Instead of using a counter-controlled, pushbutton-activated range switch, you can use an optical encoder. Inexpensive encoders are available, and they occupy minimal space on the front panel of an instrument. Moreover, an encoder gives you the opportunity to select the optimum operating speed. However, at positions near the transition points in counter position, mechanical shocks can provoke false switching. The circuit in figure above overcomes the false-switching problem. source

The circuit is configured in balancedline mode. To reject common-mode noise signals, a balanced differential amplifier input is used. The circuit also provides an excellent bridging interface across a properly terminated telephone line. Transient protection may be achieved by splitting the input resistors and inserting zener diodes (ZD1 and ZD2) to achieve voltage clamping. This allows the transient energy to be dissipated in the resistors and diodes,and limits the maximum voltage that may appear at the inputs.source

The tone generator (top) uses the 5589 chip and a DIP switch. You can actually hear the tones through the speaker. The bottom circuit uses the 8870 to decode a tone and display its associated number on the 7-segment LED. source

The above circuit uses a PIC18F452 to decoding Morse Code. The circuit is shown with a GLCD , the relevant point is the connection of the key/button to the PIC, it can easily be changed to any pin you like and the code should work on most PIC chips. Read the notes in the programs for more details.source