| Circuit Diagram | How to set the DIP switch | Bill of Materials |
Any carrier is essential for home-made ham radios. A generation ago, manufacturer-made equipment used PLLs to generate many different carriers, but recently, a convenient device called DDS has been developed, which is very useful when making your own transmitter/receiver. However, the internal structure of this DDS is very complicated, and you can generate the desired carrier by setting many register values. In reality, manufacturer-made equipment uses a CPU (microcomputer) to write commands to the DDS. For home-made radios, it is easy for station managers who can use the CPU, but it is a pain for station managers who are not good with CPUs. Therefore, I have created a simple DDS that does not use a CPU at all, and can generate any desired carrier just by turning on the power supply, so I would like to introduce it. |
| ① | The reference
clock frequency can be from 5MHz to 30MHz. When inputting the reference
clock from an external source, input 1.5Vpp or more to J1, short JP2, and
remove the built-in oscillator. When using the built-in oscillator, open
JP2 and insert the desired oscillator into the socket. |
| ② | For pulse output, JP1 is shorted, output is from J2, and a sine wave is output from J3. The minimum resolution of the output frequency is 0.1Hz. |
| ③ | Any frequency can be output by setting the DIP-SW (SW1 to SW4). When setting the DIP-SW, all SW settings are determined by inputting the reference clock frequency (green cell) and the desired frequency (yellow cell). Enter all values in Hz. |
| Output when reference clock = 27MHz and output frequency = 10MHz |
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