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Saturday, 3 August 2013

Native Android VPN to a Cisco Router

Getting IPSec VPN connectivity between two devices is always a painful experience, somewhat akin to a root canal. So I eventually roused up the courage and decided to try and get Android 4.x native VPN  to connect to a Cisco 877 at home. A few four-letter words and some blasphemy later, I finally had success!

The below example should help anyone else having problems getting this working.

Topology
The topology is drawn below. Its very simple, consisting of:
  • A Cisco 877 running 12.4(24)T1 (advanced IP services), attached to an ADSL line on the public side, with a LAN in RFC1918 space internally. A simple NAT configuration is configured between public and private.
  • An Android phone (in my case a galaxy S3 running 4.1.2 stock) with a 3G SIM. My carrier runs CG-NAT yet the setup still works.


Thursday, 12 July 2012

3G mobile sim cards in France

Having recently spent some time in France, one of the first things I did was attempt to acquire a 3G data SIM for my phone. Having a local sim makes it really easy to get around using various smartphone apps (eg maps, train timetables and general internet goodness).

After a fair bit of research, I realised that there are no official mobile carrier outlets in the airport. So there is no easy option. Buy you can get a limited access sim from a newsagent..

I got to Charles de Gaulle airport in Paris, and discovered that the SIMs can be purchased at the "Relay" newsagent stores there. I got mine from the outlet in the car rental hall. There is also an outlet near the arrivals gate at 2D, though I don't know if they also have SIM cards.

Friday, 27 April 2012

Bluetooth receiver hack

After installing an AUX input to the radio of my Mini a while back, I got sick of continuously having to plug my phone into the cable I wired up, and needed to go wireless.

Bluetooth A2DP receivers allow a phone to send music-quality audio to a receiver device, and this is the way I wanted to go. But for a while, they were just too expensive - around $50 for a receiver, so I put it off...

Until I discovered this cheap module on DealExtreme. At only $14, it's hard to go wrong!

Wednesday, 25 April 2012

Quick drill bit holder

My drill bits come without any holder, just the usual blister pack. So using some scrap aluminium channel and a block of pine, I made something to hold them in (click for larger):


Beats picking through a mixed pile of bits...

Thursday, 15 December 2011

New Tesla parts

Found a new pair of neon sign transformers off Ebay the other day.

Advertised as a 7.5kv/30mA transformer, details in the auction revealed that there were two 7.5-0-7.5 30mA transformers, for a total of 15kV@60mA.
Manufactured only 6 years ago, and for $100 shipped, this was quite a find!

A doubling of my Tesla coil's power is imminent...

Monday, 24 October 2011

My 40kV Uncle Fester impression

With my SIDAC driver and a light bulb, I thought I'd try my hand at doing an Uncle Fester impression. Remember him from the Addams Family?

I'm putting about 40kV out of the ignition coil, enough to spark around the globe. What might not be so obvious is the little ground wire hanging off the globe's base. I'm not actually conducting the electricity myself!

Needless to say, this was done with a full understanding of the dangers of HV and the particulars of this setup.


Plenty of ozone going around, I have to hold my breath for most of it. At some stage I'll actually get a better set of photos, but the vid will do for now. :)


Tuesday, 18 October 2011

Transformer heaven

Not far from where I live is a large metal scrapyard. They have a section where motors and transformers go to die, and a lot of what they get is from the local utility + military. Military and utility transformers are highly prized for Tesla coils and other HV experiments, so I really wanted in. My TC really could do with a decent upgrade!

A friendly chat to the workers eventually led me to the owner. This place has a reputation for allowing access to artists (sparks count as "art", surely), so it didn't take long. Access granted! All the blokes there were incredibly friendly and helpful during this.

Of course, my first visit to the place would not have been complete without taking some metal to recycle. So I took some aluminium cans for them, which they particularly appreciated as they'd first have to deal with the beer contained within.

It really is like a toyshop there, except the useful stuff is well hidden. This is what I faced when I went:


I could have spent hours there, but had to be elsewhere so only spent 15 minutes or so. Countless motors there, plus loads of transformers, such as those from microwave ovens, massive utility ones, and a few hefty 3-phase types. But no pole-pig or potential transformers yet (my real desires).

Despite this, I did come away with a beat up old Neon Sign Transformer, which is seen at the bottom of the left photo. And it works it seems! Stay tuned for a quick post on how I tested it "in-heap".

I suspect this will be a regular haunt of mine now, much to the detriment of the girlfriend..