Noodle voltage

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Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Noodle voltage

Hi,

I just bought some noodles that are 3 volts. I see you sell a voltage regulator that jumps it down to 3.3 Volts. Would 3.3 V fry my noodle?

I’m going to be using a 9 V power supply on my project. And I just need to step the voltage down.

Do you have another solution for me that would bring the voltage down?

Thank you,
Shawn McClure

dastels

Posts: 16382
Joined: Tue Oct 20, 2015 3:22 pm

Re: Noodle voltage

You could add a 6 ohm resistor in series with the noodle to drop the "extra" 0.3v (and limit the current to 50mA as suggested). From the product page:
We recommend current limiting with a resistor to let max 50mA through, so think of them as a If=50mA, Vf=3V LED and calculate the resistor that way.
Those values get entered into the calculator at https://www.digikey.com/en/resources/co ... s-resistor.

Dave

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

Thank you Dave,

I think I might have found the thing from 9 volt to 3 volt.

https://www.mouser.com/ProductDetail/ST ... TgzQ%3D%3D Would that do the trick? I found this link on Google:
https://www.sparkfun.com/datasheets/Com ... 117V33.pdf

Shawn

Timeline

Posts: 414
Joined: Sun Feb 18, 2024 7:13 pm

Re: Noodle voltage

Since they act just like any LED, you can simply use a current limiting resistor. When run off of 3.3V, as Dave said, you would need (3.3-3.0)V/50mA = 8 ohms. If you are using 9V then it simply becomes (9-3)V/50mA = 120 ohms. However note the power dissipated by the resistor will be 6V x 0.05A = 0.3W so you have to use something higher rated than a basic "quarter-watt" resistor. If you were to buy a resistor then get 1/2 W ones.

If you already have a bunch of 1/4W resistors you can hook up more than one in parallel or series to dissipate that power over several of them. For example a pair of 240 ohm resistors in parallel or a pair of 60 ohm resistors in series. Either configuration brings you down to 0.15 watts dissipated in each resistor. Or to give you more margin, 3x 360 ohms in parallel and then it is only 0.1W per resistor, plus hooking them in parallel tend to be easier than stringing them in series.

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

Wow. I have a lot to learn about resistors. I’ll have to do my homework

Thank you for the help.

Thank you,
Shawn.

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

Well, I’ve tried to figure out what I need for this. Electronics just stump me honestly. I don’t understand electronics for some reason.

With that being said, can anyone send a link of a resistor that will pull the voltage down by .3 volts to go from 3.3 volts to 3 volts? I’ve tried attaching the resisters to my LD 33V reducer, but I still get 3.3 volts.

Shawn

Posts: 88562
Joined: Sat Feb 07, 2009 10:11 am

Re: Noodle voltage

With no load, the voltage drop across the resistor will be zero, so you will still see 3.3v.

https://en.wikipedia.org/wiki/Ohm%27s_law

If you wire a 6 ohm resistor in series with the noodle, you should see about a 0.3v drop across the resistor and about a 3v drop across the noodle. 6 ohms at 0.3v should limit the current to 50mA.

https://www.digikey.com/en/resources/co ... s-resistor

Timeline

Posts: 414
Joined: Sun Feb 18, 2024 7:13 pm

Re: Noodle voltage

Doesn't look like Adafruit carries any 6-ish ohm resistors so...
https://www.digikey.com/en/products/det ... -6R2/11921

When hooked up you should be able to measure...

3.3V --- 6.2ohm resistor --- (3.0V) --- Noodle --- GND (0V)

So at the junction between the resistor and noodle, that is where you will see 3V. The 3.3V supply stays at 3.3V.

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

Thank you so much. I really appreciate the help.

Shawn.

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

Well, unfortunately that didn’t work. The resistor didn’t bring the voltage down at all. I tried hooking two together and still didn’t do it.

Here are the pictures.

Any suggestions?

Thank you,
Shawn
IMG_5196.jpeg (311.23 KiB) Viewed 66 times
IMG_5199.jpeg (435.71 KiB) Viewed 66 times
IMG_5197.jpeg (371.27 KiB) Viewed 66 times

Timeline

Posts: 414
Joined: Sun Feb 18, 2024 7:13 pm

Re: Noodle voltage

You need to show your whole circuit. Looks like the pictures you are putting 9V into what is maybe a voltage regulator (ST Microelectronics?) and are measuring the output of that? If so then your regulator will always output 3.3V. To repeat what I said before...
3.3V --- 6.2ohm resistor --- (3.0V) --- Noodle --- GND (0V)

So at the junction between the resistor and noodle, that is where you will see 3V. The 3.3V supply stays at 3.3V.
To be clear the (3.0V) is not a supply or a component but me crudely indicating what you should be measuring at the resistor to Noodle junction. Looks like you are measuring the first element of my ASCII graphic, the 3.3V point? Did you have the noodle in series with the 6-ohm resistor? What you show that you are measuring doesn't look correct for a 78xx or LM317 type linear regulator.

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

OK. So the reason I didn’t put the noodle in there is because it’s only rated for 3 V. So I figured I would measure the voltage of the output and it still measured 3.3 V. So that’s fine.

So I figured, if it’s gonna blow up the noodle up. So I use the actual noodle, thinking it would short it fry it because of too much voltage. But just the opposite happened and it lit up just fantastically.

So I guess that’s it it worked. Sorry, I didn’t try hooking it directly up again, but I was just afraid it was going to fry it out.

Anyway, thank you very much for your help. I really do appreciate it.

Shawn.

Timeline

Posts: 414
Joined: Sun Feb 18, 2024 7:13 pm

Re: Noodle voltage

Out of curiosity, did you measure the voltage at the function of the resistor and the noodle with respect to ground? And was it close to 3.0V?

Shawnmcclure

Posts: 10
Joined: Mon May 06, 2024 7:43 pm

Re: Noodle voltage

Actually it’s 2.67 volts. The noodle is a little less bright than it is at a solid 3 V. I can adjust my power supply, so it just puts out the 3 V and it’s definitely brighter.

Would there be a better choice as far as Resistor goes to make it a little bit brighter?

If not, I can live with the way it is.

Thank you ,
Shawn

Timeline

Posts: 414
Joined: Sun Feb 18, 2024 7:13 pm

Re: Noodle voltage

Well your power supply is set for 9V, correct? And you have some sort of voltage regulator that turns 9V into 3.3 volts, correct? If both of those are yes, then adjusting your power supply output won't change the 3.3V since your regulator is going to work hard to keep the output at a steady 3.3V regardless if your supply is 9V, 8V or 10V.

Out of curiosity, with everything hooked up and working correctly, what is the current your supply is showing? Could it be your current limit knobs are turned way down? Easy way to check this is unhook the power supply from your circuit and simply short the the two wires together. The "C.C." (constant current) LED under and between the current knobs will come on and it should show you what the current is limited to. It it is less than 0.05 on the meter display, there is your problem. Adjust the knobs and put it over 0.05. Live it up and make it, say, 0.1. Now un-short them and hook it back up to your noodle circuit.