DIY 3D Printer from scratch – Power Supply
Welcome to 3DPrinterChat.com, this article is part of the DIY 3D Printer from scratch, and we will learn how to choose the best 3D Printer Power Supply.
What are the available kinds of power supply?
There are two main kinds of power supply available, we will focus on the Switch-mode because of its efficiency, but is always good to know the other option.
Switch-mode power supplies:
Nowadays practically all power supplies within the power range required by RepRap printers (250~350W) are switch-mode power supplies (as opposed to linear power supplies, which are considered technologically outdated).
Switch-mode power supplies have relatively complex circuits that convert mains AC electricity to the DC voltages required by RepRap steppers and electronic circuits. The main advantage of an Swith-mode power supply is its high-efficiency in converting energy. for more information you might want to take a look at this full explanation
There is also this video, it talks about step-up converters, they are NOT the same, but the logic behind it is, and its easier to understand:
Linear power supplies:
This kind of power supply usually use a transformer to reduce the AC voltage, to about 16V AC, then a rectifier circuit will take care of converting the AC voltage into DC, and a stabilizer circuit will make it stable.
The disadvantage of this system is its low efficiency, high cost and taking huge amounts of space. You can read more about this here
How to choose the you switched power supply model?
There are two main models of switched power supply available, the ATX and the INDUSTRIAL (also known as CCTV or OEM). we wont talk about Xbox/Playstation power supply because they are simply the same, with less power output and worse cooling.
Industrial PSUs are switch-mode PSUs designed to supply a fixed DC 12V or 24V rail with high current capabilities (1A to 100A or even more). In the last couple of years, due to the development of LED lighting and CCTV, they have become relatively inexpensive and are now widely available. There are many models available, some with extremely good output, some not. you might want to check the reviews that the PSU got.
- Cheap (30A is about 20-50$)
- Regulated output voltage between 9-16v
- Regulated fan (less noise when not in use)
- Easily replaceable (under 5 min)
- widely available
ATX PSU’s also are switch-mode PSUs designed to supply some fixed voltages to be used in a computer. In our case we only use the DC 12V output. Usually the ATX have a medium range current capabilities (from 20 to 40A), that are the required to run a computer properly. ATX power supply have the advantage of being extensively used, every computer has one, for this reason they are extremely cheap, while having great protection and output stability.
- Cheap (400w is about 20-50$)
- Wide range of fixed voltages ( -12V; -5V, 0V or GND, +3.3V; +5V and +12V)
- Great protections embedded (short-circuit, wrong voltage input, wrong frequency input)
- Easily replaceable (under 5 min)
- Power factor correction
- widely available
- can be turned off automatically at the end of a printing (see more)
- it takes more space.
- The total output is divided between all the voltages, meaning: in a 500W PSU, you might only have 300 available to the 12v rail.
- Soldering skills needed (or at least tools and a connection board) to assemble and make it work.
Power factor correction, why this matters (or don’t) ?
Power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit. This is confusing right? Let me explain better, take a look at this two kinds of power:
- Working Power – which is converted into useful work such as turning motors or producing light. This power is also called “Active” or “Real” power. It is measured in watts (W).
- Non-working Power – which doesn’t do useful work and is only used to “energise” the magnetic or electrostatic properties of the equipment. This power is also called “Reactive” power. It is measured in volt-amperes-reactive (VAr).
Understanding the PFC
Now we will use the beer analogy:
The total content of the glass – beer and froth – represents the Total Power.
The froth, representing Non-working Power, does nothing to quench your thirst.
The beer, representing Working Power, does quench your thirst.
To get greatest value for money from the glass of beer it needs to be full of beer with no froth.
Now, going back to electricity terms:
Now you must be thinking: “Right, i understood why a PSU with power factor correction is good, but if i remember well, only inductive or capacitive loads gets affected by this, right?” Yes. the steppers are inductive loads, and although they wont create a big phase dislocation, the price of an PSU with embedded active correction is almost the same as one without.
TL;DR: It’s good to use a PSU with PFC, but not mandatory!.
PSU Efficiency and why it matters!
How much watts do i need?
3- For a printer with 30×30 Heated bed: 600W
4 -For a printer with 40×40 Heated bed: 200W+, Bed powered by 220v AC using a SSR to control it.
Heated bed too slow to heat? check some possible fixes
3D printers are catching fire (literally).