I have constructed a circuit as below to convert the input of 12 to
24V as 0 to 12V and show the voltage on a DC volt-meter. The schematics is shown below:VCC +24V + | .-. | | +24V 2k2| | VCC '-' + | | | 10K |\\| | +12V-|___|-+--|-\\LM358 | ___ | | >---+-----+ IN +-|___|---+-----|+/ | | | 10K | | |/| | | | | | === | | .-. | | GND | | | | | | ___ | | 2k2| | .-. +--|___|--+ /+\\ '-' | | 10K ( ) | 10K| | VOLT \\-/ | '-' | === | | GND | === === GND GND
(created by AACircuit v1.28.6 beta 04/19/05
I have the +12V reference taken from a TL431.
When the input voltage at "IN" is +12V I was not able to get a 0V on the voltmeter. Instead I am getting 0.58V at the output. Does this has something to do with the CMRR of the chip? How would I solve this problem? Would changing the op-amp to LM748 and connecting a pot between the balance inputs of the LM748 help to reduce the voltage to O?
Thanks In Advance!
Allen