An A/B battery replacement for the Zenith TransOceanic H-500 radio with filament regulation

pics-ZTO_H500_battery_box_inside_1a-600

KA7OEI built a battery pack to replace the obsolete “A/B” battery for Zenith TransOceanic (ZTO) H-500 and wrote a post on his blog detailing its assembly:

There are several things that I decided that this voltage converter should do:

  • Automatically power up and shut down when the radio is turned on and then off
  • Cause no interference to radio reception
  • Consume minimal current when the radio is turned off
  • Produce a regulated B+ voltage
  • Regulate the filament voltage so that the radio functions properly even when the battery is mostly discharged so that maximum use can be made of its total capacity

While I was at it I decided that it should be able to do a few other things:

  • If the radio is on for a very long time (e.g. more than about 2 hours) do a “power save” shut down to (hopefully) prevent the batteries from being completely flattened
  • “Lock out” the operation of the radio if the batteries are already extremely low.  Avoidance of completely killing the battery may reduce the possibility of their leaking

A high current power supply built around a server voltage regulator

pcb-built

Andy Brown designed and built a power supply controller board for the Artesyn NXA66:

I decided that the best way to exploit the results of the reverse engineering effort was to design a controller board that would host the NXA66 and expose its functionality via a front panel. I’d throw in a few simple extras myself such as current monitoring and data logging and finally I’d implement it as a through-hole design so that it could be implemented by people of all skill and equipment levels.
The end result will be a bench-power supply that’s cheap to build and has a current supply level greater than that of most supplies priced at hobbyist levels.

More details at Andy Brown’s blog.

Check out the video after the break. Continue reading “A high current power supply built around a server voltage regulator”

#FreePCB via Twitter to 2 random RTs

IRToy-600x369

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

DIY thermal imaging

thermal_imaging

Niklas Roy has written an article detailing his DIY thermal imaging with an IR thermometer:

I did not want to hack/destroy the brand new thermometer, as I still plan to use it in its original form later. For that reason, I decided to temporarily attach an old webcam to its back. This way, my laptop can read the temperature via the thermometer’s LCD display.
In a second step, I connected two RC servos to an Arduino. Those servos pan and tilt the thermometer – thus, the thermometer can scan an image. I also wrote a program in Processing, which sends the X and Y servo positions to the Arduino and at the same time reads the temperature via the webcam. The program draws a thermal image based on the measured temperatures.

More info at Niklas Roy’s project page.

Check out the video after the break. Continue reading “DIY thermal imaging”

Teardown, experiments and calibration of an Ist-Rees laser spectrum analyzer

pics-Teardown

Ist-Rees laser spectrum analyzer teardown from The Signal Path:

In this short episode Shahriar takes a close look at an Ist-Rees laser spectrum analyzer. This simple instrument is based on a continuously rotating diffraction mirror to detect various wavelengths. A trigger signal is used to denote the beginning of the scan and the front-panel display shows the current selected wavelength. By aligning the output signal with the trigger signal the wavelength of the input light can be measured.
After the unit teardown, the instrument is used to measure the wavelength of a semiconductor 1310nm laser. The unit is calibrated using this source and is then used to measure the infrared leakage wavelength from a green laser pointer.

Check out the video after the break. Continue reading “Teardown, experiments and calibration of an Ist-Rees laser spectrum analyzer”

Muxtronics open source 12V powerbank

powerbank-drawing

A custom 12V powerbank for Cube i7 Stylus from Muxtronics:

Why would anyone even try to build a power bank – i.e. an external battery for charging mobile devices – these days? These things are commodity, it’s impossible to compete. Right? Well, that is until you find out that the type of power bank for your application, namely charging a higher-end tablet with 12V input, does not exist cheaply. Looking around for 12V power banks yields a lot of li-ion car jumpstarters (*) and very few actual power banks. Those that exist are pretty expensive and often don’t even perform that well.

Project info at muxtronics.nl.

Check out the video after the break. Continue reading “Muxtronics open source 12V powerbank”

TI’s Little Professor

P1210107-600

A teardown of TI’s Little Professor vintage calculator from KuzyaTech:

This thing was sold for parts and repair since the seller did not think it was working. As it turned out, everything worked just fine, but not in an expected way. This is not your typical calculator, but rather a teaching one.

More details at KuzyaTech.com.

Bus Pirate v3.8 free PCB build

pics-freePCBbuild-600

Ben built a free Bus Pirate v3.8 PCB.  The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Free PCB Sunday: Pick your PCB

BP-600x373

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Testing inductors at application frequencies

an_coilcraft_doc119

An app note from Coilcraft on inductance and Q parameters which are the important factors of an inductor and how these values are found. Link here (PDF)

The accurate measurement of an inductor has always been more difficult than the measurement of other passive components. The primary difficulty with coil measurements lies in the fact that coil inductance and its efficiency are quite frequency dependent; similarly, coil parasitics (distributed capacitance and core/copper resistive losses) vary dramatically with frequency. The measurement of a coil at the application frequency, so-called “use frequency testing,” is more representative of the basic value of the component in circuit than testing at traditional standard frequencies.

Often, the value of a measurement frequency is specified for measurement convenience alone. If the measurement frequency is not the circuit (or “use”) frequency, the result of testing generally will not yield the same inductance value or display the same efficiency as seen by the intended circuit. Given that recent developments of equipment and methods now allow more flexibility in test frequency selection, inductors should be tested at the actual frequency of use, particularly if tight tolerances are required.

App note: Working voltage ratings applied to inductors

Coilcraft’s application note about why there are no voltage ratings specified on inductors. Link here (PDF)

Voltage ratings are often specified for many electronic components, including capacitors, resistors and integrated circuits, but rarely for inductors. This article addresses the reasons why working voltage ratings are not typically published for inductors.

There are challenges to determine voltage ratings for inductors, either by testing or calculation. Inductors do not support dc or low frequency working voltages unless the inductance is high (typically >1 mH). Testing to verify working voltage can be difficult and should be application dependent. The various ways inductors are made, and the stresses of processes like wire bending, make calculating a theoretical voltage rating infeasible.

This article presents these issues to make it easier to choose an inductor most appropriate for the specific application.

Free PCB coupon via Facebook to 2 random commenters

BP

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Single tube Lethal Nixie clock

singletubenix1-600

Andrew Moser made a lethal nixie tube clock:

Clock 1: Single tube Lethal Nixie clock — you know having all the high voltage lines exposed and un-insulated. Inspiration for this design was from this clock. Unfortunately I built mine right after having surgery. I think the painkillers had something to do with the aesthetics… Anyhow I wasn’t electrocuted while building it under the meds…That’s always a plus!
ATMEGA 328 arduino with a DS1307 RTC for timekeeping. Basically the arduino pulls time from the RTC then updates IO. During this it’s got a time based ISR that: interrupts the code, measures the high voltage, then makes necessary tweaks to the boost converter duty cycle via a proportional controller.

Project info at ReiBot.org.

Check out the video after the break. Continue reading “Single tube Lethal Nixie clock”

How to make a simple 1 watt audio amplifier (LM386 based)

schematic7-750x422

A tutorial on making an LM386 audio amplifier circuit from Afrotechmods:

A tutorial on how to use the popular LM386 class AB audio amplifier IC to build a simple mono 1 watt audio amplifier. It costs less than $3 in parts! There is also a brief discussion of how to use high pass filters to prevent op-amp oscillation and subsequent noise.

More info at Afrotechmods tutorial page.

Check out the video after the break. Continue reading “How to make a simple 1 watt audio amplifier (LM386 based)”

Debugging ARM Cortex-M0+ HardFaults

next-step-will-be-a-hard-fault

Erich Styger has written an article on debugging a hard fault on an ARM Cortex-M0+ device:

To me, one of the most frustrating things working with ARM Cortex-M cores are the hard fault exceptions. I have lost several hours this week debugging and tracking an instance of a hard fault on an ARM Cortex-M0+ device.

More details at MCU on Eclipse homepage.

EMP Jammer build

pics-F5I1C56IXUS8NZ4-600

A how-to on making an EMP jammer from JunezRiyaz, project instructables here:

An electromagnetic pulse (EMP), also sometimes called a transient electromagnetic disturbance, is a short burst of electromagnetic energy. Such a pulse may occur in the form of a radiated electric or magnetic field or conducted electrical current depending on the source. EMP Jammer is a device capable of generating a transient electromagnetic disturbance that radiates outward from its epicenter, disrupting electronic devices.

Check out the video after the break. Continue reading “EMP Jammer build”

SDR radio breathes life into a 75 year old Marconi CR100

 

pics-CR100projectmain1-600

Jon Hudson over at DesignSpark‎ writes:

This is a belated post of a fun project we did for RS Components. With the upcoming 80th anniversary of the founding of ‘RadioSpares’ – the original name for UK-based RS-Components, and the creation of an “Engineers’ Playground” as a feature of the 2016 Electronica event in Munich, we thought it might be fun to create an exhibit which could celebrate aspects of Radio receivers spanning that whole period. What if we were to take an ancient short wave receiver from the late nineteen thirties with its magnificent construction and rugged controls, and to replace the circuitry with a modern Software Defined Radio from SDRplay? What a great combination that would be! And so the project began.

More details at rs-online.com

LED traffic light

pimage5-resized-600

Domen Ipavec shared his DIY LED traffic light in the project log forum:

Traffic lights are all around us, and they seem simple enough but are they really? Real traffic lights can be a very complicated system because it requires sophisticated control and coordination for smooth and safe traffic.
The traffic light I made is much simpler. My sister works in a kindergarten where kids needed a simple traffic light for when they are riding their bikes on the playground.
The traffic light uses some cheap LEDs from China, a step-up converter and an Atmel attiny841 microcontroller to change the light from red to green at a programmed interval.

More info at Domen Ipavec’s blog.

Via the forum.

Check out the video after the break. Continue reading “LED traffic light”

#FreePCB via Twitter to 2 random RTs

IRToy-600x369

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.