<![CDATA[SoliForum - 3D Printing Community — [HELP] I need two power supply, one for bed and one for printer]]> https://www.soliforum.com/topic/2624/help-i-need-two-power-supply-one-for-bed-and-one-for-printer/ Fri, 31 May 2013 14:59:21 +0000 PunBB <![CDATA[Re: [HELP] I need two power supply, one for bed and one for printer]]> https://www.soliforum.com/post/24708/#p24708 the higher the value of the resistor, the less power it needs to dissipate.

You could use 'any old resistor' in a drawer for the job assuming that its acceptable in the circuit (since the resistor will end up being the top half of a voltage divider).

Traditionally in 5V microcontrollers, you use 1k or 10k or 100k depending on your mood/needs/circuit/persuasion. Due to higher voltages and current, you need to go higher to allow the resistor to have to dissipate less heat... like in say things like a guitar pedal, where you would often see 1.2M etc etc used on inputs to prevent 'popping' as it turns on/off...

Anyway.. nutshell - its a value thats a compromise and you can use anything that would otherwise work within the circuit/power constraints but ultimately its a tradeoff in so far as lower values need to burn off higher power values.... and also consume more power etc etc...

And no, I'm not that Adrian smile

]]> Fri, 31 May 2013 14:59:21 +0000 https://www.soliforum.com/post/24708/#p24708 <![CDATA[Re: [HELP] I need two power supply, one for bed and one for printer]]> https://www.soliforum.com/post/24707/#p24707 @rincewind, thank you

adrian wrote:

http://en.wikipedia.org/wiki/Pull-down_resistor

Are you "the" Adrian who wrote the prusa note!?

And does the resistance really have to be 1M? is there a range?
I am just curious how you come up with 1M

]]> Fri, 31 May 2013 14:51:48 +0000 https://www.soliforum.com/post/24707/#p24707 <![CDATA[Re: [HELP] I need two power supply, one for bed and one for printer]]> https://www.soliforum.com/post/24690/#p24690 http://en.wikipedia.org/wiki/Pull-down_resistor

]]> Fri, 31 May 2013 09:14:15 +0000 https://www.soliforum.com/post/24690/#p24690 <![CDATA[Re: [HELP] I need two power supply, one for bed and one for printer]]> https://www.soliforum.com/post/24688/#p24688 It's a pull-down resistor for the mosfet in case the board is not connected/high impedance/faulty, to avoid partial or otherwise unwanted conduction. The resistance doesn't need to be low, as a relatively slow discharge should be sufficient. Does this answer your question?

]]> Fri, 31 May 2013 07:22:43 +0000 https://www.soliforum.com/post/24688/#p24688 <![CDATA[[HELP] I need two power supply, one for bed and one for printer]]> https://www.soliforum.com/post/24678/#p24678 I am reading this build. i like the way he uses two power supplies to separate bed and printer.
http://reprap.org/wiki/Adrians_Prusa_Notes#Heated_Bed


so here is my question
http://reprap.org/mediawiki/images/9/94/Prusa-heated-bed-schematic.png
can someone explain why is R12 using 1M resistor?

]]> Fri, 31 May 2013 04:08:43 +0000 https://www.soliforum.com/post/24678/#p24678