Voltage Divider

[axro]

Are the only time voltage dividers(potential dividers) any good is when the thing connected to Vout is going to have really high resistance?

Because if you have 2 equal resistors, you get VCC/2, then you add resistance to Vout the Voltage changes completely. So do you have to figure Vouts added resistance into the equation when designing your voltage divider or do you just stick to Vout with very high resistance?

 

[crutschow]

You can do either one. It's your preference.

 

[kjennejohn]

If the load represents a high load and effects the divider's output, then you introduce an isolation buffer (AKA instrumentation buffer) between them. This is typically an op amp with a FET input. This looks like millions of Ohms at the input, and just a few Ohms at the output. Goto Digikey.com and try searching on "isolation buffer". The link you get is
Linear - Amplifiers - Instrumentation, OP Amps, Buffer Amps | Digi-Key
At some point you will want to study buffers like this if you actually have to get past this problem.
Later.
kenjj

 

[3v0]

Mouser lists several Instrumentation Amplifiers at about $2. Is there any significant difference between isolation amps and Instrumentation amps.

EDIT
https://www.mouser.com/Semiconducto...umentation-Amplifiers/_/N-6j73w/?Ns=Pricing|0

 

[vlad777]

... thing connected to Vout is going to have really high resistance? ...

You want whatever is connected to out to have high resistance.
This way your pot behaves like voltage source with low internal resistance.