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Use relay to control extra fan on or off
#1
Use relay to control extra fan on or off
relay controled by Da vanci standard fan
relay connect to the extra fan(get porwer from USB)
when hotends over 50°C, two fans auto turn on
when hotends below 50°C, two fans auto turn off
it is convenient
All FW can use this method.[Image: IMAG2789.jpg][Image: IMAG2790.jpg]
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#2
This has been discussed on here a few times... I don't think you're getting the result you really want.

The OEM fan is controlled via PWM. The mechanical relay you're using can't switch fast enough for PWM. Who knows what kind of speed the AUX fan you added is running at...
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#3
Quote:This has been discussed on here a few times... I don't think you're getting the result you really want.

The OEM fan is controlled via PWM. The mechanical relay you're using can't switch fast enough for PWM. Who knows what kind of speed the AUX fan you added is running at...
Hi Tom
thanks for your reply
sorry~ I do not know what is PWM~~~
you mean that two fans will get slow??
I only take 3mA from OEM fan
it will get fans slow??
thanks for your reply~
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#4
PWM mean Pulse Width Modulation http://en.wikipedia.org/wiki/Pulse-width_modulation

It's a method of controlling analog devices like motors. The OEM fan isn't on/off like a switch... the speed varies, contolled by PWM.
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#5
Quote:PWM mean Pulse Width Modulation http://en.wikipedia.org/wiki/Pulse-width_modulation

It's a method of controlling analog devices like motors. The OEM fan isn't on/off like a switch... the speed varies, contolled by PWM.

Thanks~~~
now I know :cheer:
I know the OEM fan is not on/off , the speed varies(now i know it controled by "PWM"~~)
but when it is printing
the OEM fan is still running, the different jus fast or slow, it will not off. right???
if that is right~ the fan still got 5V to let fan running right?

let me show you how I connect
I use 5V 3mA to be a signal(from OEM fan)
to let the relay turn on
when printing. relay is on (because OEM fan is on)
the AUX fan get 5V 1A from PC's USB
the AUX fan is not controlled by PWM
only on/off
so I think my AUX fan is full speed~
maybe I am wrong. Sorry~~

so what is your suggestion?
thanks your reply~[Image: IMAG2792.jpg]
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#6
Your mechanical relay may still be switching on/off. It can be affected by PWM, but it's not fast enough to transfer PWM. You should be using a solid-state relay.
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#7
Quote:Your mechanical relay may still be switching on/off. It can be affected by PWM, but it's not fast enough to transfer PWM. You should be using a solid-state relay.

forgive me~
now I know what you mean~~
you mean my relay will switching on/off quickly
if my relay is switching on/off
it will "click~click~click~" right??
but I do not hear that sound~~
maybe I can take video to show you
I want to buy SSR. But it is rare and more expensive~~
thanks for your suggestion~
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#8
I just use "unload filament"
to show relay will turn on at 50 degree
and is not switching on/off
maybe tomorrow I will take video
that is printing something~
http://youtu.be/cnKDmhXbrZc
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#9
You don't need a big power-rated SSR, you can use a smaller transistor...
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#10
thanks for your suggestion
maybe when I see my relay clicking
I will try a transisotr.
transisor is a good idea.
but I want to use SSR to control 3M Air Purifier :cheer:
http://www.filtrete.com/wps/portal/3M/en...926&rt=rud

maybe Omron SSR is a good chiose?
http://www.aliexpress.com/item/1-Channel...87852.html
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