Hello, all,

I am trying to design a circuit where i want to switch between one resistor network to another. Could you advice me the type of switch i should be using also how will i be able to switch the circuit electronically using a switch.
I need to switch points A and B to points C and D as shown in the below diagram. But i do not know how i can do this and the type of switch to use. Please Help

 

This should work.
You could use a logic level MOSFET and one of your data lines to operate the relay.

 

What are the resistance values of the two resistors?

 

This should work.
You could use a logic level MOSFET and one of your data lines to operate the relay.

View attachment 159765

Thank you very much, I was thinking of a DPDT way to double pole both A and B lines. But its great that it works with SPDT. I dont know why i couldnt see it before. why am i such an idiot...

Also can you explain or source me to logic level mosfet? I was thinking of using an SPI type SPDT switch to perform the above mechanism.

 

What are the resistance values of the two resistors?

I would say 348ohm and 348.1Ohm. I need to simulate a trigger for a 350Ohm strain 3-wire quarter bridge

 

I would say 348ohm and 348.1Ohm. I need to simulate a trigger for a 350Ohm strain 3-wire quarter bridge

A differential of only 0.1 ohms is way too small to be accurately switched using a simple mechanical relay. The relay contacts themselves might have a resistance repeatability higher than that. I'd consider an alternative technique to accomplish what you want.

 

A differential of only 0.1 ohms is way too small to be accurately switched using a simple mechanical relay. The relay contacts themselves might have a resistance repeatability higher than that. I'd consider an alternative technique to accomplish what you want.

Would i be able to use the following switch along with standard resistors for this process?

https://www.maximintegrated.com/en/products/analog/analog-switches-multiplexers/MAX14763.html

 

Would i be able to use the following switch along with standard resistors for this process?

https://www.maximintegrated.com/en/products/analog/analog-switches-multiplexers/MAX14763.html

I don't know. The datasheet states that:

The MAX14759 features 1Ω (max) on-resistance with a ±200nA (max) on-leakage current. The MAX14761/MAX14763 feature 2Ω (max) on-resistance with a ±100nA (max) on-leakage current.

Again, the key issue here is repeatabitily, it doesn't matter if the switch that you use has a 2 ohm on-resistance, as long as it is always 2 ohms, and not 2.1 or 1.9 ohms, regardless of usage, temperature, and other factors. In all honesty, I don't think those chips can deliver what you want. But that's only my opinion.

 

I would say 348ohm and 348.1Ohm. I need to simulate a trigger for a 350Ohm strain 3-wire quarter bridge

Instead of switching between a 348.0 Ω resistor and a 348.1 Ω resistor, just leave a 348.1 Ω resistor permanently connected in the circuit and switch a 1.2 MΩ in parallel with it to bring the combined resistance down to 348Ω when the switch is activated. Just about any analog switch or relay should be able to do that, without worrying about contact resistance or ON resistance.