By Earl Backed up here From Rwg
I have not been able to find what frequencies Stanley was using as input to the VIC so decide to analyze the circuit diagram for the Main Frequency Generator Board. It's a simple circuit but my electrical engineering skill are very rusty and finding the data sheets and an use article with what information I needed was not very straight forward. But I think I have figured it out. I wrote the attached document to describe how I think it works. Short answer is 4 frequencies are generated on this board. Left to right from the 555 through each of the 7490 chips the frequency get divided by 4. So highest is on left lowest on right which matches up to numbering on switches. Assuming the center range of the pot is being used the 4 frequencies are: 1.2KHz, 300Hz, 75Hz and 18.75Hz. The Pot on the 555 is only adjustment in systems. But there are loops on board for O-scope probe to see output of each step. The attached document shows all the inputs and outputs and what I think is being done by each element and why. It maybe over kill but it just the way I think and what I wanted to know. The 7490 was the hardest as most of the data sheets talk about it being a counter but in this case it is being used as a divider (still counting but results is division) there is a link to article that explains why in the document. Most likely easier way to do this but a least now I know what Stan was using.