Superconductivity switches on and off in 'magic-angle' graphene

Physicists have found a new way to switch superconductivity on and off in magic-angle graphene. The discovery could lead to ultrafast, energy-efficient superconducting transistors for 'neuromorphic' electronics that operate similarly to the rapid on/off firing of neurons in the human brain.

Powering wearable technology with MXene textile supercapacitor 'patch'

Researchers are one step closer to making wearable textile technology a reality. Materials scientists have reported a new design of a flexible wearable supercapacitor patch. It uses MXene to create a textile-based supercapacitor that can charge in minutes and power an Arduino microcontroller temperature sensor and radio communication of data for almost two hours.

Transistors repurposed as microchip 'clock' address supply chain weakness

A new technique uses standard chip fab methods to fabricate the building block of a timing device, critical to all microprocessors. Currently, this timing device, known as an acoustic resonator, must be produced separately, often overseas, creating a supply chain and security weakness. The technique would allow for this timing device to be integrated with the microprocessor using standard CMOS processing, rather than later bunded with the microprocessor.

The T Flip-Flop (Quickstart Tutorial)

The T Flip-Flop is a flip-flop that can toggle its output. Toggling means switching its output to its opposite; 1 becomes 0, and 0 becomes 1. This type of flip-flop is often used in counters and frequency dividers.

In this quickstart tutorial, you will learn how it works, its truth table, and how to build one.

T Flip-Flop symbol

What is a T Flip-Flop?

Flip-flops are components commonly used to store a digital value on their output. They have a Clock (Clk) input that decides when to update their output.

The T Flip-Flop is a single-input flip-flop that either holds or toggles its output value.

Toggling, which is the reason for the “T” in the name, means changing between two states. If the output is 1, toggling will change the output to 0. If the output is 0, toggling will change the output to 1.

You can build a T Flip-Flop from other flip-flops, for example by using the JK flip-flop and connecting the J and K inputs as follows:

T Flip-Flop circuit design

Truth table

In general, you can trigger T Flip-Flops with a falling edge signal, which is the change from a digital state of 0 to 1 ↓, or with a rising edge signal, a change from 1 to 0 ↑. The following truth table corresponds to a flip-flop that triggers on the rising edge:

Clk	T	Previous Q	Next Q	Description
0 or 1	X	Q	Q	No rising edge no change
0→1 (↑)	0	Q	Q	Memory (no change)
0→1 (↑)	1	0	1	Toggle
0→1 (↑)	1	1	0	Toggle

T Flip-Flop truth table

You can see that if there is no rising edge in the Clk input, no matter what you put into the T input, the Q output will remain unchanged.

Something like the previous case happens when you have a 0 in the T input. Even if the flip-flop is triggered, if you have either 0 or 1 in the Q output it will stay that way.

To get the Toggling behavior you have to place a 1 in the T input. What you will observe is a change from 0 to 1 or from 1 to 0 every time the flip-flop is triggered. You can see this behavior in the timing diagram below:

A timing diagram for the T Flip-Flop

Building a T Flip-Flop Circuit

You can build a T Flip-Flop just by shorting the J and K inputs of a JK flip-flop. However, some websites out there suggest you build the circuit like below. But this is an incomplete circuit that will not work properly:

On paper, it seems to work. But what most websites that publish this circuit fail to mention is that you need a very short clock pulse for it to work.

Your clock pulse needs to go high, then low again before the output (Q) changes state. Otherwise, the Q output will toggle quickly between 1 and 0 during the entire positive pulse duration. You can see this behavior in the following timing diagram:

This is a problem called Racing. But it’s easily solved by using an edge-triggered JK Flip-Flop instead.

You can also build a fully functional T Flip-Flop by using a D Flip-Flop combined with an XOR gate, like this:

Edge-Triggered T Flip-Flop circuit

Example Circuit: Toggling an LED

As a practical example, you can toggle a light-emitting diode (LED) using just one push button, the T Flip-Flop, and some resistors. Check out the circuit below:

You can see how the T input is connected to 5V, which means logic 1. So every time you trigger the T Flip-Flop, the Q output will toggle its state.

The Clk input uses a pulldown resistor configuration, which means that the Clk input is 0 whenever the button is not pushed. When you press the button PB1, the Clk input will go from 0 to 1 (rising edge signal).

So every time PB1 is pushed, the LED connected to the output Q turns on or off.

To assemble the above circuit you need:

• 1x T Flip-Flop circuit (ex by combining a CD4013 and a CD4030)
• 2x 10 kΩ resistor (R1 and R2)
• 1x 330 Ω resistor (R3)
• 1x Pushbutton
• 1x LED

Questions?

Do you have any questions about this component? Let me know in the comments below and I’ll get back to you as soon as possible.

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Spin transport measured through molecular films now long enough to develop spintronic devices

A research group has succeeded in measuring spin transport in a thin film of specific molecules -- a material well-known in organic light emitting diodes -- at room temperature. They found that this thin molecular film has a spin diffusion length of approximately 62 nm, a length that could have practical applications in developing spintronics technology. In addition, while electricity has been used to control spin transport in the past, the thin molecular film used in this study is photoconductive, allowing spin transport control using visible light.

Two technical breakthroughs make high-quality 2D materials possible

Researchers have been looking to replace silicon in electronics with materials that provide a higher performance and lower power consumption while also having scalability. An international team is addressing that need by developing a promising process to develop high-quality 2D materials that could power next-generation electronics.

Polysulfates could find wide use in high-performance electronics components

Flexible compounds made with Nobel-winning click chemistry can be used in energy-storing capacitors at high temperatures and electric fields.