Search found 1650 matches

by ahull
Mon Dec 11, 2017 12:17 pm
Forum: General discussion
Topic: AC Dimmer
Replies: 39
Views: 280

Re: AC Dimmer

It is no more dangerous than that high power resistor. Neither has galvanic isolation.
by ahull
Mon Dec 11, 2017 11:41 am
Forum: General discussion
Topic: AC Dimmer
Replies: 39
Views: 280

Re: AC Dimmer

... Also... The circuit is really wasteful, as it uses high wattage resistors to drop the mains voltage to the 2 or 3 v needed to light the LED in the opto coupler. Half watt resistors will get hot as they will need to dissipate around 0.96W i.e 96% of their maximum rated value ... It occurs to me,...
by ahull
Mon Dec 11, 2017 10:35 am
Forum: General discussion
Topic: AC Dimmer
Replies: 39
Views: 280

Re: AC Dimmer

The issue is that you need to actually synchronise the dimming with the zero crossing point of the mains, and this needs to be detected. You cannot estimate it, as the mains frequency is not 100% accurate (and neither is the timer on the STM32F103), so there will always be some discrepancy between t...
by ahull
Mon Dec 11, 2017 10:08 am
Forum: General discussion
Topic: AC Dimmer
Replies: 39
Views: 280

Re: AC Dimmer

If you mean a timer running at the mains frequency, then no. Your timer would not be synchronised to the exact frequency of the mains and this would result in unpredictable results, I imagine your light or other load would pulse at a frequency equivalent to the difference between your timers approxi...
by ahull
Sun Dec 10, 2017 7:20 am
Forum: Ideas & suggestions
Topic: How to evaluate digitalWrite at compile time?
Replies: 8
Views: 754

Re: How to evaluate digitalWrite at compile time?

dannyf wrote:
Sat Dec 09, 2017 6:55 pm
...
trying to do what you are trying to do is like driving a pig through a square hole.
That can work... if you choose the correct pig.

Image

;)
by ahull
Fri Dec 08, 2017 11:38 am
Forum: STM32F103 Boards
Topic: Blue Pill crystal does not start
Replies: 13
Views: 450

Re: Blue Pill crystal does not start

It sounds to me like you are setting the wrong clock source for the RTC (or the wrong source is set by some other code within the libs you are using), when entering your sleep mode. You need to ensure the 37768 Hz crystal remains the clock source for the RTC, otherwise you may end up loosing accurac...
by ahull
Fri Dec 08, 2017 9:38 am
Forum: Off topic
Topic: Linux Journal
Replies: 33
Views: 441

Re: Linux Journal

For me Microsoft is far from ideal too, being the big corporation and the shit that comes with that, but it feels like a better managed & more usable environment for me :). I think you should crank up a modern distro, Linux Mint or Ubuntu for example, and see how much things have changed. You shoul...
by ahull
Thu Dec 07, 2017 8:58 am
Forum: Off topic
Topic: am i the only one ?
Replies: 9
Views: 152

Re: am i the only one ?

@ahull i was trying to start the second half of my pedal the coastline, in 2012 i think. 2011 was st annes to st annes via both newports, shell island, lands end, dover and hull. stayed for a week, 100yds to beach, mussels galore - on rocks not ropes:-) £7 a night. the southern newport, the time to...
by ahull
Thu Dec 07, 2017 8:28 am
Forum: Off topic
Topic: Linux Journal
Replies: 33
Views: 441

Re: Linux Journal

I've never been a big fan of all things Micro$oft, however, they do seem to have a tenacious grip on the majority of people's perception of what can be done with their computer. Most of us don't like to stray out of our comfort zone. Having said that, if you give someone Linux, but don't tell them w...
by ahull
Wed Dec 06, 2017 9:57 am
Forum: Off topic
Topic: am i the only one ?
Replies: 9
Views: 152

Re: am i the only one ?

"...diary entries she said she had wrote at the time ..." certainly does not qualify as "standard English". It is grammatically incorrect, and would have had "Granny Bell" my English teacher pulling her hair out. :D Interestingly some of these idioms are in common usage in parts of the country. It w...