Heater catridge voltage
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Is there a way to safely drive 12v heater cartilages on a 24v system? I know in Smoothie I could cut the PWM in half and it would work fine. The reason for asking is I have about 10 of these from my last printer that was a 12v, and the new one is running on 24v. I hate to waste things. I measured the resistance and they were definitely different, but so much so that I think I may have just been a bad unit. 3.4 vs 14 and change in Ohms. I skimmed through the RepRap G-code page but nothing jumped out at me.
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Those resistances sound about right.
P=V^2/R so
P=12^2/3.4. =~42W
P=24^2/14 =~41WHowever running a 12V rated heater cartridge at 24V and relying on the PWM to limit the power is asking for trouble. A failure of the MOSFET on, frozen firmware etc could cause:
P=24^2/3.4 =~170W through the hotend.
This is a recipie for a fire.Even 40W is higher than necessary for a normal hotend.
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Thanks, I'll order some of the right thing since I like having spares on hand.
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You can use a voltage converter there are a lot of threads about how to wire one so that you still have pwm control.
