20-05-2025, 10:28 AM
I have been busy with a lot of other things lately, not all desirable, but I have finally got a working frequency / wavelength display unit, as mentioned in my last post. I have used an Arduino Uno along with the input amplifier, mentioned above, and a 74LS74 double flip flop chip to provide a divide by four function. This enables the unit's range to extend well beyond 10MHz which is all I intend at the moment. It is fairly easy to change a module if required though.
For the programming I used software which is available online via this link: https://www.gammon.com.au/timers . All I have done is add functionality for calculation and modification of frequency data and for the LCD display. As such I won't show my code as other implementations will require similar, but possibly different, adaptation.
The photos shown give output using a precision input source (crystal oscillator with oven) although it's not been calibrated except as it was supplied (Chinese via Ebay). They show results plus internal layout.
1: The unit with an early version of the program which shows frequency input in Hz and the correct frequency (I/P x 4). I do notice and error of 3Hz but this may be rounding (check needed but not too much of an issue).
2: This shows the display using version two of the program which rounds output to KHz. Wavelength is calculated not using the usual approximation (300) and may be rounded lower or be more correct but needs checking. I do feel that wavelength is probably only required with radio tuning though so the displayed information may well be changed. Early days yet!
3: The display when there is no input. When the oscillator frequency is too low to be sensible for radio the frequency is still shown but all others show N/A. I may change the display deleting the oscillator wavelength and show oscillator frequency in HZ as well as kHz such that lower frequencies below 1KHz can be displayed. For normal radio tuning though 1kHz steps are gentler.
4: The internal layout.
For the programming I used software which is available online via this link: https://www.gammon.com.au/timers . All I have done is add functionality for calculation and modification of frequency data and for the LCD display. As such I won't show my code as other implementations will require similar, but possibly different, adaptation.
The photos shown give output using a precision input source (crystal oscillator with oven) although it's not been calibrated except as it was supplied (Chinese via Ebay). They show results plus internal layout.
1: The unit with an early version of the program which shows frequency input in Hz and the correct frequency (I/P x 4). I do notice and error of 3Hz but this may be rounding (check needed but not too much of an issue).
2: This shows the display using version two of the program which rounds output to KHz. Wavelength is calculated not using the usual approximation (300) and may be rounded lower or be more correct but needs checking. I do feel that wavelength is probably only required with radio tuning though so the displayed information may well be changed. Early days yet!
3: The display when there is no input. When the oscillator frequency is too low to be sensible for radio the frequency is still shown but all others show N/A. I may change the display deleting the oscillator wavelength and show oscillator frequency in HZ as well as kHz such that lower frequencies below 1KHz can be displayed. For normal radio tuning though 1kHz steps are gentler.
4: The internal layout.
