Curtis 1231c diodes: Diotec DR7506FR vs TSR2402R

I am looking to replace the MOSFETS, diodes, and capacitors in my Curtis 1231c with upgraded components. I unsoldered one of the existing TSR2402R (7103 K) diodes from the power board and tested it with my Fluke meter and bench power supply.

Here are my results:
Power Supply providing 3.2A, forward voltage drop: 0.776 volts
Power Supply providing 2.0A, forward voltage drop: 0.737 volts
Power Supply providing 1.0A, forward voltage drop: 0.697 volts
Fluke Diode Setting: 0.351 vdc

Average time for the button temperature to raise from 25 °C to 50 °C with a 3.2A current: 45 seconds

The replacement parts I purchased were from DIOTEC, specifically their DR7506FR model (the R at the end means “Reverse Polarity”, making them an exact drop in replacement in form factor and polarity). They were marked: “DT110  DR7506FR” plus a diode schematic. Here are my results for the upgraded component:

Power Supply providing 3.2A, forward voltage drop: 0.754 volts
Power Supply providing 2.0A, forward voltage drop: 0.700 volts
Power Supply providing 1.0A, forward voltage drop: 0.646 volts
Fluke Diode Setting: 0.399 vdc

Average time for the button temperature to raise from 25 °C to 50°C with a 3.2A current: 47.5 seconds

Of course, the original diode I’m measuring had been in use for many years (I estimate ~750 hours of driving time given the 22K miles) and was heated up as part of the soldering and unsoldering process, while the DR7506FR I tested was brand new straight from the manufacturer. After I unsolder a few more diodes I’ll check them to make sure their readings are similar. (I’ll probably also test a few other DR7506FR diodes from the bag as well.)

Of all the measurements, the temperature rise time measurement was the least scientific, as I was using an inexpensive non-contact IR thermometer and attempting to point it at a small button in each diode, waving it back and forth to find the hottest temperature. I took 4 measurements on each diode (alternating to let the other one cool down) and averaged them together. In general, the readings from the DR7506FR were longer than from the original TSR2402R with one exception. If I throw out that pair of readings, the averages would be 46 seconds vs 50 seconds. Given that the measured forward voltage drop for the DR7506FR was lower for any real amperage readings, it dissipating less power and taking longer to rise to 50 °C appears to be reasonable.

T-Mobile DIGITS (android) app review

T-Mobile is offering a beta program where you can sign up for “Virtual” phone numbers, and/or use one number on multiple devices.

Basically, it’s a VOIP service that allows you to have one main (sim card) number on a device, plus one or more “virtual lines”, and then use their VOIP application (called DIGITS) to log into your account on any device and make/receive calls and send/receive SMS/MMS messages.

By default it allows you to “use minutes” to call in or out on your “virtual lines” which means that it redirects voice traffic over your regular phone number so you can use it even if your data service isn’t the best, (which would solve the “bad quality” VOIP issues I’ve seen with Freedompop), and it always sends messages via data. But, you can tell it to “use data” for voice calls, and go full VOIP (for example, on a wifi only device).

A select few Samsung phones have software built in that handles the virtual lines and VOIP calling, but for all other phones, you have to install the T-Mobile DIGITS application.

The concept is good, and the service works as it is supposed to, but the DIGITS application itself (at least as I tested it on a Nexus 6) has a few issues.

The first issue is that it burns through data like it’s streaming video. I’d accuse them of ex-filtrating data off my phone, except I don’t have anything valuable enough for t-mobile to try and steal. I suspect the application just has a bug somewhere that makes it check in with servers much, MUCH more frequently than it should.

For example, when using the service for a few days away from wifi, I racked up 320 MB of data, while IDLE. (T-mobile gave me extra data when I called to report this behavior, but I can see why it’s still in BETA).

Also, it refuses to work unless you have location services enabled. I guess this could be an enhanced 911 liability issue where they want to be sure to be able to give an accurate address to police if you call 911, but I already had to enter in my E911 home address just to activate the application. It seems like they could ask for permission to turn on location services if needed, and then NOT turn them on unless you called 911, as this drains the battery.

In addition to powering up your GPS all the time, the application itself uses a lot of battery power when idle in the background. (note, the graph below is just the application usage, and does not include the extra power sent to the GPS chipset to be always active…)

When you are using more data and more power than the Google App while sitting in the background idle, you know your app needs to go on a diet.

In summary, multiple virtual lines is an interesting and useful concept, but until the DIGITS app doesn’t kill your battery life and suck down your bandwidth when idle, I think a dual sim phone is a better solution for two phone lines.

Curtis 1231c Replacement Power board components

My Curtis 1231C motor controller blew up some MOSFETs and died. I replaced it with a used unit to get my truck back on the road, but now I’m interested in repairing the one that died so that I’ll have a spare.

I might be able to replace the components that died with exact replacement parts (but the IXTH50N20 MOSFETs are hard to find nowadays, and the diodes are basically unobtainable) to get it working, but since I have it open and am doing all of this work, I am exploring alternative (new) components that will have higher ratings and possibly give my controller more capacity or at least more resistance to blowing up again.

Of course, if I replace one component (power switching MOSFET, freewheeling diode, or ripple controlling capacitors), I will probably need to upgrade the other two as well so that I don’t just move the weak link from the MOSFETS to the capacitors or diodes.

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Curtis 1231C-8601 500A PWM DC Motor Controller teardown

After replacing the Curtis 1231C-8601 motor controller that had failed, I opened the case up to figure out what had failed.  The controller hardware is inside of an aluminum extrusion with both ends “potted” with some black semi-flexible material (hard silicon perhaps?) that could be cut using a razor knife and a lot of effort.

Inside, there is a Pi shaped piece of aluminum extrusion that acts as the heatsink for the MOSFETS and freewheeling diodes, as well as being electrically connected to the motor – terminal. It is held against a large thermally conductive, but electrically insulating pad, which separates it from the controller case, but allows heat to be dissipated. It is held in place with 8 screws that pass through insulating plastic brackets into the bottom of the case.

People online had told me that these screw holes were “potted”, but on my controller they were just filled with two rubber plugs.They also told me that you could not cut through the Curtis potting material with a razor knife. [This super hard potting material was also prone to cracking at the edges and letting moisture into the controller, so a flexible rubber like material is better anyways…]

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YouTube copyright Claim by AdRev for Rights Holder – Flight of the Bumblebee

I posted a video on YouTube and used “Flight of the Bumblebee” as background music, which was performed by the US Army Band. Works by the government (funded by taxpayer dollars) are automatically placed in the public domain. I downloaded it from at this link:

A day after uploading it, I received a notice from YouTube that said:

“Copyrighted music was found in your video. Don’t worry–you can still make money from it, but some of the revenue will be shared with the copyright owner.”

The claim info listed:
Copyrighted song: EPM019_037_Flight Of The Bumblebee – Boost – Ear Parade
Claimed by: AdRev for Rights Holder”

It is understandable that YouTube’s content ID system may accidentally confuse one public domain recording of Flight of the Bumblebee with another, but it does make more work for me (I have to dispute the claim) and presumably more work for “AdRev for Rights Holder” (assuming they actually review my dispute).



Two days later I received an email from YouTube:

Hi Jay Summet,

Good news! After reviewing your dispute, AdRev for Rights Holder has decided to release their copyright claim on your YouTube video.

Video title:

If you earned any money during the dispute, you should receive that money as part of your next YouTube payment.

– The YouTube Team”

YouTube copyright Claim by Believe Music song 0604

I used a music track that I downloaded from an account on SoundCloud that was giving away their music royalty free for one of my videos. Unfortunately, a few hours after posting the video on YouTube, I received a copyright claim via YouTube from “Believe Music”, which claimed that I was using their song “0604” on the video and requesting to split any ad revenue with them (The video was not monetized).

I submitted a dispute via YouTube, and 30 days later received a notice from YouTube stating that:
“Good news! Your dispute wasn’t reviewed within 30 days, so the copyright claim on your YouTube video has now been released. ”

The fact that the song was only numbered (0604) and not named in the claim, plus the fact that they never reviewed the dispute leads me to believe that Believe Music may just be trolling for revenue sharing with generic music that they are bulk submitting to YouTube.

I hope that YouTube keeps an eye on the percentage of claims that are disputed and keeps the music companies using their copyright ID system in line.

Installing an Encrypted Partition with LVM dual boot on Ubuntu 16.04

The Ubuntu 16.04 installer has the option to install full disk encryption using LVM if you are erasing everything on the hard drive. However, if you want to dual boot (use some of the hard drive for Windows, and the rest for Linux) the automated installer won’t allow you to automagically use full disk encryption.

You can still make it work, but have to do a lot of manual work using a terminal from the Live CD environment.  Here is a log of what I had to do to get it working for me.

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Build a workbench from plywood and 2×4’s


This is the workbench I build from twenty-two 2×4’s and three sheets of plywood. Because my current garage has tall ceilings, it has a lofted storage shelf. And it also has a shelf for tool and box storage below.

I used two sheets of 3/4″ builder grade plywood for the lower and upper storage shelves and a 1/2″ sheet of sanded ply for the main workbench. The dimensions were carefully chosen so that all of the excess can be used for reinforcing sheathing.

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