Halogen floodlight SMT reflow


David Sanz Kirbis built his own reflow device with an halogen floodlight, that is available on Github:

First test was to check the speed of the temperature rise inside a standard halogen floodlight. Reflow soldering temperature curves are quite demanding, and some adapted ovens can’t reach the degrees-per-second speed of the ramp-up stages of these curves.
I bought the spotlight, put an aluminium sheet covering the inside surface of the protective glass (to reduce heat loss), and measured the temperature rise with a multimeter’s thermometer…. and wow! More than 5ºC/s… and I better turned the thing off after reaching 300ºC and still rising quickly.
So the floodlight was able to fulfill the needs.
Next step was a temperature controller, that is, the device that keeps the temperature as in a specified reflow curve profile in each moment.

See the full post and more details on his blog, TheRandomLab.

Check out the video after the break.

Pulsecounting and deepsleep based IoT water meter


Tisham Dhar has written an article detailing his pulsecounting and deepsleep based IoT water meter project:

I admit to being a tiny bit obsessed with monitoring utility bills and gathering data on my usage patterns blow-by-blow. The energy monitoring has reduced my electricity bills, so I wanted to have a go at the water usage. Granted a lot of the water bill is fixed supply costs and sewerage charges which I can’t do much about.
A while ago I made some pulse counting breakouts with the DS1682+ RTC. I have finally got a chance to put them to good use interfacing with my mechanical water meter. The water meter has a spinning permanent magnet and in principle this can trigger a reed switch and generate pulses for accumulation by the RTC.

More details at Tisham Dhar’s blog.

Analog Discovery USB isolation



Bob writes:

Back when I was deverloping the PSU burner, I wanted to have the Analog Discovery isolated from the common ground, to avoid noise and other issues. Since I did not have a way to do this, I ended up using a laptop on battery for measurements. But for long term, I needed to have this isolation. Unfortunately, things that can isolate USB at 480Mbps or faster are too expensive to justify.
The solution
The ADUM3160 isolator can provide a magnetically isolated 12 Mbps connection, which proved to be good enough. I grabbed one ready made isolator module from ebay for about $12, cheap enough. Well, it is not perfect: the B0505S DC/DC converter provided can only supply 1W and the Analog Discovery is a hungry beast.

More info at Electrobob.com.

Hacking the DPS5005


Johan Kanflo’s OpenDPS project, a free firmware replacement for the DPS5005:

This write up of the OpenDPS project is divided into three parts. Part one (this one) covers reverse engineering the stock firmware and could be of interest for those looking at reverse engineering STM32 devices in general. Part two covers the design of OpenDPS, the name given to the open DPS5005 firmware. Part three covers the upgrade process of stock DPS:es and connecting these to the world. If you only want to upgrade your DPS you may skip directly to part three.

More details at Johan Kanflo’s blog.

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


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

LiPo batteries hacking and refurbishing


Karman wrote an article showing how to refurbish dead batteries to extend its life:

One of the difficult parts when prototyping is to find reliable power sources. Today is still hard to find the battery size we want to use because country exporting frontiers stops these chemical packages. Here I’ll show how to refurbish dead batteries by combining cells and protection circuits to preserve battery life.
An (almost) dead Apple MacBook Pro (17″) battery fell in my hands so I decided to tear it down to see if there was something profitable. Inside I found that the battery pack was composed with 6 individual cells, paired in 3 groups.

More details at Karman’s blog.

A simple push-pull audio amplifier using russian rod tubes and power transformers


KA7OEI blogged about a simple push-pull audio amplifier using russian rod tubes and power transformers:

Many years ago I’d read about the type of tube that is now often referred to as a “Gammatron” – a “gridless” amplifier tube of the 1920s, so-designed to get around patents that included what would seem to be fundamental aspects of any tube such as the control grid.  Instead of a grid, the “third” control element was located near the “cathode” and “anode”.  As you might expect, the effective gain of this type of tube was rather low, but it did work, even though it really didn’t catch on.  It was the similarity between the description of the “Gammatron” and these “rod” tubes that intrigued me.

More details at KA7OEI’s blog.

Hacking your mouse for rapid firing


Kerry Wong has written an article detailing a simple hardware hack to make your mouse capable of doing rapid firing:

In this blog post, I will show you a simple hardware hack to make your mouse capable of rapid firing (or automatic continuous clicking). Of course you can always resort to software mods to achieve the same goal, but admittedly doing so in hardware is nevertheless more fun and as a bonus you also get an extra button. A video demonstrating this hack can be found towards the end.
For a typical mouse, whenever a button is clicked the output voltage level from the button changes between high (e.g. Vcc) and low (e.g. Ground) and this voltage level is in turn translated into the clicks. So the idea behind this hack is simple, if we could connect a circuit in parallel to the mouse button and automatically change the output voltage level we would essentially achieve the same effect as physically clicking the button.

More details at Kerry Wong’s blog.

Check out the video after the break.

Nuclear physic applied in smoke detectors


Robert Gawron writes:

Not many people know, but in some smoke detectors, radioactive materials play an essential role. Today I will present one of those devices, and my -successful- attempt to reverse engineer it and get the circuit diagram.
Those smoke detectors uses a small amount of Americium-241 (chemical symbol: Am) obtained in nuclear reactors as a decay product of Plutonium-241. Am241 emits mainly alpha particles, but also some gamma rays. In smoke detectors it is in a form of an oxide Am02.

More details at Robert Gawron’s blog.