12V Heater Cartridges on 24V PSU?

TitanOne

Hi!

I'm currently wiring up my 3D-Printer and noticed a small problem: I have 12V Heater Cartridges, but a 24V PSU and I don't want to waste another week by buying and waiting for 24V ones. Can I somehow use them anyways?

Mysta

You may be able to use something like this - maybe wait for confirmation:
https://www.amazon.com/EPBOWPT-Converter-Regulator-Module-Transformer/dp/B01LY4RANA/ref=sr_1_5?ie=UTF8&qid=1523641168&sr=8-5&keywords=24v+to+12v

Wire the positive from duet heater to positive input on buck.
Connect input negative to psu negative.
Positive Output to one leg of heater cartridge
"Negative" on heater cartridge to negative hotend on duet.

But if you're buying something why not just buy a 24v cartidge imo. Most of them will ship pretty quickly.

DjDemonD

Yes by using a 24v to 12v buck converter. Or by buying 24v heater cartridges.

A 12v cartridge run at 24v produces 4 times the power. That's why you can't achieve this by setting PWM to 50% (as that's not actually 50% lower power) or even PWM 25% which is 50% lower power output because you're forcing the cartridge to run at 120w (when it was 30w at 12v) which is not good from a safety point of view.

As a real ghetto workaround you could run two 12v cartridges in series, but you need to do something with the second one - maybe there is something else that needs usefully heating? More likely to just be a fire risk, having a hot thing flapping about doing nothing.

Initially I used a buck converter as I had 12v fans and heaters, but now I stock 24v ones so I use 24v ones its much easier.

TitanOne

@djdemond said in 12V Heater Cartridges on 24V PSU?:

Yes by using a 24v to 12v buck converter. Or by buying 24v heater cartridges.

A 12v cartridge run at 24v produces 4 times the power. That's why you can't achieve this by setting PWM to 50% (as that's not actually 50% lower power) or even PWM 25% which is 50% lower power output because you're forcing the cartridge to run at 120w (when it was 30w at 12v) which is not good from a safety point of view.

As a real ghetto work around you could run two 12v cartridges in series, but you need to do something with the second one - maybe there is something else that needs usefully heating? More likely to just be a fire risk, having a hot thing flapping about doing nothing.

Dang, well then. Guess I will have to Frankenstein an ATX PSU I have laying around and use that until I have 24V Cartridges. Thanks anyway!

T3P3Tony

@titanone yeah its dangerous to use 12V cartidges at 24V even if you dial the power down loads. A failure that makes it go full power can melt the heatblock, have a look at this video:

https://www.youtube.com/watch?v=qVjWg2vuWzk

Electronics are not infallible so its best to start from a design that is as safe as possible (and 150W+ potential draw on the heater cartridge is not safe).

TitanOne

@t3p3tony said in 12V Heater Cartridges on 24V PSU?:

@titanone yeah its dangerous to use 12V cartidges at 24V even if you dial the power down loads. A failure that makes it go full power can melt the heatblock, have a look at this video:

https://www.youtube.com/watch?v=qVjWg2vuWzk

Electronics are not infallible so its best to start from a design that is as safe as possible (and 150W+ potential draw on the heater cartridge is not safe).

I just remembered a post about using a 24v supply for a heated bed and a 12v one for the rest, wiring it up in a way that the internal bed MOSFET could be used. Couldn't I do the same (but with the Heater Cartridges) and a 12V power brick?

T3P3Tony

Yes you can. basically the mosfets switch the ground side of the circuit so you can provide 12V power directly to the heater cartidge and then have only the Gnd connected :

https://forum.duet3d.com/topic/3288/converted-to-split-12v-24v-no-communication-help/4

TitanOne

@t3p3tony said in 12V Heater Cartridges on 24V PSU?:

Yes you can. basically the mosfets switch the ground side of the circuit so you can provide 12V power directly to the heater cartidge and then have only the Gnd connected :

https://forum.duet3d.com/topic/3288/converted-to-split-12v-24v-no-communication-help/4

Awesome!