Very important in order for this to work correctly ONLY 1 switch PER row should be closed!
I was curious about this device so I decided to represent the circuit here.
In the actual device the switches are header pins and you only have 1 header cap for each row, avoiding the chance of closing multiple headers in each row. Due to the limited space only 3 groups are shown here. The actual device has the groups from ones to Mega ohms, allowing 1 ohm to 9,999,999 ohm resistor values.
What I dislike with the design is the high possibility of a short circuit (when all NULL switches are closed. For this sim placed the 1uohm resistor which is not present in actual device.)
Source: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F371144195602
MSian 04/2019
