Eye poppingly bad maps

I haven't written for a while, but I have to now. I have just upgraded my iPhone to IOS6, and I wish I hadn't. (Can I go back?)

The new Apple Maps app is very, very poor.

Just take for example: the village of Chipping Warden, nearby to where I live, is not found in the search and not labeled on the maps.

On the way to here there are two roads labeled "Banbury & Oxford Canal", their is no such thing, it is the Oxford Canal, and its not a road.

The satellite photos are much worse resolution than the previous Google ones. And they are obviously shot years ago, at least 5 years!! As many features have changed since then.

So, bad Apple, bad, bad.

Infact there is no feature of IOS6 that I have found that is better than IOS5...

Morning out with the girls

Our grand daughters have come to stay, here they are out playing:











Then we went to the allotment and climbed trees!

Reprap gets going

After a lot of fiddling with settings in the slicer (slicer) this is the result.

Here are a couple of iPad stands, which need a cross bar the hold them up, but otherwise work well. The design comes from the web site thingyverse:



And this stand along, but rather chunky design:



UNFORTUNATELY

The hot end extruder has developed a leak, and hot plastic dribbles down the side, spoiling future prints. Later… this has been fixed, had to take it off the carriage and tighten it in the heat insulator tube. All now seems well and I have started printing again.

By the way here's the hobby area:

A better SDR Ham radio setup

I have been looking for a while at the conventional ham radio setups. They look like this:



The ATU and TXRX are in the shack, with a long cable to the antenna. The ATU and TXRX can be integrated.

What I have thought of as a better solution is:



The SDR and ATU are integrated. And the control is by WiFi. The box is placed at the base of the antenna. No long feeder cable, in fact no cable at all, except for the need for an AC supply, or maybe a rechargeable battery? The system can be controlled from either a PC, or from a mobile phone or pad. You could offer others to log into a server and for them to control the system?

1st Reprap prints

Got the Reprap printer going!

Some notes about this are below:

* Usefull g-codes are: G1 Xn Yn Enew Fnew: move to coord, new extrusion, new federate. G28 [X0 Y0 Z0]: home [X, Y, Z]. M104 Snnn: Ext temp, return. M109 Snnn: Ext tempo, wait. M140 Snn: bed temp, return. M190 Snn: bed temp, wait. M84: Stop after print job.

Calibrating the extruder. You have to make sure that the extruder consume the right amount of filament. So heat the nozzle up, then feed in filament until some comes out. Then give a command to feed in precisely 10mm and measure what actually goes in, say 13.8mm as ours did. Then you can set the Slic3r parameter Printer & Filament > Extrusion Multipler to 10/13.8 or about 0.75.

Running the printer. Noe: I use a MacBook, and Replicator Host and Slic3r software. MAke sure you have the latest versions installed. After setting up the various parameters in the slicer, and in Repetier Host software… Output an STL file from your CAD software (e.g. from Sketchup), Add this file to RH, check the objects orientation and that it is sitting on the bed, adjust if needed by rotating and shifting. Open Slic3r chose external version and load your configuration then Generate the g-code. Finally check that the right start and end g-code have been generated, and hit "Run".

You can monitor the bed and nozzle temperature as it rises, and then watch the printing happening. IF all goes wrong hit Kill or Emergency Stop.

These are our first attempts at printing as we learnt the Slic3r settings and played about a bit:



Printing



The results after various tries. Not yet perfect. The main problem we have is getting the object to stick on the print bed. Need to try different temperatures.

Using a computer as a scope

I have a MacBook. On the Mac there are a number of programs which can display audio signals as would an oscilloscope. One I like is called Signal Inspector which as well as displaying as an oscilloscope can also display spectra and generate signals. There is another very useful program called PTHVolume which gives you an audio routing selection and gain controls in the menu bar.

The range of the spectral display depends on the settings of the Audio MIDI program where you can chose the A/D sample rate for the audio inputs (up to 96kHz giving a 48kHz bandwidth).

But the audio input to the computer is fairly low level, around 100mV at maximum gain. If you want to check, for example the frequency response of an audio power amplifier then it can have an output of 100V Peak-to-Peak which will severely overload the computers input. On the other hand if you want to monitor low level signal down to just a few milli-volts them the computer is not sensitive enough.

This calls for a preamplifier. And here is one with switchable gain of on the input of 0/-40dB (approximately) and a gain of 0/+20dB, giving a total of 0-60dB range.



Looking at the circuit, the input attenuator needs to be aggressive, for if an input of 100V P-P is to be tolerated and an output of 1V P-P (max) is needed then it should switch 0/-40dB so the lower resistor is therefore just 100R. This would give gain settings of -40, -20, 0, +20dB.

Amateur 40m receiver - will it work?

I have been dreaming again, about very simple but unusual receiver designs for CW and SSB reception. This one is the latest idea:


It has three parts:

1 The input mixer which heterodynes the incoming RF signals with the local VFO to produce an audio signal.

2 A simple audio amplifier.

3 A simple Hartley VFO with electronic tuning using a varicap diode.

The input transformer is a wide band one, using a ferrite core. The diodes are schottky type for low voltage drop. The RFC is 47-100uH "resistor" type. The FETs are the BF245A, a very, very useful transistor which can be used with zero bias (it conducts 2-6mA at a Vgs = 0). The values given here for the oscillator are about right for 7MHz, but may need tweaking a bit to centre the band and adjust the tuning range: to do this a variable trimmer can be put across the 100pF capacitor to centre the thing range, and the varicap series capacitor of 47pF changed to limit the width of the tuning range.

What I want to try also is to connect the output to my MacBook and run an SDR program, this then hopefully will display a +/-48kHz range of frequencies and let me tune across and change modes to LSB/USB or CW. The program I have is DSP Radio from DL2SDR, which works well with my dedicated SDR radio front end, from Kanga products.