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What happens when I add this resistor?

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Sparky_s

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I have a wall transformer and the output is 24 VDC 500 mA.
I want to add a 3.3 K-Ohms resistor in serie.

What would be the output? It would decrease the voltage or the voltage and the current?
thanks
 
Depends on the load? If you hang a 3.3 K resistor out there and measure with a meter having a 10 M Ohm input you will measure pretty much 24 VDC. The voltage drop across the resistor will be a function of the current the load draws. You aren't providing enough information for anyone to answer.

Ron
 
If you want to have an output that's different than 24V, you'll need a resistive divider, which requires two resistors.
 
To explain me better, I've seen this:
https://pulsar.li/en/images/batterieset02.jpg

The device is used to make water with mineral colloids. When you put 2 electrodes under water, then you can make some colloidal suspension (the electrodes dissolve and release the metal into the water).

My doubt is what function has the resistor there.
 
It limits the current. Electrolysis and plating generally use constant current sources rather than constant voltage sources. Pure water doesn't conductelectricity well, but add some impurities and everything changes rapidly.
 
Silver colloids are a poison that turns your skin into a bluish-grey color. It is not a medicine. Look at it in Google. (But don't look at the ads that sell the junk).

The 3.3k resistor limits the current to about only 8mA in case the 27V from the batteries is shorted. Shorted batteries get very hot if the current is not limited.
 
To explain me better, I've seen this:
https://pulsar.li/en/images/batterieset02.jpg

The device is used to make water with mineral colloids. When you put 2 electrodes under water, then you can make some colloidal suspension (the electrodes dissolve and release the metal into the water).

My doubt is what function has the resistor there.

OK now you have a load out there. You have 3 x 9 volts = 27 volts and as mentioned the 3.3 K resistor is there to limit the current. The load being what the probes go into and as mentioned all water conducts differently depending on the impurities. Give it a shot and see what happens. You can't calculate the current without actually knowing the conductivity of the water but a nice little experiment. Heck, go for it! :)

And per AG be careful!

Ron
 
Last edited:
Thanks to all for the answers.

To AG,
It's not for human, it's to make an observation with plants. Thanks for the advice.
 
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