Search found 5487 matches

by jack
Tue Jul 24, 2012 4:59 pm
Forum: Speakers
Topic: BBC auction...
Replies: 5
Views: 3642

BBC auction...

Looking the the prices for the Bush House kit auction, it seems that some of the speaker prices look a bit high for well-used second-hand kit with no guarantee...

http://www.ppauctions.com/auction.php?id=67
http://www.ppauctions.com/auction.php?id=71

What do the panel think?
by jack
Tue Jul 24, 2012 9:06 am
Forum: Valves
Topic: Mazda pp3/250
Replies: 12
Views: 7176

Yep they are exactly same as the one illustrated on National Valve Museum page. Apparently they are the early version which first appeared in 1932. Just a few years older than me then! A few years ago I was finding valves at boot sales nearly every week. Last year I found 3 and until today nothing ...
by jack
Sun Jul 22, 2012 3:39 pm
Forum: Valves
Topic: New OPT Amp...
Replies: 22
Views: 17017

Ray P wrote:Bruce's new book, with the 300B design (and others) is now available.

Ray

Indeed - ordered it yesterday... Due on the 25th July...
by jack
Thu Jul 19, 2012 3:22 pm
Forum: Assorted Stuff
Topic: Mobile phone question.
Replies: 12
Views: 5398

If they have smart phones and some data roaming capacity, they could install WhatsApp (free app) that will allow them to send text & pictures etc. to each other... I'd be a bit cautious about that. Data roaming gets very expensive very quickly. Our roaming charges within the EU are £3/mb, and £...
by jack
Thu Jul 19, 2012 2:39 pm
Forum: Assorted Stuff
Topic: Mobile phone question.
Replies: 12
Views: 5398

If they have smart phones and some data roaming capacity, they could install WhatsApp (free app) that will allow them to send text & pictures etc. to each other... FWIW my kids say that texting is VERY old-hat, and WhatsApp is what everyone uses now... I started using it a few months ago - very ...
by jack
Tue Jul 17, 2012 10:28 pm
Forum: Assorted Stuff
Topic: sneaky induction
Replies: 14
Views: 4270

Pacemakers use such tiny current this is feasible. Cochlear Implants use power with all that digital processing necessary so so far C.I.s use lots of batteries and the batteries stay on the outside. I wasn't actually joking - here's the Register's article - http://www.theregister.co.uk/2008/03/12/h...
by jack
Tue Jul 17, 2012 9:43 pm
Forum: Assorted Stuff
Topic: sneaky induction
Replies: 14
Views: 4270

shane wrote:
nickds1 wrote: "yes" - a POC has been done (not by me, and not on my stepfather!)
Is that anything like a PLOD?
No - they were in that lekky Smart Car :D

This was PHUCED :shock:

(Pacemaker Hacked Using Controlled Electromagnetic Discharge)
by jack
Tue Jul 17, 2012 7:25 pm
Forum: Assorted Stuff
Topic: sneaky induction
Replies: 14
Views: 4270

There was some work on cochlear implants using inductance fields to charge batteries inside the user's head! I believe the idea was shelved. They power pacemakers sometimes this way... My stepfather has one which also acts as a data logger of his heart activity, the data from which is downloaded ev...
by jack
Tue Jul 17, 2012 2:37 pm
Forum: Assorted Stuff
Topic: sneaky induction
Replies: 14
Views: 4270

We've got one of those Lektrik Car Parking charger points right outside the main entrance to the building I'm working in right now. It's been there about a year now. It had a lekky car attached to it once. Popular, not! A couple of years ago I worked in the West End (of London) - loads of electric ...
by jack
Tue Jul 17, 2012 2:04 pm
Forum: Assorted Stuff
Topic: sneaky induction
Replies: 14
Views: 4270

Shop stuff is varieties of RFID technologies - there are a bunch of those around, some more sophisticated than others - depends largely on the cost of the item how much complexity you want in the tag, e.g. just a resonant tag (set off alarm as you leave) or something that actually identifies itself ...
by jack
Fri Jul 13, 2012 11:29 am
Forum: Everyones Projects
Topic: Power Amp Dummy Load
Replies: 31
Views: 18080

Just saw this:

http://www.ebay.co.uk/itm/400308297455

The do 4 ohm and variable ones too...
by jack
Thu Jul 12, 2012 11:21 am
Forum: Assorted Stuff
Topic: Valve Amplifiers, 4th ed. MJ
Replies: 0
Views: 1191

Valve Amplifiers, 4th ed. MJ

Just been reading this - needs an errata (couldn't find one went I briefly looked this morning...) - I have corresponded with MJ before but didn't want to bother him unnecessarily...

My 3rd Ed. is probably the most heavily annotated book I have...

Anyone else had a look at the 4th ed....?
by jack
Thu Jul 12, 2012 11:16 am
Forum: Assorted Stuff
Topic: Nice bit of levitation
Replies: 8
Views: 3991

pre65 wrote:Amazing how clever frogs can be. :wink:
The sad thing is that when strimming the long grass by my office, I have seen bits of frogs levitate in multiple directions at the same time :(

Not sure what the answer is to that one - to strim or not to strim? that is the question...
by jack
Wed Jul 11, 2012 10:37 pm
Forum: Assorted Stuff
Topic: Nice bit of levitation
Replies: 8
Views: 3991

I believe the previous video relies on the Meissner Effect

Superconductors are great - This one is called diamagnetic levitation - it won an Ig-Nobel prize - you can do it with pretty much anything that has dipole molecules in it, e.g. water.
by jack
Wed Jul 11, 2012 10:21 pm
Forum: Assorted Stuff
Topic: A new desktop PC
Replies: 33
Views: 12934

Quadruple post there. That has to be some kind of record. That's android going insane - sorry. I'm on O2 and this evening the whole national network has gone nuts - 4 hours with no signal anywhere, then all insane! Of course, had you not posted, I could have gone back and removed them :) but now wi...