Smoothieboard v2-mini explained.
For more info on the v2 project, see the latest update : http://smoothieware.org/blog:15
No output for heated bed?
That’s what the SSR is for. It’s a much more effective way to heat a bed than using DC from a FET.
Hey, Arthur, what are the physical dimensions of the mini board?
@Imants_Treidis About 100x80mm
So the idea is to use the line voltage (120 VAC) directly in the board heater? Wow.
@Baxsie Either that ( AC SSR ), or use a DC SSR to do it the “usual” way.
AC SSR control is actually pretty common for “large” beds, I do it all the time. But it also works for smaller beds. It’s cheaper than wasting ressources on using a PSU to bring the voltage down for no good reason.
I would argue that low-voltage heated beds do have a good reason to exist, since it is safer to wire up something where a hobbyist will not have to worry about getting zapped by mains voltage by accident…
@Erik_Cederberg Hobbyists have to handle mains voltage anyway when wiring the PSU ( on most printers ), this is just some more of that …
@Erik_Cederberg On higher end builds AC powered SSR controlled bed heating elements have been the standard for the last couple of years. Once you get over 200x200 the heat times are considerably longer as well as taking a fair amount more current from your DC psu. On a 300x300 bed heat times are a couple of minutes (or less) compared to 12-15 min for a 400w 24 volt DC psu. I someone isn’t comfortable with it they should pick another board for their build.
Also you can use a DC SSR, then you can get the safety of a DC heated bed even with this board.
Indeed a DC element with the SSR could be used but it would come at greater cost and offer slow heating times or instances where a larger element would have a difficult time reaching 110*C. I think the small format Cohesion 3D Smoothie based board would be a better fit for those build configs that desire DC powered bed elements.
@dstevens_lv we’ll also have an extension board for a mosfet for a heated bed too.
Excellent idea. The SSR headed bed users could use that board for hotend barrel fan control. I put that fan on a controlled output so it’s not running expect when the hot end is in use.