How to connect two 24V PSUs?
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Hi gents,
I have a 300W silicone heater for the bed and want to feed it with a separate PSU. I have adjustable Meanwell 350W PSUs, but I don't think it's a good idea to wire them in parallel.
How can I power the bed separately and still control it through the bed -MosFET? (Without a dc/dc SSD)I'll try to sketch up my solution and post it here, but would like to know how others have done it in the past.
THX -
@o_lampe If your MosFET (and Fuse) allow to deliver 300W, then it should be possible to connect the GND's of the two PSU's (need a prober Wire!).
Then connect the heatbed between the second PSU+ and the MosFET- (Bed- on board)I'm not 100% sure if this will work!!
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@cosmowave
That was also my idea.
But I'm not sure how PID tuning would work then? Vin of the bed is unknown...
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@o_lampe said in How to connect two 24V PSUs?:
But I'm not sure how PID tuning would work then? Vin of the bed is unknown...
But the two Vin's should not be very different..
Do you need a very accurate PID tuning for the bed? -
Personally, I would err on the side of caution.
For approx £18, I would go with a DC-DC SSR. (Yes I did read that you did not want to use one!
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Mankati FSXT+, DeltaTowerV2, E3D MS/TC
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@o_lampe said in How to connect two 24V PSUs?:
But I'm not sure how PID tuning would work then? Vin of the bed is unknown...
Well on my printers I have 120 VAC bed heaters controlled by AC SSRs.
PID works fine even though Vin is not used for heating.
Frederick
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@cosmowave Hello may I join in and humbly ask if it is possible to power the silicone heater pad with a mosfet or does it need to be a SSR? Ive read that a SSR is a MOSFET in a fancier package? Ive got zero problems getting a good SSR cause Im planning on getting a 400mm X 400mm Silicne Heater Pad for my Anycubic Chiron 3.0 build powered by a D3M5+ of course so am curious as to what is the deal with the SSR vs the MOSFET for the purpses of heating the bed or nozzle for that matter. TIA!!!
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@pickett You can power your bed with a suitable mosfet. That's possible.
If you'd like to use a AC bed-heater then a SSR will switching allways at 0 volts. So you have no "switching peaks"
Sorry, my english is not good enough to explain it better! -
@pickett If your heater needs higher voltage than the Duet3 is rated for, you need an external switcher.
A dc/dc ssr is an array of Mosfet, but for AC you'd need an AC-SSR. -
@o_lampe said in How to connect two 24V PSUs?:
@pickett If your heater needs higher voltage than the Duet3 is rated for, you need an external switcher.
A dc/dc ssr is an array of Mosfet, but for AC you'd need an AC-SSR.You do need to be careful with DC-DC SSR's due to there on resistance (most of the cheaper ones use Triacs I think and tend to have a quite high Volts drop which leads too a lot of energy being lost in the SSR itself) IMHO a good Mosfet is the preferred for a DC bed and a Zero Crossing SSR for AC Beds.
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@dougal1957 thanks sorry for the late reply as I had been really busy with the kids. Anywho I am seeing some Zero Crossing SSR's and I guess I need to educate myself a bit more on SSR's in general. Ive found one by Uxcell but it is only 12.95 USD which is definitely a good price and a lot of the reviews are great but if there is anything Ive learned about great reviews on Amazon doesnt always mean they are real but these do sound authentic from a lot of different users. Anyways the SSR I have spoken about is an DC to AC SSR as the Silicone Heater Pad Im going to buy is a 120v AC bed which I know will work terrificly and can hardly wait to get it as Im finishing up my build of my Anycubic Chiron with a Duet 3 Mini 5+ and other nice components though with most things in life there are even nicer components than the ones Ive got to be had but that is life I guess or me anyways always wanting something bigger and badder lols. So is the Zero Crossing SSR an AC to AC SSR?
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@pickett zero crossing just means that it switches the AC output att the zero points of the wave form so it applies to any SSR that switches an AC Load (so DC-AC sir's) I have never seen a AC-AC one tbh not that that means they don't exist I just don't know.
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@pickett said in How to connect two 24V PSUs?:
Ive found one by Uxcell but it is only 12.95 USD
I would say that is overpriced.
Take a look here: https://www.auberins.com/index.php?main_page=advanced_search_result&search_in_description=1&keyword=ssr
There is a range of AC and DC SSRs in a range of power ratings and they don't cost a fortune.
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@dougal1957 yeah wow I guess an AC to AC SSR would be not only redundant but dumb lols "hey let me get a plate for my hamburger and a plate for the buns to sit on so I can eat a hamburger wrapped in wax papers lols!!!!!!!" ok ok sorry I didnt realize what I said til you said something lols its all good anyways ok thanks man I appreciate the bit of info I really do!!!!
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@phaedrux thanks man Ill look into that and see what I can come up with over here in the US Market thank you though I really appreciate it I really do!!!!
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@pickett said in How to connect two 24V PSUs?:
over here in the US Market
Auber Instruments is US based. Georgia I believe.
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@o_lampe for a dc heatbed I would probably go for a external mosfet...this way you have a dedicated psu for your heatbed and a seccond psu for everything else...in any case I use alot this type of mosfet powering the heatbed just because is cheap ro buy 2 psu with lower watts(24v 350w) than to buy a bigger psu(24v 600/700w to meet all the power drain requirements)
https://m.banggood.com/3PCS-60+50mm-Hot-Bed-Power-Module-Expansion-MOS-Tube-For-3D-Printer-p-1272663.html?utm_source=googleshopping&utm_source=googleshopping&utm_medium=cpc_organic&utm_medium=cpc_bgs&gmcCountry=PT&utm_content=minha&utm_content=dcr&utm_campaign=minha-pt-en-mb&utm_campaign=dcr-ssc-pt-en-newcustom-ncv65-0720¤cy=EUR&cur_warehouse=CN&createTmp=1&ad_id=534534084655&gclid=Cj0KCQjwkIGKBhCxARIsAINMioJpFBfRNwRKoGiy9kqHrrPNd-pPVbN9NGLfFDIM7ZsvrQiMCRCqv1AaAo1xEALw_wcB
