Author Topic: 5V fan behind Jack DC  (Read 884 times)

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Offline Kantilo

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5V fan behind Jack DC
« on: May 22, 2021, 11:11:41 pm »
Hello, I got a guide that uses a 12V fan in a project, and I would have liked to adapt it to a 5V fan, can you confirm that my way of doing things is ok?
Project instructions for the 12V :
Quote
Wiring Instructions:
1 Connect the fan power pin to one of the switch terminals
2 Connect the other switch terminal to the DC jack positive terminal
3 Connect the fan ground pin to the DC jack ground terminal

So I was going to take a female DC Jack, and a fan extension that I cut in half to recover male and female, I cut the fan connector and connect the fan to the extension on the male side, a schema :


On the DC Jack connector there is a long and short pin, the short pin = the pin inside?
Should be ok, right?
Thanks
 
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Re: 5V fan behind Jack DC
« Reply #1 on: May 22, 2021, 11:55:28 pm »
Well, a DC jack has connectors for the center pin and the barrel. Which is positive versus negative depends entirely on the DC adapter you plug into it.

Most DC adapters are center positive, but this is not universal. Check the polarity symbol on the adapter itself, e.g.:

[attachimg=1]

As for the connections on the DC jack... I would verify all of your assumptions with a multimeter. Usually the tab towards the rear of the jack is connected to the center pin, but you should double check this for your jack.
 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #2 on: May 23, 2021, 01:48:56 am »
Thank you for your help, so a continuity test for the female jack, I touch the pin inside and one of the two pins, on the other hand for the USB adapter I will try to find but I believe that in voltmeter mode when I have the positive value that will mean that I have found the right polarity, if not on the whole it is coherent?
 

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Re: 5V fan behind Jack DC
« Reply #3 on: May 23, 2021, 02:20:48 am »
What USB adapter are you talking about? I don't see that mentioned in your original post.

 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #4 on: May 23, 2021, 02:34:39 am »
Something like this connected on my 5V adapter (old phone charger or another source)

 

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Re: 5V fan behind Jack DC
« Reply #5 on: May 23, 2021, 02:43:29 am »
Yeah, in this case plugging the cable into an active USB socket and measuring the voltage between the center and barrel is a good way to check the polarity.

Be careful not to short the leads while making the measurement. USB port are supposed to be short-circuited protected, but still it's not a good idea to short it out.

 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #6 on: May 23, 2021, 03:14:26 am »
Thank you for taking the time to help me, it is not good for the power supply I imagine, and not the multimeter, precisely I had a cut while using my soldering iron in USB PD when the tin was touching the tip (it doesn't do it all the time and it didn't do it for me again) do you have any idea where it could come from? Hope it didn't damage the soldering iron
 

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Re: 5V fan behind Jack DC
« Reply #7 on: May 23, 2021, 03:28:44 am »
Here's what I understand - perhaps you can clarify...

1. you have a soldering iron powered by a USB 3.0 Power Delivery adapter
2. while you were using it the tip of the soldering iron touched (something)
3. that created a short

Were you soldering on a powered circuit?

Is there some device that's not working now?
 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #8 on: May 23, 2021, 04:06:34 am »
That's exactly it, I have a video to illustrate the words, sorry I'm not English
https://files.catbox.moe/c1adnq.mp4

So it's not a powered circuit
So far nothing has been damaged but I'm afraid it will damage my soldering iron, I don't know if this is the case
« Last Edit: May 23, 2021, 04:09:32 am by Kantilo »
 

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Re: 5V fan behind Jack DC
« Reply #9 on: May 23, 2021, 04:24:35 am »
In the video what is the wire connected to?
 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #10 on: May 23, 2021, 04:27:00 am »
It's a coil of tin that I hold in my hand
 

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Re: 5V fan behind Jack DC
« Reply #11 on: May 23, 2021, 05:50:01 am »
Try a different power supply. I would try a transformer based wallwart. The Pinecil has a DC jack you can use for power.

The problem could be:

- the USB PD power supply
- the control electronics in the Pinecil
- the temperature sensor in the tip

Do you have another tip you can test with?
 
 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #12 on: May 23, 2021, 05:52:31 am »
I have a second pinecil I have exactly the same problem with it, and on both using the DC Jack port I don't have the problem
 

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Re: 5V fan behind Jack DC
« Reply #13 on: May 23, 2021, 06:26:13 am »
That suggests that the USB PD power supply is the problem.

Or, it could be the USB-C port on the Pinecil.

I'd try testing with another USB PD adapter.

I'd also try testing the USB PD adapter itself with other devices -- especially ones that can put the PD adapter into the higher voltages -- 15V and 20V.
 

Online BeBuLamar

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Re: 5V fan behind Jack DC
« Reply #14 on: May 23, 2021, 01:47:49 pm »
If you connect it with the wrong polarity the fan would run backward. No harm done.
 

Offline janoc

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Re: 5V fan behind Jack DC
« Reply #15 on: May 23, 2021, 02:03:30 pm »
If you connect it with the wrong polarity the fan would run backward. No harm done.

Uuuh, LOL, no  :palm:. Fans like these use BLDC motors driven by a piece of electronics in the hub. If you connect it in reverse, you will most likely destroy it, it will certainly not run backwards!
« Last Edit: May 23, 2021, 02:05:09 pm by janoc »
 
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Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #16 on: May 24, 2021, 03:00:35 pm »
Thanks for your help, since my post I haven't had any problems, do you think keeping the power supply will damage my soldering iron? I did a voltmeter test there is 20 Volt output

 

Offline janoc

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Re: 5V fan behind Jack DC
« Reply #17 on: May 24, 2021, 03:08:36 pm »
Pinecil specs:

Quote
USB type C: PD and QC 3.0 12V-20V 3A

On barrel jack it is meant to work with up to 24V.

So no, it won't damage it, at least as far as voltage is concerned.
 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #18 on: May 24, 2021, 03:17:46 pm »
The voltage is good, they changed the specs now the recommended maximum is 21V, however compared to the cuts I do not know where it came from in the long term I'm afraid that it will damage the soldering iron but it is expensive
 

Offline janoc

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Re: 5V fan behind Jack DC
« Reply #19 on: May 25, 2021, 05:14:26 pm »
The voltage is good, they changed the specs now the recommended maximum is 21V, however compared to the cuts I do not know where it came from in the long term I'm afraid that it will damage the soldering iron but it is expensive

Does not matter. If you are using USB PD supply, the device will negotiate only as much voltage as it can handle/needs. So unless your Pinecil is broken/buggy and asks for more than it can handle or your USB supply is not standard compliant you don't need to worry about it.
 

Offline Kantilo

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Re: 5V fan behind Jack DC
« Reply #20 on: June 21, 2021, 10:12:00 pm »
Thanks, and what about the cuts they damage the soldering iron?
 

Offline janoc

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Re: 5V fan behind Jack DC
« Reply #21 on: June 22, 2021, 11:09:44 am »
Thanks, and what about the cuts they damage the soldering iron?

You mean the power was interrupted? It will most likely not damage it but that is not normal either. You will want to fix that. Either the power supply is not sufficient for the current draw of the iron or there is some dodgy contact somewhere.
 

Online tooki

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Re: 5V fan behind Jack DC
« Reply #22 on: June 22, 2021, 04:00:37 pm »
If you connect it with the wrong polarity the fan would run backward. No harm done.
Absolutely, positively not true.

Quoted for emphasis:
If you connect it with the wrong polarity the fan would run backward. No harm done.

Uuuh, LOL, no  :palm:. Fans like these use BLDC motors driven by a piece of electronics in the hub. If you connect it in reverse, you will most likely destroy it, it will certainly not run backwards!
 


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