AU ordinary power plug, plug packs and extension cord sockets

Electrical items personally imported to Australia (eg eBay purchases) commonly do not comply with some basic mandated safety features that can be checked with a cursory visual examination.

10A Extension cord sets (AS/NZS 3120)

 

Extension cord sets sold in Australia for more than a decade must have two ‘new’ features as in the pic above:

  • insulated live pins (active and neutral); and
  • shrouded socket;

Plug tops at less than 20A (AS/NZS 3112:2011)

Plug tops at less than 20A must have insulated live pins (active and neutral), and the earth pin if fitted should be longer to make contact first. Continue reading AU ordinary power plug, plug packs and extension cord sockets

Arduino 1.6.12 – adding Optiboard boards.txt

Optiboot is the default bootloader for Arduino Uno, and I use it other Arduinos (eg Nano) for all the good reasons Arduino put it on Uno.

To make that work conveniently, I append the Optiboot boards.txt file to the Arduino distribution.

Above is a screen dump of the options added by the appended file. Continue reading Arduino 1.6.12 – adding Optiboard boards.txt

BLHeli Hobbywing XRotor 40A (MkII) vs SimonK Hobbyking 9261000003 40A

This article documents a comparative test of a Hobbywing X-Rotor 40A with BLHeli firmware and a Hobbyking 9261000003 40A with SimonK firmware.

The motor is an inexpensive BC3530-14 1100kV motor loaded with a 11×4.7″ slowfly Gemfan propeller, power input to the drive is a little over 300W at wide open throttle.

Battery is 3S fully charged.

Tests were conducted with a script that I use consistently with asrg and eLogger to capture current and rpm, and all tests conducted at similar pressure, temperature and humidity, altitude is 700m.

BLHeli configuration

The X-Rotor 40A is configured with BLHeli v14.8 MULTI, default BLHeli config, then a throttle cal for 1030/2000 performed.

SimonK configuration

The Hobbyking 9261000003 40A is flashed with SimonK’s tgy Hobbyking 9261000003 40A (1e4c01782eff85da3971f628a3bd599b7a0725eb) 15/10/2015.

FET dead times are set rather high at 2000s to be compatible with the slower F40-A. Previous tests have indicated that 1200µs dead time for high and low FETs suits the 9261000003.

Test results

Above, the test run of Hobbywing X-Rotor 40A with BLHeli v14.8 firmware. Continue reading BLHeli Hobbywing XRotor 40A (MkII) vs SimonK Hobbyking 9261000003 40A

BLHeli 14.8 damped light and active freewheeling

Aficionados of BLHeli call out the benefits of “damped light” and “active freewheeling”, terms coined by BLHeli’s author.

Since these are terms invented by BLHeli, so you might wonder whether they are truly innovative or just marketing hype for existing techniques.

Lets go to the BLHeli manual for an explanation.

Pwm damped light mode adds loss to the motor for faster retardation. Damped light mode always uses high pwm frequency. In damped light mode, two motor terminals are shorted when pwm is off

Taking the last statement first, in fact, what happens that as that during the OFF phase of the PWM drive, the high side FETs at both ends of the winding are turned ON. One FET is on for the whole phase, and the other one switches on a short time after its corresponding low side FET turns off. The short time is to allow the low side FET to cease conducting, otherwise both high and low side FETs would conduct at the same time, a current from battery +ve to -ve via the two FETs. There is a corresponding pause at the end of the PWM phase. The time delays allowed depend on the driver circuitry and FET performance, they are specified in the firmware  for a specific and don’t necessarily apply to a pin compatible ESC.

This technique is known in the wider community as COMPLEMENTARY PWM, a very standard technique. Continue reading BLHeli 14.8 damped light and active freewheeling

Hobbywing XRotor 40A (MkII)

Above is the Hobbywing (HW) X-Rotor 40A (BECless) purchased from Hobbyking. It lacks the authenticity markings promoted by Hobbywing, is it a clone? Who knows, it is Chinese.

The X-Rotor 40A was tested in its default configuration, there was no reason to change commutation timing.

Hobbywing enjoys a reputation as a quality product, a cut above the no-name products but his ESC was purchased for about A$16 + shipping, which is really a budget price for a 6S 40-60A BECless (or OPTO) ESC.

Tests were conducted with a script that I use consistently with asrg and eLogger to capture current and rpm, and all tests conducted at similar pressure, temperature and humidity, altitude is 700m.

BLHeli configuration

 

Above is a X-Rotor 40A modified with a permanent C2 interface cable for programming the MCU. The cable has a JST-SH1.0 connector (purchased as HK 258000026) to plug into the after market Tool Stick clone (HK 289000003). The wires from the left are orange, NC, brown and red. (Orange, Red and Brown wires correspond to Black White and Red dots on BLHeli documentation.) A small dot of hot melt adhesive is applied after soldering the wires to the PCB pads, and the cable folded down into the adhesive (to prevent fatigue and breakage of wires). The whole thing will be served over by clear heat shrink.
Continue reading Hobbywing XRotor 40A (MkII)

Arduino 1.6.12 & 1.6.13 AVRDUDE issues

Arduino 1.6.12 has several AVRDUDE related issues.

It comes packaged with AVRDUDE which in my installation is located at C:\Users\owen\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino6\bin\avrdude.exe . This reports itself as “Version 6.3, compiled on Sep 12 2016 at 17:24:16”.

Also relevant is the avrdude.conf file (C:\Users\owen\AppData\Local\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino6\etc\avrdude.conf).

This article relates to failures to program a bootloader, and failures to program the application using the very common USBASP.

There were two obvious problems:

  1. a false warning message about setting SCK rate, and fatal failure to contact the target; and (when that is resolved)
  2. failure to verify efuse=0x05.

Continue reading Arduino 1.6.12 & 1.6.13 AVRDUDE issues

Robust programming of Silabs based BLHeli ESCs

This article describes a solution for robust and reliable ‘production’ programming of Silabs based BLHeli ESCs.

The intention is to test and tune the BLHeli configuration, save the configuration in some form, and a scripted solution to programming multiple ESCs now and later replacements with high confidence that they are exactly matching configurations.

There does not appear to be any batch facility for writing flash using the BLHeli bootloader, nor does it appear that BLHeliSuite can save the relevant hex files for later use, so excluding use of the BLHeli bootloader.

The configuration data is held in a block of flash memory labelled EEPROM in the source code. It is not actually EEPROM, the MCU does not have EEPROM, but for consistency the block will be referred to as EEPROM in this article.

Having tested and tuned the configuration using BLHeliSuite, the EEPROM block from the test ESC is read back using Silabs Flash Programming Utility (FPU) and a toolstick attached to the ESC’s C2 interface.

Above, reading the EEPROM block.

The EEPROM block is them merged over the distribution hex file to create a custom hex file for repeated use. Continue reading Robust programming of Silabs based BLHeli ESCs

Another RFI mod of a speaker mic (41-80K) for DMR use

I bought a remote speaker-microphone (RSM) for a MD-390 DMR portable from 409shop.com, a 41-80K.

They assured me it was compatible with the radio in digital mode, but it turned out to be lousy with ‘motorboat noise’ on tx audio due to RF ingress tot he electret capsule.

Since the RSM was otherwise a good rugged and economical product, it was worth trying to rectify the RF ingress problem.

Above is a pic of the electret. Two fine tracks can be seen bonding the metal can of the electret to the -ve pin, so that is good… the can showed low resistance to the -ve pin. The +ve line is bypassed to the -ve line about 12mm from the electret with an unknown capacitor, but it was clearly not effective at 440MHz. Continue reading Another RFI mod of a speaker mic (41-80K) for DMR use

Ten-tec on the meaning of SWR

In a recent long running thread on impedance matching on one of the online fora, one poster offered the Ten-tec 540 manual as a reference for clarity on the subject (which of course got murkier with every posting as contributors added their version to the discussion).

The Ten-tec 540 was made in the late 1970s, one of the early radios with a solid state PA, and their manual give the Technical facts of life to guide new owners to successful exploitation of this new technology.

Amongst the technical facts of life is this little gem:

The standing wave ratio is a direct measure of the ratio between two impedances, ie an SWR of 3 to 1 tells us that one impedance is three times the other. Therefore the unknown impedance can be three times as large or three times as small as the known one. If the desired impedance that the transceiver wants to see is 50 ohms, and SWR of 3 to 1 on the line may mean a load impedance of either 150 or 17 ohms. …

This says that the SWR wrt 50Ω implies just two possible impedances, he is very wrong… it implies an infinite set of possible impedances. Continue reading Ten-tec on the meaning of SWR

Retevis MD-380 speaker mic modification to reduce RF interference

Remote speaker-microphones and DMR portables discussed RF ingress to Speaker Mics(RSM) used with DMR radios in digital mode.

The problem

I purchased a Retevis SM that was advertised as original equipment for the MD-380, but turned out to be lousy with RF interference in the form of the ‘motorboat noise’ on transmit audio.

Dismantling the SM (fighting the way through TORX with PIN screws, what are they trying to protect) I found there is precious little RF filtering, just a single SMD cap at the end of a long (wrt 500MHz) branch track.

A solution

Above is the modified SM. Continue reading Retevis MD-380 speaker mic modification to reduce RF interference