Twitter Updates for 05-08-2011

• 1am. Probably shouldn't be tracing a circuit diagram. 01:13:01, 2011-08-05
• New blog post: Bothersome circuit http://www.sci-fi-fox.com/?p=1183 03:17:34, 2011-08-05
• @darkuncle @marnanel Only if you don't get them to earn their keep while in there. in reply to darkuncle 03:36:59, 2011-08-05
• @nanayasleeps @song_in_heart True, though judges are expected to follow government policies and targets. in reply to nanayasleeps 03:39:06, 2011-08-05
• @Birchola DNA evidence has improved matters, but is not infallible. It can now be faked, for instance. Also you leave it everywhere. in reply to Birchola 03:40:37, 2011-08-05
• Hmph. Settings are all on and correct, I'm just not receiving LiveJournal notification emails anymore. 11:47:43, 2011-08-05
• @tajasel Ouch! Don't worry, there's always loan sharks or organ donation! #CashTicketsAreTooDamnExpensive in reply to tajasel 12:38:21, 2011-08-05
• There's a bad smell in here. I mean it literally. Welp, was cleaning up anyway. 13:24:09, 2011-08-05
• Suspect I must have knelt or trodden in something. Smells a bit like puke in here. :P 13:24:30, 2011-08-05
• Found the source of the smell. Forgot about a discount Cadburys Fudge Yoghurt I bought a week or two back, left in coat pocket. :P 14:36:41, 2011-08-05
• Demoulded some pads to ship. Moulds clean, but pigment everywhere on wipe-down! Whuh?? Will re-cast with lower % pigment. After lunch. 15:27:05, 2011-08-05
• @JezzKitty It's okay, you love tea even more than I do! XD in reply to JezzKitty 17:01:23, 2011-08-05
• New blog post: A piss-poor scam premise http://www.sci-fi-fox.com/?p=1185 20:35:28, 2011-08-05
• @mothdust Big tattoo! Looks good! :D Take it being more organic-lined than your icon is intentional? ;) in reply to mothdust 20:50:48, 2011-08-05
• Clearing floor and putting down carpet freshener.. 20:51:08, 2011-08-05
• @PoisonedAl Agh no, I almost used it! D: I almost never slept again! @_@ in reply to PoisonedAl 22:12:08, 2011-08-05
• Room covered in "Lily of the valley" Shake 'n' Vac. 22:23:47, 2011-08-05
• Leave that to soak in while I go have a BACON sandwich. Then I'll hoover & throw out a few T-shirts. 22:24:41, 2011-08-05
• @Moshiicake This is a problem? o_o ;P in reply to Moshiicake 23:27:08, 2011-08-05
• What is it about humans when feeling threatened over something makes them do more of whatever it is that's causing others to threaten them? 23:50:33, 2011-08-05
• Is it just blindly defending the entrenched position? Laws, faith, habits, fashions.. whatever it is, when questioned it gets turned to 11. 23:52:41, 2011-08-05
• @Moshiicake Could bind yourself maybe to bring them in? Get some tensile kevlar tape.. in reply to Moshiicake 23:55:03, 2011-08-05

Mirrored from The blog-hub for Peter "Sci" Turpin.

Bothersome circuit

Very tired and about to go to bed, but traced and ID’d most of the parts on the old treadmill motor controller board.

It drives a motor rated for 180v DC, but my measurements say it’s putting out 330v DC which would make sense for rectified UK mains. I suspect on looking at the board that for UK use they dial the speed control trim-pot down to half so the PWM signal never goes above 50%.

Still means the motor’s running at twice the voltage it should though, which’d explain the overheating issues.

I don’t understand the circuit fully though. For one thing there’s a half-bridge rectifier essentially bridging the motor terminals. Surely that’d mean it’s perpetually shorted out? I don’t understand it, but suspect it might be something for dealing with back-EMF from the motor.

I also don’t understand how the MOSFET’s driving it. It all seems to be coming through a 5Watt resistor and some very thin traces, especially since the motor’s 2-2.5HP (1400Watt+). Maybe it’s because it’s late, maybe I’m just not seeing it and it’s just the trigger. Just can’t see it right now. But the circuit does work (even if the fuses and current breaker don’t. If something shorts it ALLWAYS knocks out the 30Amp breaker for the workshop).

It’s a single-sided PCB. Here’s my notes on it. A few figures are missing, but all components are marked.

I’m planning on making a much simpler control circuit, but it does involve a very large 220-110v transformer to get the proper 180v DC.

It’s been a good day. Castings done, experiments done, oscilloscope usable again, found artial pressure cooker for new vacuum degass chamber, some clearing up done.

Mirrored from The blog-hub for Peter "Sci" Turpin.

A piss-poor scam premise

Just had a phonecall from “BT tech support”. Apparently there’s “corrupted temporary files on my computer”.

 

Them: Hello, am I speaking to Mr Turpin?

Me: Yes you are.

Them: Hello, my name is Chester, I’m calling from BT tecnical support about your phone and broadband service. We’ve been monitoring that there’s corrupted temporary files on your computer..

Me: Wait, so you’re intercepting my communications..?

“Chester”: Yes sir, we..

Me: You’re SPYING on my communications??

Chester: Well sir we’re from the research depar..

Me: The only way you could know there’s corrupted files on my computer is if you’re illegally monitoring my communications!!!

Chester: Ah, well sir..

Me: What did you say your name was?

Chester: Ah? Mr Turpin.

Me: No that’s MY NAME! Fuck off please!! *I hang up*

 

Just sayin’, a good scam probably isn’t one that starts by telling you they’ve done something illegal to you.

Mirrored from The blog-hub for Peter "Sci" Turpin.