine-ish a low pass filter is used. This "rounds off" the sharp edges of the square wave. The next part of the circuit is an impedance converter. It works as an amplifier with an amplification of 1. It is used to not change the filtering parameters of the low pass filter with the following circuitry. At this point the voltage still oscillates around 1/2 of the operating voltage. The capacitor C3 decouples the signal by blocking the DC part while letting the AC part through. The last part of the circuit is an adjustable voltage divider. Microphone inputs need to be very sensitive to pick up the small signals put out by microphones. The potentiometer is used to adjust the "default volume" and match it to the sensitivity of your input. If you can't find this component dont worry- you can replace it with a fixed value resistor and play with the gain settings in your microphone options. Anything between 300 Ohms and 1 kOhm is a good bet.

2) Building and Wiring

In this section you will find all the steps for building your morse key and setting it up for use.

Preparing the prints

The first step in actually building the morse key is cleaning the 3D printed parts and installing the threaded inserts. This can be done with a soldering iron, but it requires some pracitice. (side note: don't use your best tip for this) To help you not ruin your freshly printed parts during this procedure the files include a piece to practice on. The pracitice piece takes m3 inserts. Once you feel safe with installing inserts, install them into the 3D printed pieces: - 4x m3 into morse_body - 3x m4 into morse_lever - 1x m4 into morse_knob There are many great tuturials online for this, and even some special tools that keep the inserts perfectly straight during installation. Make sure that the morse_axle piece can rotate inside the morse_lever piece and at least fits into the morse_pivot pieces.

Preparing the wires

The 10cm stranded wire needs to have cable lugs crimped onto either side. The two long pieces get soldered onto the 3.5mm audio jack. one of them gets attached to the "GND" contact, the other one gets soldered to both the left and right "MIC" contact. MAKE SURE TO SLIDE THE HOUSING OF THE JACK OVER THE WIRE BEFORE PROGRESSING TO THE NEXT STEP The two lose ends each get a cable lug crimped onto them. If you are using only one colour of wire now is a great time to mark which end is which! As a last step the two wires get twisted together, like you would do when making a rope.

A note about style

Modern cable lugs usually have a bit of plastic shielding to prevent short circuits. This is a good thing! I used unshielded cable lugs because i wanted to preserve the old school vibe of my morse key. I also used only one colour of wire for the same reason. The risk of short circuits is very low due to the spacing of the bolts and the very limited power of a 9V battery. I would still advide against the use of unshieded lugs. Proper insulation and colour coding of wires are good practices to get used to.

Preparing the lever

To assemble the lever follow these steps: - attach one side of the short cable to a 30mm hex bolt using a nut - screw it into the matching hole of the lever, but don't tighten it. Orient it as seen in the picture - use a nut to fix it firmly into place - screw another bolt into the lever so that is sticking out 5-10mm on the other side. - use another nut to fix that screw in place - thread the knurled nut onto a third 30mm bolt - screw that bolt into the last threaded hole. - screw on the knob using the m4 flathead screw. DONT OVERTIGHTEN IT! Due to the orientation of the layers it is very easy to split the lever during this step. I would reccomend to use some glue to help keeping this part in place.

Wiring

Inside the body of the morse key are 6 holes for m4 bolts as well as a space for the circuit board and a space for the battery. Start by putting bolts through the holes in the middle of the body. The bolt closes to the front gets put through the wire loop at the end of the positive battery lead. All three bolts get fixed with a nut on the other side. Next, prepare three pieces of solid wire by putting a loop on one end and a short stripped section on the other one. Attach each one to a bolt using a nut. Stick these three bolts throug the remaining holes in the body of your morse key and fix them with another nut. At this point, when looking from the bottom, you should be left with four lose wire ends: (front end of the key pointing right) - battery negative - top left bolt - bottom left bolt - bottom right bolt Check the circuit board layout for the next step to get the numbering of the screw terminal: |terminal| attach to:| |:--- | ---:| |screw terminal 1| bottom right bolt| |screw terminal 2| top left bolt, battery negative| |screw terminal 3| bottom left bolt| Turn the morse body over to finalize the wiring as seen in the pic above: (front end of the key pointing right) |bolt| attach to:| |:--- | ---:| |top left bolt | MIC signal wire| |bottom left bolt | MIG GND wire| |top right bolt|other end of short wire|

Final assembly

To finish the assembly, stick the axle through the lever and cap it with the two pivot pieces. Glue the pivot pieces into the morse body. Once the glue is dry, install the spring. Losening the bolt and screwing the bolt out somewhat can help getting with the spring in. Losen the knurled nut and adjust the rear screw while repeatedly pressing the lever untill you are happy with the gap. Permanently set the gap by tightening the knurled nut again. Set the potentiometer to the middle position. If your input is too loud or too quiet you can come back to this step and adjust it. Check for a short circuit before installing the battery, then screw the bottom plate on using the remaining four m3 bolts. Lastly stick on the rubber feet, making sure to not cover the screw heads. Congratulations! You are now the proud owner of your very own morse key!

How to set up and use

Feel free to plug your morse key into your computers microphone port! DO NOT PLUG IT INTO YOUR PHONE! While your phones audio jack (if it still has one) has a microphone line, it also has headphone lines. If you want to use your morse key with your phone you can get a Headset Y-Splitter. This adapter seperates the microphone line from the headphone lines. At this stage, you can use the morse key to send beeps over any voicechat you want. To also hear what you are sending you need to enable "microphone monitoring" for this input. There are many tutorials out there on how to do this for different operating systems, so just give it a quick google search. Have fun morsing!

Troubleshooting

Here are some problems i encountered together with their fixes: - The beep is way too loud/quiet: You can use the potentiometer to adjust the volume of the beeps. - The beep sounds "scratchy" Try giving the contacts a few passes with some fine sand paper. Modern switches use different techniques and materials to prevent corrosion and ensure they last a long time. This switch only uses simple screws, so dust or corrosion can be a problem. Luckily the exposed contacts make fixing this very easy! If that doesn't solve your issue your battery might be running low. Try measuring its voltage or checking with a fresh one. - I can hear myself sending perfectly, but the other people in the chat cant hear me well / at all Have you selected your morse key as the input device? If this isn't the problem try turning off any speech filtering tools like Krisp. These tools are designed to seperate speech from anything "not speech", so naturally they try to filter your morse signals away. If that still doesn't help, maybe your voicechat disables the microphone when you aren't speaking. Try to set your mic to be permanently active. If that isn't an option a quick fix is enabling push to talk and placing something heavy on the key.

Tools required

To build this project you will need access to a 3D-Printer as well as basic electronics tools such as a soldering iron and crimping pliers. If you aren't sure if you have all the tools required, just read through the instructions and see if there is anything missing. If you dont have the tools for a specific step or need help in general, try visiting your local makerspace!

Printed parts

colour suggestion: black - 1x morse_body - 1x morse_base - 1x morse_knob - 1x morse_axle colour suggestion: silk metallic - 1x morse_lever - 2x morse_pivot All parts are prepositioned for printing and dont require support. morse_knob and morse_axle work best with some brim added to increase bed adhesion. If your printer supports it, morse_knob greatly benefits from adaptive layer height.

Mechanical hardware

- 8x m4 x 30mm hex bolt - 1x m4 x 16-20mm flahead bolt - 4x m3 x 10mm flathead bolt - 1x m4 knurled nut - 18x m4 hex nut - 4x m4 x 8.1 x 6.3 threaded insert - 4x m3 x 5.7 x 4.6 threaded insert - 4x self adhesive rubber foot - 1x spring

Electrical hardware

- 4x ring cable lug (for m4 bolts) - 1x 9V battery clip - 1x 3.5mm audio jack - 1x stranded wire ~ 10cm - 2x stranded wire (chose the length you want for your output wire) - solid wire ~ 30cm in total (this will be cut to length for the internal wiring) - shrink wrap tubing appropriate for your wire size - 1x 9V Battery

Circuit Board BOM

- 1x piece of perfboard - some wire for routing | Component | Value | | :--- | ---: | | C1, C2 | 100nF | | C3 | 1µF | | IC1 | LM358 | |R1, R2, R3, R4, R5|10k| |R6|3.3k| |R7|1k Pot| |X1|Screw terminal 3 pin|

Morse code reference

| Letter | Morse code | | :--- | ---: | |A|.-| |B|-...| |C|-.-.| |D|-..| |E|.| |F|..-.| |G|--.| |H|....| |I|..| |J|.---| |K|-.-| |L|.-..| |M|--| |N|-.| |O|---| |P|.--.| |Q|--.-| |R|.-.| |S|...| |T|-| |U|..-| |V|...-| |W|.--| |X|-..-| |Y|-.--| |Z|--..| | Number| Morse code | | :--- | ---: | |1|.----| |2|..---| |3|...--| |4|....-| |5|.....| |6|-....| |7|--...| |8|---..| |9|----.| |0|----|