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What it does Diodes clamp harmful inductive spikes when relays de-energize, protecting surrounding circuitry. How it works When relays de-energize, their coil (an inductive element) causes large voltage spikes at the relay-MOSFET junction. Diodes are used clamp this voltage spike to a safe level so it does not exceed the drain-source voltage rating (VDS) of the MOSFET, potentially damaging the device. Here's how it works. De-energized (initial state). When no voltage is prese

I recently designed a circuit using an ATtiny84A and found it difficult to locate information from Microchip Technology regarding connector pinouts, wiring diagrams, and connector part numbers for In-System Programming (ISP) via the Serial Peripheral Interface (SPI) using an Atmel-ICE programmer. This article presents a working circuit, design description, and bill of materials (BOM) for others to reference when creating their own ATtiny84A-based circuits to save time and gua

What it does This circuit converts a noisy switch input signal to a clean, debounced logic signal. How it works Assume the circuit has reached steady state, with C1 fully charged and TP1 at 0 volts. When S1 closes, its contacts momentarily bounce (before fully closing) causing paths A and B to alternatively charge and discharge capacitor C1 during the bounce period. Since R2 is much larger than R1, path A takes longer to charge C1 than it takes path B to discharge C1, essenti

Quantum sensors are commercially available, and the market is growing rapidly. The timeline for quantum sensing varies by application, but the consensus among researchers and industry analysts is that several categories are already transitioning from research to deployment. Commercial quantum sensors can be found at Vector Atomic Inc., Q-CTRL, and Infleqtion. Quantum sensors provide a step-function in performance over classical sensors and are ideal for navigation, medical im

Rechargeable battery technology is advancing rapidly. Cutting-edge chemistries and constructions such as sodium-ion, solid-state lithium metal, and lithium-ion with silicon anode promise to overtake the performance of lithium-ion batteries soon. The following table compares lithium-ion technology (as baseline) with these emerging technologies, highlighting the pros and cons of each. Parameter Lithium-Ion (Li-ion) Baseline Sodium-Ion (Na-ion) Solid-State Lithium Metal (LMB) Li

“A sodium-ion battery is a rechargeable energy storage technology that uses the flow of sodium ions (Na+) between the anode and cathode during the charging and discharging processes. Although the active materials are different, its mechanism is comparable to that of a lithium-ion battery” [Puteri]. Sodium-ion batteries are chemically stable and have a simplified supply chain. They have excellent cycle life and fewer thermal-runaway concerns than lithium-ion batteries. Sodium-

Using the right equipment to solder electronics to circuit boards makes the experience more enjoyable and produces higher quality results. In this post, we describe the equipment and settings that we use, and recommend to others, for soldering surface-mount (SMD) and through-hole components to printed circuit boards like a pro. Weller WESD51 Soldering Station Soldering Station Start with a quality ESD-safe soldering station like the 50-Watt Weller WESD51 or the 70-Watt Weller

Quantum sensors provide a step-function in performance over classical sensors and are ideal for medical applications because of their unique sensing capabilities. Quantum sensors are an order of magnitude (~10x) more sensitive to environmental changes than classical sensors thanks to the sensitivity of quantum states. Where classical sensors fail to detect infinitesimal changes in the environment, quantum sensors can pick them up with ease. Goal: Decode neural activity in liv

General Instructions Use this parametric design guide to create a functional, and safe, resistor-capacitor (RC) snubber circuit for use with 120 VAC 60 Hz single-phase motors that are controlled by an upstream switching device. Who should use this design guide This design guide is meant for hobbyists, circuit designers, and engineers who are designing an RC snubber from scratch or analyzing an existing design. Use-case and circuit topology Use this design guide for RC snubber

The “silicon (Si)-based anode has emerged as the most promising anode material for next-generation lithium-ion batteries (LIBs) due to its high specific capacity, suitable operating potential and abundant natural reserves” [Zhao]. These batteries are seen as a bridge between conventional lithium-ion and future technologies (e.g., solid-state). They allow fast charge times, have decent cycle life, and exhibit great energy density. Silicon is also non-toxic and abundantly avail

Solid-state batteries are getting a lot of publicity because of their remarkable performance potential over existing battery technologies. According to Shimabukuro, “solid-state batteries represent a major advancement in energy storage technology because they replace the liquid or gel electrolytes in traditional lithium-ion batteries with solid materials (like ceramics or polymers).” This allows them to be non-flammable and thermally stable. They can charge incredibly quickly

When designing a printed circuit board (PCB), there are many options for core, prepreg, and copper materials and thicknesses. The table below provides a guideline for common materials and thicknesses for both 2- and 4-layer PCBs. Note: Standard PCBs are nominally 1.60 mm thick.

CDMA signals have the property that when a received message is compared (convolved) with a replica stored in the receiver and they match, a correlation peak occurs. Otherwise, no peak occurs. This type of detector is commonly referred to as a Matched Filter. The figures show the auto- and cross-correlation for two unique 31-bit CDMA messages generated using Gold-code pseudo-random noise (PRN) encoding when processed through a Matched Filter.

I think it’s awesome how bandpass filters make modern communication possible by controlling the electromagnetic spectrum. Bandpass filters constrain signals to a specific frequency range, allowing users at different frequencies to share the same transmission medium (air, copper) without interfering. The image shows a communication signal before and after filtering. Without bandpass filters, modern communication would be unreliable or impossible.

I was curious about Gold codes, so I generated some from scratch to understand them better. Gold codes are a pseudorandom noise (PRN) sequence used in CDMA and GPS technologies. They function as unique "fingerprints" for different transmissions, allowing multiple users to share the same frequency without interfering with one another. Results: the figure shows two (of eight) optimal 31-bit Gold codes generated from two well-established maximum-length sequences (m-sequences).

In engineering, some of the most basic concepts are often the most powerful. Take BPSK (binary phase shift keying), for example. We can encode a binary message by simply changing the phase of a carrier signal from 0 degrees to 180 degrees. BPSK is used in GPS, satellite TV, and modern communication systems. The figure shows a BPSK message of 101110.

I found it interesting that CDMA signals have a rounded shape due to bandpass filtering. The rounded shape allows overlapping CDMA signals (orange and blue) to be detected because when one signal is low, the other has an opportunity to peak through and be detected, even in the presence of noise (green).

I was curious how the detection quality of CDMA signals at a receiver would change as the receiver moved away from one transmitter toward another (i.e., same frequency, same transmit power, different pseudo-random noise (PRN) codes). Logically, when the receiver is halfway between two transmitters, the received power levels would be the same. Would the signals then interfere with each other and cause both to drop out, or is CDMA robust enough to handle the interference and al