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connect LED to hotend

Posted by Weedz 
connect LED to hotend
August 15, 2012 10:15AM
Small question

Is it possible to hook up a LED to the hotend power resistor. That way i could see if its on or off.
the hotend power risistor is on or off powered right....
Re: connect LED to hotend
August 15, 2012 10:30AM
This is how it is done on the old Gen3 Extruder Controller board:



Bob Morrison
W├Ârth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: connect LED to hotend
August 15, 2012 10:36AM
exactly just putting a 1k resistor and a LEd in parallel to the heaterresistor
Re: connect LED to hotend
August 15, 2012 12:00PM
The heater is PWMed, not just on off, so the LED will vary in brightness as well.


[www.hydraraptor.blogspot.com]
Re: connect LED to hotend
August 15, 2012 01:57PM
I assume this can be implemented on any current electronics board?


--

Charles S.
Software Engineer
Prusa Mendel I2, RAMPS 1.4, Marlin 1.0 R2, Pronterface, Slic3r
Re: connect LED to hotend
August 15, 2012 02:30PM
Yes, just make sure the LED is the right way round.


[www.hydraraptor.blogspot.com]
Re: connect LED to hotend
August 15, 2012 04:15PM

Re: connect LED to hotend
August 15, 2012 04:30PM
What sort of bed is the other MOSFET driving? In general you need to use all four pins and even then the connector may burn out.


[www.hydraraptor.blogspot.com]
Re: connect LED to hotend
August 15, 2012 04:31PM
Wouldn't that only have effect if you turn on a "second" extruder in your firmware?
Also, are there any specifications for the LED or does it not matter?

glyn Wrote:
-------------------------------------------------------
>

Edited 2 time(s). Last edit at 08/15/2012 04:33PM by Lodorenos.


--

Charles S.
Software Engineer
Prusa Mendel I2, RAMPS 1.4, Marlin 1.0 R2, Pronterface, Slic3r
Re: connect LED to hotend
August 16, 2012 03:24AM
ah ok so it is PWM i assumed it was on of just like my heatbed.
If i put a 1k resistor infront of the LED would it then be bright enough?. if i calculate the resistor needs it would be around 420Ohms if a assume that the LED takes 1.5V and 25 mA
Re: connect LED to hotend
August 16, 2012 03:51AM
10mA is plenty of current to be able to see it and will work with any small LED. 25mA pushes it close to absolute max for some LEDs.


[www.hydraraptor.blogspot.com]
Re: connect LED to hotend
August 16, 2012 04:25AM
ok and same would count for heatbed right. I have a MK2 heatbed but i have no room for the LED on the board itself. I have the heatbed connected to a realycircuit and i thinking of powering it from that.

i think i had some LED laying around with 35mA max but il go for 1k Res just to be on the safe side, if it will glow enough for noticing
Re: connect LED to hotend
August 16, 2012 09:17AM
Quote
Lodorenos
Wouldn't that only have effect if you turn on a "second" extruder in your firmware?
Also, are there any specifications for the LED or does it not matter?

That is the main power to the extruder heater... works for me.
Re: connect LED to hotend
August 29, 2012 07:40AM
glyn Wrote:
-------------------------------------------------------
> That is the main power to the extruder heater...
> works for me.

I didn't see the two wires going to your hotend at first, it looked like the LED and resistor were the only connected components.


--

Charles S.
Software Engineer
Prusa Mendel I2, RAMPS 1.4, Marlin 1.0 R2, Pronterface, Slic3r
Re: connect LED to hotend
August 29, 2012 08:49AM
Calculate the value based on the heater voltage supply.

RLed = (Vs-Vf)/If,

where Vs is the supply voltage (steady state), Vf is the forward voltage specified for the LED in its data sheet, and If is the correpsonding forward current for the LED at that Vf

That it fluctuates in brightness according to the duty cycle can be looked at as a positive through the right eyes. That the LED doesn't fail if the duty cycle goes to 100% is also a positive as well winking smiley

Edited 2 time(s). Last edit at 08/29/2012 09:32AM by xiando.
Re: connect LED to hotend
August 31, 2012 07:27PM
i probably try this weekend to hook it up....
Ill add some picures when ready
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