How does your Toaster work?
Hey gadgeteers, Happy Wednesday!
Last week, I went for an Apple Vision Pro demo at one of the Apple stores and loved their spatial video feature.
Let’s look at how a simple toaster works this week. I aim to write my newsletter issues in a way one can follow them while traveling on a bus, having a coffee, waiting for food, etc. Let’s jump in!
How it works: 15-second answer
A toaster operates by compressing a spring mechanism when the button is pushed down, activating an electromagnet to hold it in place. This electromagnet is powered by the circuit, ensuring the bread slice remains within the toaster. Meanwhile, current flows through nichrome wires wrapped around a mica sheet. These nichrome wires turn red hot and generate heat due to their high resistance to toast the bread evenly.
Answer to the question I posed last week
Last week, I asked what is the core technology used in mechanical weighing machines. They use springs and levers primarily to measure the weight.
How does a Toaster work?
I use a toaster every single day. So, I was curious to know how it works, and here it is!
Placing the bread slice into the slot:
When we insert a slice of bread into the slot and press the lever to start toasting, we’re basically compressing a spring mechanism. This spring force is responsible for the bread slice popping back after completion. And something interesting happens when you push it all the way down with the toaster powered on…
Figure 1: Lever compresses a spring and closes the copper-colored contacts to activate the electromagnet to hold it in place. Source: Technology connections
Electromagnet holding the bread slice in place:
The lever pushes a contact strip to complete the circuit. And an electromagnet is activated to hold the lever in place. An electromagnet is a magnet that can be turned on and off using electricity. The circuit powers the electromagnet to attract a metal piece of the lever and this is why the lever stays in the bottom holding the bread in the slot fully immersed.
Heating element:
At the same time, current starts flowing through the circuit to start the heating process. A long wire made of nichrome is part of the circuit and it’s coiled several times around a mica sheet and placed on either side of the bread slice as seen in Figure 2 below.
Figure 2: The red strips of light are the nichrome resistive wires turning hot and wrapped around a mica sheet. Source: iFixit
This wire turns extremely hot and radiates heat to heat the bread when current is passed through it. The bright reddish-orange light you see inside a toaster is the nichrome wire.
But how and why does it turn really hot?
Any resistor with a high resistance causes more resistance for the electrons to move around and this friction causes a lot of heat. Nichrome has a very high resistance and here is why…
Figure 3: Parameters for a resistor’s resistance
High Length and Resistivity: Nichrome’s resistivity coefficient is very high (~70 times more than copper) and winded all around on the sides of the bread making the length very long.
The low cross-section area of the wire: It’s made of thin wire to decrease the cross-section of the area. All these make this nichrome wire a suitable candidate to heat the bread.
Support for heating element:
Mica sheet (see Figure 2) is used as the base for nichrome wires to be coiled around as mica gets hot quickly, heat evenly, and cools quickly once turned off making it ideal for our needs. For this reason, many consumer electronics products also use mica sheets in their appliances.
Different toast settings using a dial:
The dial we turn in after pressing down the lever is a timer in modern toasters. A microchip computer manages this timing and deactivates the electromagnet holding the lever in place. Because of the loaded spring, this makes the bread pop back up once the timer expires. Different dial positions set a different timer countdown for the circuit to use.
This is how a toaster works!
Question of the week
What other consumer electronics products use mica to heat and cool quickly? Reply to this email with your thoughts, and we’ll discuss.
Gadget of the week
Smart collar for dogs: Minitailz allows you to monitor your pet’s heart health, position, activity, and appetite. These are biometric health collars for dogs with activity tracking & GPS. It looks like a power bank and comes with a ring for effortless clipping onto any type of strap.
That's all folks. Thank you for reading!
Have an amazing rest of the week, and take care!
Until next to next Wednesday,
Chendur
