Tag Archives: Hacks

Analog Discovery USB isolation

via Dangerous Prototypes



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

via Dangerous Prototypes


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

via Dangerous Prototypes


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

via Dangerous Prototypes


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

via Dangerous Prototypes


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.