Power Outage Protection for 3D printers

view4 view3 view1 schematic


This device is a protection against power outage for a 3D printer. If the power goes out, the printer will not be turned back on when the power comes back.

The scenario I have experienced is the following. I was printing an object using a laptop. While printing, the power went out. The Arduino stayed powered by the laptop. When the power came back, the extruder was turned back on but no filament was pushed in by the extruder. The result was a ruined J-Head. The filament was burned solid in the extruder. I had to replace it.

When power is applied to the device, the push button must be depressed to have power on the output terminal.

Be careful when building this device. It deals with a lot of currents: 16A per printer. It is enough to catch on fire if not assembled properly or the right components are not used.

This device can drive only one device at the time. If you want to drive two printers, you shall replace the wiring gauge, the relay, the switches, etc.

Shame on me! I did not print the case. This case cost less than $5. It simply does not worth it designing one and printing it.

Bill Of Materials
– 1 relay NVF4-4C-Z30A-12VDC. It is a relay used for cars. [K1]
– 1 bolt and nut to attach the relay to the case
– 1 four posts terminal [CONN2]
– 1 two posts terminal [CONN1]
– 1 switch with a 12VDC light [S3/GL1]
– 1 push button normally open [S1]
– 1 12VDC light [GL2]
– 1 switch to select which printer is active (The one I got has a neutral position.) [S2]
– 1 12 ohms 1/2 watt resistors [R2]
– 2 36 ohms 1/4 watt resistor [R1/R3]
– Solderless terminals.
– 6 feet of 12 AWG wire
– 1 Hammond case 1591XXSSFLBK

The resistors are required only if you are using a 13.8VDC power supply.


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Copyright 2012-2013 by Claude Théroux