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Old 09-14-2018, 01:25 PM   #8
momaka
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Default Re: Modifying laptop adapter for 12v

Quote:
Originally Posted by Dannyx View Post
By "lower resistor" you're referring to the one going to GND ?
Correct.

Quote:
Originally Posted by Dannyx View Post
I was concerned that lowering the resistance between that pin and GND will cause more current draw, so I thought I'd lower the VCC one instead
You misread my above post.

If changing resistor between pin 2 and ground, _increase_ the resistance. (This will cause a higher voltage readout at pin 2, and hence more often pulling of the output to ground).

If changing resistor between pin 2 and Vcc, _decrease_ the resistance. (This will cause a higher voltage readout at pin 2, and hence more often pulling of the output to ground).

Quote:
Originally Posted by Dannyx View Post
CORRECTION: with the inverting input tied directly to GND...
Well, if you are trying to have any kind of regulation, you never tie any of the op-amp pins to ground.
And if you tie pin 2 to Vcc, your PSU will output the reference voltage set by the resistors on the lower-right side of your diagram (the ones that connect Vcc, pin 5, and ground).

Last edited by momaka; 09-14-2018 at 01:31 PM..
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