Author Topic: Adding LED (or?) to shield fan help  (Read 3871 times)

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Offline Bashy

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Adding LED (or?) to shield fan help
« on: June 23, 2017, 01:01:15 AM »
Hi Folks

Due to me temp shield being 13ft up the mast, it has become impossible to know if the fan is still running
Its a 12v fan running 24/7, its no good just running the LED at the end of the cable cause that does not tell
me if the fan is actually spinning/drawing power. Any thoughts please?
Kind regards
Bashy

Offline DanS

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Re: Adding LED (or?) to shield fan help
« Reply #1 on: June 23, 2017, 02:21:05 AM »
You could take current readings for the fan when it's running correctly and note the reading. Then from time to time take readings to confirm they're the same because if/when the fan stalls or is blocked from turning then the current reading increases slightly.
An example, I have a 12v computer fan (brushless) with a 160mAh rating. When I connect it to a power supply set to 12v I see about 160mAh current draw. When I stop the fan from turning I get over 200mAh current draw.
If your are powering other things on the same leads, such as the temp/humidity sensor, of course the current readings will be higher. The fact is the increase over the normal is what to watch for. YMMV. ;)
« Last Edit: June 23, 2017, 02:34:20 AM by DanS »

Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #2 on: June 23, 2017, 02:35:07 AM »
Hi, thanks, Im not so sure it would work as its on a PC PSU and other items are running on it too
but not only that, its not easily accessible due to junk in the shed (dont go there lol)

I was hoping adding a LED with perhaps a resistor or capacitor (cant ya tell i dont know what im talking about)
inline and the LED added between that and the fan, not possible? i do not know electrics

I was just hoping there would be a way so i can see at a glance if its still running or not
Kind regards
Bashy

Offline DanS

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Re: Adding LED (or?) to shield fan help
« Reply #3 on: June 23, 2017, 02:56:24 AM »
Unfortunately an LED would just stay lit regardless of the fan's state (even if it could handle to load of all the electronics inline).

Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #4 on: June 23, 2017, 03:04:41 AM »
Damn, such a shame, i spose i should have glue a fine ribbon to it, least i would know on a calm day lol

Just seen [url-https://www.weather-watch.com/smf/index.php/topic,65083.0.html]this[/url] it is an idea
but would take too long to implement, mast would be down too long :/

I spose a digital V meter would suffice, i could stick it in the shed window....

Thanks for your advice :)

PS or would it need to be an amp meter?
Kind regards
Bashy

Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #5 on: June 23, 2017, 03:18:52 AM »
This might be over kill but there is an alarm function :D
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Bashy

Offline WeatherHost

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Re: Adding LED (or?) to shield fan help
« Reply #6 on: June 23, 2017, 03:21:56 AM »
Have you considered the various lighted computer fans?  They come in all sorts of colors now.  They may stay lit if the fan is obstructed, but you still may be able to tell if the blades aren't spinning.  Maybe with binoculars or a camera telephoto lens.  LEDs are off if there is no power for some reason.
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Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #7 on: June 23, 2017, 03:30:41 AM »
Sadly, not possible to see the fan in a Davis shield
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Bashy

Offline DanS

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Re: Adding LED (or?) to shield fan help
« Reply #8 on: June 23, 2017, 03:37:25 AM »
I was thinking along WeatherHost's PC fan replacement idea and was wondering if you could swap the fan for a PC fan. You could use the multi-lead type with tach out and run that lead down where you could get to it. Several options to use that tach-out lead to see if you're running or not.

Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #9 on: June 23, 2017, 03:41:55 AM »
I think it is pc fan but I think only a 2 wire
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Bashy

Offline WeatherHost

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Re: Adding LED (or?) to shield fan help
« Reply #10 on: June 23, 2017, 04:31:04 AM »
Sadly, not possible to see the fan in a Davis shield

You're the one who brought up the idea of an LED, so if you can't see it, what were you hoping that would accomplish?

Other ideas might be a small camera, or maybe a microphone to 'hear' if the fan is running, but now you say you only have two wires --  so maybe you have to run more.

Then again, if it's only 13', maybe a ladder would do as well as anything else.




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Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #11 on: June 23, 2017, 04:34:38 AM »
It would have been mounted below the shield...

I dont know of any ladders that would stay put when lent against a mast, would be on my ass before i knew it :)
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Bashy

Offline WeatherHost

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Re: Adding LED (or?) to shield fan help
« Reply #12 on: June 23, 2017, 06:27:34 AM »
Below the shield to do what?  How would it determine if the fan was running or not?  It might who that power was available, but not that the fan is/was obstructed.  Even if it was in series after the fan motor.  The metering mentioned might show increased load/power consumption, but that still wouldn't show if the fan was running or if there was some other problem.

A camera would be the only thing to do that.

A person standing on a 12' step ladder would get to the 13' level to view.  They're not inexpensive though.

 
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Offline WeatherHost

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Re: Adding LED (or?) to shield fan help
« Reply #13 on: June 23, 2017, 06:30:43 AM »
For that matter, you could use a small video camera mounted to an 8' stick (1x2).  Start the video camera recording, raise the stick into place to see whatever it is you want to see, then lower it and view the recording.  Some of them have sound, so you could listen to the audio of the fan running.
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Offline vreihen

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Re: Adding LED (or?) to shield fan help
« Reply #14 on: June 23, 2017, 06:34:34 AM »
I would be curious if someone has a 3-wire computer fan available to see if an LED connected between the tach wire and ground will vary in brightness based on fan speed:

http://www.petervis.com/electronics%20guides/cpu%20fan%20tacho/cpu%20fan%20tacho.html

https://electronics.stackexchange.com/questions/8295/how-to-interpret-the-output-of-a-3-pin-computer-fan-speed-sensor

Remember that LEDs have polarity, so reverse the legs if it doesn't light the first time.

On second thought, pick up an aftermarket automotive/small engine electronic tachometer and hook the signal wire up to the fan's tach output:

https://www.youtube.com/watch?v=57QN1WyMd6E

https://www.amazon.com/NCElec-Universal-Backlit-Tachometer-Gasoline/dp/B01M6D0IRJ

https://www.amazon.com/Docooler-Digital-Tachometer-0-9999RPM-Warning/dp/B00FDNGDSM

The links above say that a typical PC fan sends two pulses per rotation, so a tach set for 4 cylinders on a 4-stroke engine would actually even read the correct fan RPM if my math is correct.....
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Offline Phil23

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Re: Adding LED (or?) to shield fan help
« Reply #15 on: June 23, 2017, 07:14:14 AM »
How about a photo interrupter type of setup.

A transmitter led below the fan & receiver above it.
The blades would break the beam.

Then a simple counter /divider chip to pulse a LED.
It would only blink when the blades were breaking the beam to generate the input pulses.

Others here will understand what I mean & might be better able to suggest a simple circuit.

Offline DanS

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Re: Adding LED (or?) to shield fan help
« Reply #16 on: June 23, 2017, 07:21:11 AM »
" I would be curious if someone has a 3-wire computer fan available to see if an LED connected between the tach wire and ground will vary in brightness based on fan speed:"


Funny you would mention that because I just tried that very thing. I tried it with a pull-up resistor to 12v then a pull down to gnd (flipping the LED around). The LED just stayed lit even with the fan stopped with my finger, power still applied. I was going to suggest an LED and resistor to monitor the Tach Out line but after that test I guess not.  #-o
« Last Edit: June 23, 2017, 07:43:30 AM by DanS »

Offline dupreezd

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Re: Adding LED (or?) to shield fan help
« Reply #17 on: June 23, 2017, 07:43:16 AM »
I have done it recently when I build my shield for a Ambient WS-1200. I used a 3 wire fan. The tach output is connected to a led, a 1.5k resistor to +12V. The tach is an open collector output with a 50% duty and  varies according to speed.
I made the mistake to use a green Led so I can only see the it at night.
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Offline DanS

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Re: Adding LED (or?) to shield fan help
« Reply #18 on: June 23, 2017, 07:50:04 AM »
I must have a bad fan then if yours works that way. Is it possible to have a 3-wire fan and the yellow wire is a throttle input (pulled high)? If so maybe thats what I'm dealing with.

Offline dupreezd

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Re: Adding LED (or?) to shield fan help
« Reply #19 on: June 23, 2017, 07:57:29 AM »
The cathode of the LED goes to the Tach. Oh, and check your resistor. I used a 15K by mistake the first time. The orange band was almost red.

The  4 wire fan (normally blue wire) have PWM input which is the speed controller.
« Last Edit: June 23, 2017, 08:01:03 AM by dupreezd »
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Offline DanS

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Re: Adding LED (or?) to shield fan help
« Reply #20 on: June 23, 2017, 08:04:31 AM »
Understand LED polarity identification with the cathode going to the tach-out. I tried it that way so the onboard transistor (open collector) would pull the LED to ground and light it (with a pull up on the anode to 12v), but, with the fan stopped (power still applied) I still had a lit LED which made me scratch my head.
I have some other 3 and 4 wire fans to play with now that my curiosity is stirred up.
 
« Last Edit: June 23, 2017, 08:10:34 AM by DanS »

Offline dupreezd

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Re: Adding LED (or?) to shield fan help
« Reply #21 on: June 23, 2017, 08:13:00 AM »
Yep, looks like the internal tach transistor is shot. Do you have another 3 wire fan laying around to play with? They are commonly used in computers. Even a 4 wire will work, just leave the PWM disconnected.

BTW. if you connect the PWM input between the LED and resister, the fan runs half speed.  :grin: It use it own tach output, 50% duty, to set the half speed.
« Last Edit: June 23, 2017, 08:34:49 AM by dupreezd »
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Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #22 on: June 23, 2017, 09:08:07 AM »
Below the shield to do what?  How would it determine if the fan was running or not?  It might who that power was available, but not that the fan is/was obstructed.  Even if it was in series after the fan motor.  The metering mentioned might show increased load/power consumption, but that still wouldn't show if the fan was running or if there was some other problem.

You see, that was why i asked on here, if i knew how to do it i wouldnt be asking ;) The LED would be sited underneath the shield.

Now looking at the following posts, it is possible so my idea was not that lame really was it?
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Bashy

Offline Bashy

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Re: Adding LED (or?) to shield fan help
« Reply #23 on: June 23, 2017, 09:09:39 AM »
The cathode of the LED goes to the Tach. Oh, and check your resistor. I used a 15K by mistake the first time. The orange band was almost red.

The  4 wire fan (normally blue wire) have PWM input which is the speed controller.


I will have to order a fan in, i have two new ones but i am sure they are 2 pin, will check
and then i need to get some resistors, and look up cathode lol, thanks, i thought they may have
been a way to do it :)
Kind regards
Bashy

Offline W9LRT

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Re: Adding LED (or?) to shield fan help
« Reply #24 on: June 23, 2017, 09:10:42 AM »
I haven't done it for this application, but a three/four terminal fan with the tach output connected to a missing pulse detector (built with a 555 timer, circuits all over the internet) could be setup to actually light an LED when the fan is not running.  Get creative with a multi-color LED and it could be one color running and another when stopped.

Example circuit: http://electronicsarea.com/missing-pulse-detector-circuit-555-timer/