A sensorless brushless DC motor senses motor position for the purpose of commutation timing by using the voltage induced in the unused winding at the time. Reliably sensing the motor position for a range of motor constructions and speeds proves a challenge.
Continue reading Some thoughts on zero crossing detection in sensorless brushless DC motors
COMP_PWM is an option on SimonK ESC firmware for sensorless brushless DC motors,
Above is a capture of the waveform during two commutation steps where this FET is low side modulated. You can see that when the low side FET turns off, voltage rapidly rises to just above battery as the energy stored in the winding inductance drives current through the high side FET body diode (which drops 0.7+V) and the other high side FET that is on.
In an attempt to fix up a government orchestrated flawed regulatory and market environment that saw the dominant carrier digging its heels in to regain the right to install infrastructure that it was not required to share with competitors (ie, to allow it to reestablish a monopoly), the Labour government called for tenders from organisations to provide a National Broadband Network on its terms.
No contracts were awarded, government decided the way forward was for it to own the access network, at least for the interim, and so return to the situation that existed prior to the partial privatisation of Telstra in 1997.
Continue reading Australia’s NBN debacle limps on under a new government and new CEO
This article describes measurement of an Icom IC-7000 current consumption during SSB telephony transmission.
The capture is of an IC7000 running 100W PEP with compression off. I have read copy as loudly and consistently as I could with barely a breath, so it is an overestimate of current consumption. There was small ALC deflection, but not so much as to effectively provide compression. Compression will draw higher current, depending on the level of compression. Note too, that like many Icom radios, the IC7000 draws a relatively high current key down with no audio (4.5A here).
With the forced end of the VK1OD.net website, some builders of the Roger Beep kit may be without documentation.
I purchased an Atten 191 soldering iron thermometer which uses K thermocouple elements from Allendale UK.
With the closure of VK1OD.net as a consequence of an enforced change of call sign, a monument to the growing emphasis on train spotting in ham radio, owenduffy.net is being reorganised.
It will essentially be a blog site with a mainly electronics focus, but less ham radio focussed than was vk1od.net.
Articles will be shorter, and expose less proof / derivation / evidence to better meet the needs of modern people who I am told just don’t have time for all that stuff.
Some meatier topics will appear as a series of bite size articles to better fit the concentration span of modern readers.
Nevertheless, there will be some citations, but I will keep them to a minimum.
Excuse the large extent of self citation. It is not done for self promotion, but to acknowledge that some material is based on earlier work, some of which may be offline… and to remind me of where to look if I need to follow-up comments on the article.