Common positive

Can I use a common +24VDC for multiple hotends and turn each of them off and on using only the negative connection on multiple mofsets? Rambo boards do this but I’m not sure about Smoothieboard.

Imported from wikidot

I’m not sure I understand what you mean, would you have an example diagram ?

this can be done as my delta is working on the same principle.
make sure you cables with the right tickness

Basically, I want to reduce the amount of wires going down to the end effector of a delta machine. This would be done by running a common positive 24vdc from the power supply to the end effector to power the heat cartridges, hot end fans, layer fans, etc. Switching them on and off would be done by individual ground wires run to the mofsets.

Mmh I’m not sure if that’s a good idea, or not, or it could even be how you are supposed to do things.

I’ll let somebody with more smarts answer.


Si je puis me permettre il me semble que c’est le négatif moins- qu’est commun le positif est commuté par les mosfets

I’m going to give this a shot this week. If it works the hotends and fans will be powered by one positive 24vdc lead with switching handled through individual negative leads to the mofsets. Hopefully this will reduce the bulk of the wire/bowden tube bundle on my deltas. I’ll do some probing with a multimeter before the actual application of loads. It should work, but the common may be the negative rather than positive.

I did some initial testing and it appears that the positive is indeed common and the negative is switched by the mofset. I’ll hook up some loads and see how that goes next.

OK, I tested it out with real electrons and loads today. I ran a line from the positive connection on the small mofset input which had both connections positive and negative connected to the appropriate power supply outputs to the end effector. There, I connected the layer fan, hotend fan and heater cartridge. I attached the negative wires from each of those individually to the negative terminals of the small mofset outputs. Each item performed exactly as if its positive and negative wires were run from the item to the individual small mofset outputs. With dual extrusion, the resulting setup would result in eliminating 5 wires running to the end effector. Six if you run an LED. Repeat, if you like on the large mofsets.

Désolé en français, si vous regardez les plans de la smoothieboard par exemple les mosfets et Q4 et Q5 ont la “source” commune reliée au moins Vbb ils commutent sur leur drain le + plus Vbb et ainsi pour tous les mosfets de la carte donc vous avez une ligne commune qui sera le négatif de votre alimentation le moins est commun pour toutes les alimentations Vbb 5v 3.3v…. ou alors je ne sais pas lire un schéma.