Power supply advice please

DjDemonD

A solid state relay - a device to switch a large current using a small one. Used when you power your heatbed from mains power with a DC-AC SSR, or if you buy a DC-DC SSR from a second DC power supply. Usually they isolate the low current and high current side optically. A good idea if your print bed is larger than the usual 200x200mm as to achieve the desired 0.5W/cm2 requires a larger heater which draws more current than most controller boards can handle.

They can handle low frequency PWM for more precise control of bed temperature.

It is also possible to use a mechanical relay, but without PWM using bang bang mode.

cap

thanks for this info i must off edited my above statement as you replyed

cap

ok so had a look at ssr WOW how many there a lost here
can you recommend a good one with out killing my pocket
are am i looking for a

ssr 40a dc ??

iDevelo

@cap:

no im not whats a ssr

edit

ok i did say im no engineer but i do love this guy i think if you sent this guy a board asking him to do full review and setup blog it would help your sale to low tech peeps like me and boost your sales
https://www.youtube.com/watch?v=TiEwNf1H_Tc
https://www.youtube.com/watch?v=TiEwNf1H_Tc

thanks for the help good job ive only got low hours with my prnter plugged in ill get this sorted with out going stupid money what would be a good ssr to get

I think you sent Tom one not long ago didn't you Tony?

cap

i wish i had money to give away m8 sorry not me but i have ask before

cap

would this do me
http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=30

Dougal1957

@cap:

would this do me
http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=30

No it wont as that is for an AC bed think you need one for DC so look at

http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=288

Doug

cap

hi again thanks for your help
i am trying to find one local but i do not fancy my chances

also ran into this may help other so ill post it here
http://sublimelayers.blogspot.co.uk/2016/03/how-to-choose-ssr-to-drive-your-heated.html

think ill have to pay more for postage than i will for the part lol

Dougal1957

where are you?

cap

uk
cost £29.31 pound shipped

Dougal1957

OK I think RS do some decent ones but not looked into it as I only ever use AC Heaters on My Printers so a bit of Valots drop is insignificant however at DC it is a major problem as you have found out?

Doug

cap

http://www.auberins.com/index.php?main_page=product_info&cPath=2_30&products_id=288
well ive read a couple of poeple have ran into problems with 12v dc heaters (doh live and learn) and that the linked ssr above work well with just a heat sink
so my thinking is run a 32amp 400w psu via ssr to run my 12v 280w heat-bed leaving a big safety margin 40%
and then run my 25amp 300w psu to run my duetwifi board with all attached bits also leaving a large safety margin

im thinking ill let it run like this for a year then ill iver by better psu when funds arrive are recycle the psu into new projects

any safety tips would be gratefully received
are safer ways to achieve me goals

dc42

See the section on connecting a bed heater on the wiki. I included SSR recommendations in it.

Printers with beds larger than 200mm square are usually run with 24V power, to keep the bed heater current to manageable proportions. For example, if you had a 24v 280W bed heater instead of 12V 280W, the current draw would be 11.7A which is within the rating of the Duet WiFi.

cap

well its all ordered now and in the post so ill try ill move everything into the shed for a good long test run it can make big smokey mess at the bottom of the garden (worst case) and ill fit a big red switch in shed to kill all shed power
and anther big red switch at back door

Dougal1957

The Single 32 amp PSU should be able to manage the whole lot to be fair sure DC will be along to give his advise soon enough.

The Auberin ones should be fine mounted to just an Alloy plate I think I reckon you will need to sink approx 2 watts of heat away from it so not excessive Remember you can use the Heatbed output from the Duet to switch it on and off and the output of the PSU would have the O/P of the SSR In series with the Bed.

cap

hi only me the ssr is in the post and i get how to wire the ssr and the power supply to the board but what i cart find is do i need to change anything in the config file for it to work

dc42

You don't need to change anything in the config file to use an SSR to control the bed.