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Relay

Posted by jondel 
Relay
October 06, 2015 05:26AM
Is it possible to add a relay to the extruder circuit so that when the extruder is called the relay operates and if so what voltage and current would be required and would it be wired in parallel or series.
Sorry to ask this but I am hopeless with electronics.
Thanks John
Re: Relay
October 06, 2015 06:09AM
The short answer is NO.

The extruder drive would be a stepper motor circuit, a relay needs a digital DC circuit

Probably would be better to explain exactly what you want to do. guessing its trigger something when the extruder is active, and someone may tell you the best way to do it.



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Re: Relay
October 06, 2015 07:07AM
Quote
bgkdavis
The short answer is NO.

The extruder drive would be a stepper motor circuit, a relay needs a digital DC circuit

Probably would be better to explain exactly what you want to do. guessing its trigger something when the extruder is active, and someone may tell you the best way to do it.

Thanks,yes you are quite right I want to trigger a solenoid when the circuit is active and I thought a relay would have been the way to do this.

Thanks John
Re: Relay
October 06, 2015 07:11AM
Hi John, BGK is right, and the Heater (i.e. if you were thinking of turning the Fan on and off when the HotEnd is hot for example) uses Pulse Width Modulation (similar to better quality electronic model railway controllers, and the same type of signal as used by R.C. servos BTW).

If it's turning the Fan on and off that your thinking of, then check out DC42s boards, as one of the probe boards he does (he only has two left, so hurry) uses a thermister to turn the Fan on and off.
Kim


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Re: Relay
October 06, 2015 07:11AM
Actually, you can. This gcode [reprap.org] causes the FAN0 output to be driven with the specified PWM value whenever the extruder drive is running forwards. So you could set the PWM to 255 and a connect a 12V relay or solenoid (up to about 2A) with a flyback diode in parallel to the FAN0 pins. Obviously you can't then drive a print cooling fan on a Duet 0.6 because the FAN0 pins won't be available for one.

Edited 1 time(s). Last edit at 10/06/2015 07:14AM by dc42.



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Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
Re: Relay
October 06, 2015 07:34AM
Quote
KimBrown
Hi John, BGK is right, and the Heater (i.e. if you were thinking of turning the Fan on and off when the HotEnd is hot for example) uses Pulse Width Modulation (similar to better quality electronic model railway controllers, and the same type of signal as used by R.C. servos BTW).

If it's turning the Fan on and off that your thinking of, then check out DC42s boards, as one of the probe boards he does (he only has two left, so hurry) uses a thermister to turn the Fan on and off.
Kim

BGK wants to operate a solenoid when the extruder motor is running rather than when the hotend is heating.

Dave
Re: Relay
October 06, 2015 07:38AM
me? no the OP said extruder, I presumed he was talking about the extruder motor, as the hotend is generally 'always running' under PID control. to do



RepRapPro Mendel 3 Tricolour
RepRapPro Fisher
-Carbon Arms
-Easy adjust Carriage+effector
-axis stiffness mods
HE3D -600 delta
-Duet 0.8.5
-PanelDue
-DC42 Height probe
-RobotDigg metal components
Simplyfy3D
RS Design Spark CAD
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