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Heated bed power supply

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Hello,

I have a reprap Mk2 heated bed PC and and chinese 24V / 400W (16.6 A) power supply.

- as far as i understand, Ultimaker Wiki (

http://wiki.ultimaker.com/Heated_Bed

) says that i can replace the stock ultimaker power supply with my chinese one, in order to to power both the ultimaker and the heatbed (through the headbed output of the UM electronic card). The wiki states that the replacement power supply "should be 19-26V and have a power of 150W+The max heating power of your heated bed", which is the case

- but the reprap Wiki (

http://reprap.org/wiki/Ultimaker%27s_v1 ... ifications

) states that the V1.5.4 UM Electronic card "Runs from 15V to 19V"

So my question is: Can i safely power my UM electronic with my chinese power supply (even if 24V > 19v) and just plug my heat bed to the UM electronics heatbed output?

Alternative may be to first regulate the 24v to 19v, but i don't wan't do to it if not necessary.

I understand that i can get an additional 12V power supply just for the HB and keep the stock 19v power supply for the UM, as indicated in the wiki, but i would rather have only one power supply.

Thanks in advance

JP

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I'm not sure what component limits the "19V max" of the ultimaker board. I'd asume you cannot do this until you verify that it really can be safely done.

There are mosfets that go up to 20V. There are capacitors that officially go up to 24V. All these would make it very risky to run the board at 24V. Isn't there an adjust screw that you can make the 24V supply give a little less? (Assume that this will reduce the power-rating, as the current rating will remain the same).

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Hello,

Thanks for your answer.

Yes, the chinese power supplies i buy from eBay usually have a trim potentiometer to adjust the output voltage. I have not yet received the 24v power supply, but i guess it would be possible to go down to 20v more or less.

Nevertheless, i saw on the Ultimaker google group that the stock power plug and switch are not rated to handle the current that will flow through with the heatbed on. So i think i will eventually take the dual power supply route, as describred in the wiki (the stock 19v for powering the machine, and a separate 12v for the heatbed).

Regards

JP

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Yup, i saw your post on the other thread, and read your explanations (

http://flashgamer.com/arduino/comments/ ... -ultimaker

) with great interest. Thanks!

As a matter of fact, your page shows the printed accessories you used, but i was unable to find a link to them. So thanks again for providing this link above!

Regarding your question about the use of a relay, a guy built its heated bed by following the ultimaker wiki instructions (

http://www.digitalspirit.org/blog/index ... -Ultimaker

, but it's in french :)

JP

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Yes, i agree that cascading another power component (either a relay like you did ou an additional external mosfet) is better for temperature control and protection of the ultimaker electronic.

The french guy followed the wiki instruction for direct connection of the heatbed to the ultimaker card mosfet.

I was initially planning to do the same, but reading more carefully the wiki, it says that 'it should work, but was not tested'...

I will think about it....

JP

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Hi,

I installed a heatbed mk2 with an extarnal power suply of 12v 30 a, the powersuply is controlled by a 3-30v mosfet solid state relais. True the ultimaker blog i was able to connect the thermistor 100k and its working fine.

I use replicater g 026 as software.

My problem :

Iwhen i start up with the regular soft 5d build 1 all works fine except the controler of the heatbed, even when it is not activated it flickers every second, when i activate the heatbed true my replicareg it flickers a little faster but it does not work like the hotnose... Can anyone advise me what to do ? I have used all possible soft and firmwhare available but coulnd't solve my problem.

Thanks for any sugestions... Ledlab team

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So, has anybody now done it with a single Power supply? I just can not get to like having a second power supply, because i already hate all the cables hanging around.

The Video Benrhard Kubicek as posted on the wiki :

shows a quite nice, long and small power supply that could fit under the Ultimaker. It is stated that it is 300W at 24V and that on the video you see the additional suicide print.

So i think there is nothing to be changed between the power supply's output and the Ultimaker Board. Am I right here?

The one thing i'm wondering is what power supply that is on the video, or where to find a similar one.

All i could find are those ATX power supplies but they are way to fat.

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Bernards power supply is an industrial one. Farnell seems to sell them. At the category "Power & Line Protection -> Power Supplies Switch Mode - Enclosed". But a 300W supply 24V sets you back well over 600 euro...

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Am I right in thinking that the limiting component here is simply the regulator? I understand that even with the stock PSU with the Ulticontroller attached it is pushed to it's limit since it doesn't have a heatsink on it. The new fan shroud that comes with the Ulticontroller has an additional cutout to help cool it. I also added a small heatsink (similar to the ones on the stepper drivers) just because I happened to have one around.

If I go with a heated print bed I think I would want a single supply solution, and 24v PSUs look like the likely answer, but it seems that the extra 5v might just put the 7812 over budget on hear dissipation. However, I don't see any reason that I can't drop in a 12 switching regulator (one of these:

http://uk.rs-online.com/web/p/switching ... s/6727142/

). That should provide the same amount of power to the UM electronics without producing excessive heat as the voltage increases like the linear.

Cheers,

Troy.

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