I have a hypothetical I am trying to work out, initially I was thinking something like a make before break circuit.
I have a need to design a circuit of which these parameters are necessary:
The circuit is below 24V, probably going to be 12v for final design
I have four devices of which the load on them needs to be absolutely constant to maintain their ideal operation, and data will be garbage if not held.
I have an extremely out of my budget measurement device, that can only measure one device at a time, and also needs the current coming from the devices to be mostly constant.

The load I will be matching is the resistive load of the measurement device, so the 4 devices would be kept at a load matching this when not measured

Instead of buying three more of these measurement devices, it is obviously possible to use MOSFETS as a relay to switch between them, but what I don't know is if it is possible to switch them without a noticeable impact on the loading of the devices.

These devices would be hooked up to a load when not on the measuring device, and transitioned to the measurement device.
Is there a circuit that exists, similar to a make before break circuit, or dissimilar, that would allow for a seamless transition of resistive loading on devices?

 

What parameter are you trying to measure?

 

What parameter are you trying to measure?

current and voltage output of the devices, and this is all being done in a lab, so the measurement tool is fairly refined, and I would prefer to just interface with it if possible.

 

What is the measuring device?

 

What is the measuring device?

It was custom made for the lab, the functions I am using it for are just measuring output current and voltage. The measuring device itself is not relevant to my question at this time. I'm asking about seamless load switching. It just has a positive and negative probe connection for this.

 

Does the measurement device provide the load? If not, do you need to switch the load? Presumably it measure voltage with two probes and current with a shunt resistor. Can you just switch the connections to the probes?

 

Does the measurement device provide the load? If not, do you need to switch the load? Presumably it measure voltage with two probes and current with a shunt resistor. Can you just switch the connections to the probes?

Yes, so the measurement device provides the load as the load impacts the output of the devices. The devices become unstable when the load is varied, and they operate very unstably when switched on and off a load, such that the devices fail after one round of testing anyway. This is why the load must be kept constant unfortunately.

 

Get rid of the unstable power supplies - it is something you just don't need in your life. It would be poor engineering practice to design in a component that it knowingly unstable and unreliable. The ability of power supplies to cope with load transients has been understood for decades. Why are you using such a poor component?

 

and what are you measuring? is it AC or DC? post some numbers... (voltage, current...).