Sensing current on the high side

Michael Dunn @ edn.com writes:

At their heart, the majority of DC current sense circuits start with a resistance in a supply line (though magnetic field sensing is a good alternative, especially in higher-current scenarios). One simply measures the voltage drop across the resistor and scales it as desired to read current (E = I × R (if I didn’t include this, someone would complain)). If the sense resistor is in the ground leg, then the solution is a simple op-amp circuit. Everything stays referenced to ground, and you only have to be careful about small voltage drops in the ground layout.

Sensing current on the high side – [Link]

Tiny LED Time Watch

tinytimewatch

David Johnson-Davies designed a minimalist ATtiny85-based watch using 12 LEDs, arranged like a clock face, to show the time in analogue-style. He writes:

To show the time you press the button on the watch face, and the time is then displayed for four seconds. It lights one LED to show the hour, and flashes another LED to show the minutes to the nearest five minutes, like the hour and minute hands on a clock. If only one LED lights up you know that both hands are pointing to the same hour mark.

Tiny LED Time Watch – [Link]

RELATED POSTS

PCB Rax – A modular system for holding circuit boards

pcb-rax-01-1024x657

The PCB Rax is an easy to use, versatile printed circuit board holder for repair, prototyping , and assembly that can hold nearly any shape of circuit board. Check the details on the link below.

Not all circuit boards are rectangular. PCB Rax was designed to hold all kinds of different shaped circuit boards, from circles to christmas trees, and everything in-between. PCB Rax comes standard with 10″ connecting rods that can hold rectangular boards up to 9-1/4″ x 8″, and odd shaped boards up to 6-1/2″ x 8″. For larger projects the connecting rods can be replaced.

PCB Rax – A modular system for holding circuit boards – [Link]

Low-cost current monitor tracks high dc currents

dc-current-measure

Susanne Nell @ edn.com has a design idea on how to measure high dc currents.

To measure high levels of direct current for overload detection and protection, designers frequently use either a current-shunt resistor or a toroidal core and Hall-effect magnetic-field sensor. Both methods suffer from drawbacks. For example, measuring 20A with a 10-mΩ resistor dissipates 4W of power as waste heat. The Hall-effect sensor delivers accurate measurements and wastes little power, but it’s an expensive approach to simple current monitoring.

Low-cost current monitor tracks high dc currents – [Link]

Top Ten Online Circuit Simulators

Online circuit simulators are getting more popular day by day. Electronics hobbyists, as well as professionals, use circuit simulators often to design and check circuit diagrams. The best thing about online simulator is, you don’t have to install anything at all on your PC or laptop. All you need is a browser and a stable internet connection. Work from anywhere just by opening the online circuit simulator website and signing in to your account. Cool, huh?

Now the question is, which simulator should one use? Which one is the best simulator? Well, in one sentence, “there is NO best simulator“. It depends on your requirement and level of expertise. If you are just a beginner, then you need a basic and less complex simulator. But if you’re professional and very expert in this field, obviously you’ll need a complicated, multipurpose simulator.

Here I’ve listed top ten online simulators based on their popularity, functionality, pricing, and availability of library parts.

1. EasyEDA

easyeda online circuit simulator
EasyEDA online circuit simulator

EasyEDA is a free, zero-install, web and cloud-based EDA tool suite which integrates powerful schematic capture, mixed-mode circuit simulator and PCB layout in a cross-platform browser environment, for electronic engineers, educators, students, and hobbyists.

As EasyEDA is completely free, super easy to use, and feature-rich, it holds the first place.

 

Pros: 

  •  Huge and ever growing community
  • Parts library is quite massive
  • Very powerful simulator
  • High-quality PCB designing is possible
  • Designing circuit/PCB is free from any kind of hassle. Beginners can easily get started to EayEDA
  • EasyEDA is completely FREE

Cons:

  • Getting the simulation done is kinda difficult. You need to follow the guide.

2. circuits.io (Autodesk Circuits)

(circuits.io) Autodesk circuits online simulator
(circuits.io) Autodesk circuits online simulator

Autodesk Circuits empowers you to bring your electronics project ideas to life with free, easy to use online tools.

A circuit/PCB designing tool and simulator developed by AutoDesk, empowering you to design the circuit, see it on the breadboard , use the famous platform Arduino, simulate the circuit and eventually create the PCB. You can program the Arduino directly from this software simulation.

Pros:

  • The output design is easier to interpret and will be a handy reference while making a real life connection
  • It can simulate Arduino
  • The library has plenty of parts

Cons:

  • Designing circuit is bit tougher than other simulators
  • Can’t draw a circuit quickly

3. PartSim

PartSim online Circuit Simulator
PartSim online Circuit Simulator

PartSim is a free and easy to use circuit simulator that runs in your web browser. PartSim includes a full SPICE simulation engine, web-based schematic capture tool, and a graphical waveform viewer.

Pros:

  • This platform is pretty neat and easy to use
  • Large number of parts from vendors makes this a good choice for practical purpose
  • PartSim is entirely free to use

Cons:

  • Not so powerful simulator but ok for beginners
  • It has a lot of op-amps in library but other ICs lack

4. EveryCircuit

EveryCircuit Online Circuit Simulator
EveryCircuit Online Circuit Simulator

EveryCircuit is an online circuit simulator with a well-designed graphics. It’s really easy to use and has a great system of electronic design. It allows you to embed simulation into your web page.

Pros:

  • EveryCircuit is also available mobile platforms (Android and iOS)
  • Impressive animated representation of various dynamic parameters
  • It offers plenty of example and pre-designed circuits. Good for beginners

Cons:

  • This platform is not a free one
  • It lacks many useful ICs

5. Circuit Sims (Falstad Circuit)

Falstad Circuit Online circuit simulator
Falstad Circuit Online circuit simulator

Extremely simple web platform that runs on any browser. The platform perfectly suits beginners who want to understand the functionality of simple circuits and electronics.

Pros:

  • The simplest one. Beginners won’t have to struggle with it
  • Completely free and no account is required
  • This is an Open-Source platform

Cons:

  • The library parts are very limited
  • GUI is not attractive

6. DC/AC Virtual Lab

DC/AC Virtual Lab online circuit simulator
DC/AC Virtual Lab online circuit simulator

DC/AC Virtual Lab is an online simulator who is capable of building DC/AC circuits, you can build circuits with batteries, resistors, wires and other components.

DC/AC Virtual Lab has a pretty attractive graphics and components are real looking, but it is not in top fives because of limitation in parts library, incapability of drawing circuits and some other reasons.

Pros:

  • Simple UI, good for students and instructors
  • Parts look like real one, not just symbols

Cons:

  • DC/AC Virtual Lab is NOT completely free
  • Parts library is very much limited
  • Simulation is not that powerful

7. DoCircuits

DoCircuits online circuit simulator
DoCircuits online circuit simulator

DoCrcuits is easy to use but not much efficient. You can design both analog and digital circuits. But you have to log in to get the simulation done.

Pros:

  • Interactive design, though a bit sluggish
  • Components are real looking
  • Many readymade circuits are there

Cons:

  • You can’t use both analog and digital components on the same circuit
  • Simulation is pretty much limited
  • DoCircuits is NOT free

8. CircuitsCloud

CircuitsCloud online circuit simulator
CircuitsCloud online circuit simulator

CircuitsCloud is a free and easy-to-use simulator. It works good for both analog and digital. Beginners can easily use it but have to create an account first.

Pros:

  • CircuitsCloud is a free platform
  • Making circuit is easy here

Cons:

  • Simulation is not good. Doesn’t animate direction of current
  • Library doesn’t contain enough digital IC and MCUs

9. CIRCUIT LAB

CircuitLab online circuit simulator
CircuitLab online circuit simulator

Circuit Lab is a feature-rich online circuit simulator, but it’s not free. It’s designed with easy to use editor and accurate analog/digital circuit simulator.

Pros:

  • This platform is well-built with fairly extensive library that is suitable for both beginners and experimenters
  • Simulated graphs and output results can be exported as CSV file for further analysis
  • Designing circuits is easy and pre-designed circuits are available

Cons:

  • This is not a free platform but you can use the demo for free
  • The simulation could have been better with interactive simulations apart from the graphical representation
  • More digital ICs should be added in library

10. TinaCloud

Tina Cloud online circuit simulator
Tina Cloud online circuit simulator

TINA Design Suite is a powerful yet affordable circuit simulator and PCB design software package for analyzing, designing, and real time testing of analog, digital, HDL, MCU, and mixed electronic circuits.

TINA is a very sophisticated circuit simulator and a good choice for experienced persons. It’s not very easy for beginners and takes a while to get started. TINA is not free. But if you consider the performance, the price is negligible.

Pros:

  • This simulation program has sophisticated capabilities
  • Simulations are performed on company’s server, hence it provides an excellent accuracy and speed
  • Various types of circuits can be simulated

Cons:

  • This platform is NOT for beginners
  • Even if you are experienced one, initially you may face some difficulties
  • Tina Cloud is NOT a free simulator
Others:

So, now you have a list of “Top Ten Online Circuit Simulators”, but this isn’t a final one. There are other online simulators which you may find as good for you. simulator.io, Gecko-SIMULATIONS etc. are some of them. I recommend you to try all of them before choosing one as perfect.

If you have any other online simulator in your knowledge to share with us, please do. Any suggestion is highly appreciated.

Scalar Network Analyser

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M0xpd documented his experience building DuWayne’s Scalar Network Analyzer Jr:

DuWayne’s project uses an AD9850 in one of our familiar modules to generate RF, under the control of an Arduino NANO. You can read on DuWayne’s blog how the SNA Jr is the descendant of earlier experiments in which an Si5351 was used as the signal source.

Scalar Network Analyser – [Link]

How to Connect to a Raspberry Pi with an Ethernet Cable

circuitbasics.com show us how to connect Rasperry Pi using Ethernet cable.

If you use your Raspberry Pi as a gaming console, media server, or stand-alone computer, WiFi is a great way to get internet access. But if you connect to your Pi with SSH or a remote desktop application a lot, WiFi is actually one of the slowest and least reliable ways to do it. A direct ethernet connection is much faster and a lot more stable.

How to Connect to a Raspberry Pi with an Ethernet Cable – [Link]

LT8390 – 60V Synchronous 4-Switch Buck-Boost Controller with Spread Spectrum

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The LT8390, is a synchronous buck-boost DC/DC controller that can regulate output voltage, and input or output current from input voltages above, below and equal to the output voltage. Its 4V to 60V input voltage range and 0V to 60V output voltage range are ideal for voltage regulator, battery and supercap charger applications in automotive, industrial, telecom and even battery-powered systems. The LT8390’s 4-switch buck-boost controller, combined with 4 external N-channel MOSFETs, can deliver from 10W to over 400W of power with efficiencies up to 98%. Its buck-boost capability is ideal for applications such as automotive, where the input voltage can vary dramatically during stop/start, cold crank and load dump conditions. Transitions between buck, buck-boost and boost operating modes are seamless, offering a well regulated output even with wide variations of supply voltage. The LT8390 is offered in either a 28-lead 4mm x 5mm QFN or thermally enhanced TSSOP to provide a very compact solution footprint. [source]

LT8390 – 60V Synchronous 4-Switch Buck-Boost Controller with Spread Spectrum – [Link]

HiFive1, An Open-Source RISC-V Development Kit

By bringing the power of open-source and agile hardware design to the semiconductor industry, SiFive aims to increase the performance and efficiency of customized silicon chips with lower cost.

The Freedom E310 (FE310) is the first member of the Freedom Everywhere SoCs family, a series of customizable microcontroller SoC platforms, designed based on SiFive’s E31 CPU Coreplex CPU for microcontroller, embedded, IoT, and wearable applications. The SiFive’s E31 CPU Coreplex is a high-performance, 32-bit RV32IMAC core. Running at 320+ MHz.

FE310 Block Diagram
FE310 Block Diagram

SiFive recently announced the ‘HiFive1’, an open-source Arduino-compatible RISC-V development board that features the FE310 SoC. It is a 68 x 51 mm board consists of 19 Digital I/O pins, 9 PWM pins, and 128 Mbit Off-Chip flash memory. HiFive1 operates at 3.3V and 1.8V and is fed with 5V via USB or with 7-12V DC jack. The board can be programed using Arduino IDE or Freedom E SDK.

HiFive1’s Specifications:
  • Microcontroller: SiFive Freedom E310 (FE310)
    • CPU: SiFive E31 CPU
    • Architecture: 32-bit RV32IMAC
    • Speed: 320+ MHz
    • Performance: 1.61 DMIPs/MHz, 2.73 Coremark/MHz
    • Memory: 16 KB Instruction Cache, 16 KB Data Scratchpad
    • Other Features: Hardware Multiply/Divide, Debug Module, Flexible Clock Generation with on-chip oscillators and PLLs
  • Operating Voltage: 3.3 V and 1.8 V
  • Input Voltage: 5 V USB or 7-12 VDC Jack
  • IO Voltages: Both 3.3 V or 5 V supported
  • Digital I/O Pins: 19
  • PWM Pins: 9
  • SPI Controllers/HW CS Pins: 1/3
  • External Interrupt Pins: 19
  • External Wakeup Pins: 1
  • Flash Memory: 128 Mbit Off-Chip (ISSI SPI Flash)
  • Host Interface (microUSB): Program, Debug, and Serial Communication
  • Dimensions: 68 mm x 51 mm
  • Weight: 22 g
HiFive1 Top View
HiFive1 Top View

riscv-blog-logoRISC-V is an open source instruction set architecture (ISA) that became a standard open architecture for industry implementations under the governance of the RISC-V Foundation. The RISC-V ISA was originally designed and developed in the Computer Science Division at the University of California to support computer architecture researches and education.

In a comparison with Arduino boards, the HiFive has 10x faster CPU clock, larger Flash memory, and lower power consumption. The table below shows the difference between Arduino UNO, Arduino Zero, and Arduino 101:

Comparison

HiFive may be a helpful tool for system architects, hardware hackers and makers, to develop RISC-V applications, customize their own microcontroller, support open-source chips and open hardware. It is also good as a getting started kit to learn more about RISC-V.

You can order a HiFive board for $59 at its crowdfunding campaign, and the full documentation is available here.

The New Fujitsu ReRam

Resistive random-access memory (RRAM or ReRAM) is a type of non-volatile (NV) random-access (RAM) computer memory that works by changing the resistance across a dielectric solid-state material often referred to as a memristor.

Fujitsu Semiconductor has just launched world’s largest density 4 Mbit ReRAM product for mass production: MB85AS4MT. Partnering with Panasonic Semiconductor Solutions, this chip came to life.

The MB85AS4MT is an SPI-interface ReRAM product that operates with a wide range of power supply voltage, from 1.65V to 3.6V. It features an extremely small average current in read operations of 0.2mA at a maximum operating frequency of 5MHz.

It is optimal for battery operated wearable devices and medical devices such as hearing aids, which require high density, low power consumption electronic components.

20161029154434_mb85as4mt

Main Specifications
  • Memory Density (configuration): 4 Mbit (512K words x 8 bits)
  • Interface: Serial peripheral interface (SPI)
  • Operating power supply voltage: 1.65V – 3.6V
  • Low power consumption:
    • Read operating current: 0.2mA (at 5MHz)
    • Write operating current: 1.3mA (during write cycle time)
    • Standby current: 10µA
    • Sleep current: 2µA
  • Guaranteed write cycles: 1.2 million cycles
  • Guaranteed read cycles: Unlimited
  • Write cycle time (256 byte page): 16ms (with 100% data inversion)
  • Data retention: 10 years (up to 85°C)
  • Package: 209 mil 8-pin SOP

This figure shows the block diagram of the chip:

reram

MB85AS4MT is suitable for lots of applications like medical devices, and IoT devices such as meters and sensors. In addition, the chip has the industry’s lowest power consumption for read operations in non-volatile memory.

For more information about MB85AS4MT, you can check the datasheet and the official website.