Hi All,
I am having a problem with switching circuitry using CMOS Logic. The simplified schematic I've attached shows what I am trying to do. I have 2 banks of relays (A,B,C, and D,E,F) and I want to cycle between them, but when one bank is selected, the other bank switches off.
I have built and tested the circuit and it works sort of, but I can't figure out the sort of part. Both banks work fine when they are selected, the problem lies with the unused bank. If say bank "A,B,C" is on, and E is the relay selected, then the 4017 outputs a 12V to it's gate, but D and F also see 5-7V (rising slowly too) when I expect 0V. All of these relays are then turned on.
I've tried strapping a high value resistor across the bank MOSFETs, thinking the floating 12V was a problem. I then added a second high value resistor across all of the relay MOSFETS, and I've tried removing pulldown resistors (not shown on the schematic) and nothing has worked. This is my first real foray into using Logic as switches so I'm completely stumped.
Anyone see anything or can point me to a solution? Thank you in advance!!
I am having a problem with switching circuitry using CMOS Logic. The simplified schematic I've attached shows what I am trying to do. I have 2 banks of relays (A,B,C, and D,E,F) and I want to cycle between them, but when one bank is selected, the other bank switches off.
I have built and tested the circuit and it works sort of, but I can't figure out the sort of part. Both banks work fine when they are selected, the problem lies with the unused bank. If say bank "A,B,C" is on, and E is the relay selected, then the 4017 outputs a 12V to it's gate, but D and F also see 5-7V (rising slowly too) when I expect 0V. All of these relays are then turned on.
I've tried strapping a high value resistor across the bank MOSFETs, thinking the floating 12V was a problem. I then added a second high value resistor across all of the relay MOSFETS, and I've tried removing pulldown resistors (not shown on the schematic) and nothing has worked. This is my first real foray into using Logic as switches so I'm completely stumped.
Anyone see anything or can point me to a solution? Thank you in advance!!
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