Wednesday, 8 April 2015

Electronic Transistor / Diode / Resistor / etc. Tester

I always manage to end up with a few transistors which have lost their markings or lost the pin out data for those which are labelled. Looking on eBay at the bare bones electronic testers with graphic display from China I finally decided to invest £15.99 including shipping. It finally arrived today, well wrapped in layers of bubble wrap and all ready to attach a 9V battery. (not provided) There are no instructions with it but most things are very easy to work out.


Lift the lever of the ZIF (zero insertion force) socket, put a transistor in three holes, push the lever back down to clamp the leads and press the red Test button.  Make sure the transistor goes in holes marked 1, 2 & 3. Any set will do.


First the display shows the battery voltage and says it is testing.


Then once it has worked out which way round the transistor is and what type it is the display changes to show that information, along with gain and a couple of other parameters I haven't sussed out yet. It won't give a transistor number but knowing which type it is and which pin is which is a great boon. Better than a pile of unidentified transistors.



It will also test resistors:


diodes, including LEDs:


and also capacitors, which I haven't tried as yet.  The listings stress that capacitors must be discharged before testing otherwise the tester could be damaged.  On this quick test of  it I am impressed, well satisfied with the investment and will find it very useful around the shack.

Wednesday, 31 December 2014

Cyntech Unhelpful

On 29th Sept I ordered an HDMIPi Deluxe from Cyntech (an HD display designed to hold a Raspberry Pi behind the screen). After various delays I was informed on 18h Dec that it had been dispatched. I waited patiently until mid-day Christmas Eve and when it hadn't arrived I emailed Cyntech only to get a standard reply that they were closed for the Christmas period.

I got the same message when I emailed them this Monday and again today (Wednesday 31st Dec.) It's all right for some. Most companies are working hard on normal working days between Christmas and New Year but not Cyntech who, in my opinion, are exhibiting very poor customer relations.

As a result I have no way of knowing whether the company still really exists or whether the item was lost in the post or what. Therefore I have now opened a dispute through PayPal. It was fortunate I took the precaution of paying through PayPal as I have found them to be excellent at customer relations and they have never failed me yet when I have had the occasional dispute.

Thursday, 30 October 2014

Improved piaware Reception

After running piaware on the RPi B+ for a few days I was reasonably pleased with the reception but wanted to have an antenna outdoors. It would have been a fairly difficult job to try waterproofing my home brew collinear so after a look round the web decided to order a TMRF-1090 from Taylor Made RF Ltd.

I fitted it to the top of my mast so it is just above the roof of my bungalow and connected it with Heliax half inch FSJ low loss coax which I had spare. The antenna is sturdily built and well finished. The simple instructions with it made it a doddle to fit together. The Heliax is very stiff so it goes as far as the entrance through the bungalow wall and then connects to RG213 the rest of the way with a short flexible link to the dongle.

DSCN3664     DSCN3663

Once connected up it was a case of seeing how much reception would have changed. Would the TMRF-1090 be worth the time, effort and money? I needn't have worried as can be seen by the increase in the numbers of aircraft tracked in the statistics from FlightAware:

Data 2014-10-30

A little video of real time tracking using piaware with FlightAware on the Raspberry Pi B+:

Friday, 17 October 2014

PiAware on a Raspberry Pi B+

Browsing the various RPi related tweets I follow I had a look at RasPi Weekly Issue 71. On there I saw a link which caught my attention. Some time ago I had software running on a PC which used a DVB dongle to collect aircraft position information and plot their positions in real time on a map. The link related to some software (PiAware) to do a similar sort of job using the Raspberry Pi and led to the Flight Aware site.

I still had my DAB dongle ...
 10316324615_33fc029e31_o     DSCN1909a
... connected to my home made collinear aerial in the roof space.
Details for making the aerial can be found on Radio Antics.

After downloading the software and fitting the dongle it didn't take too long to get the software working and sign up (free) to Flight Aware. This is needed as the RPi sends the signals it receives to their servers. Next a web browser is used to log in to the RPI and the information is plotted in real time on a map:

Clicking on an aircraft brings up information about speed and height on the right and a line shows the track it took while my system was able to receive the radio information.

I was hoping to be able to see the map on the RPi's own monitor. So far I haven't discovered how, or even if it's actually possible.

Thursday, 25 September 2014

PIR to control USB camera

One of the things I want to try out is automatic recording of birds which visit the bird bath so the idea was to use a passive IR movement detector to tell the RPi when to record a photo from a USB camera.

It took a couple of hours scouring the net to find all the information I needed along with lots of failed coding attempts but eventually I got the idea to work just as a test layout in the kitchen. Very few components are needed - the Raspberry Pi (B+ in my case), the USB camera and the PIR:
(clicking on a photo will open a larger copy)


Of course a screen, mouse and keyboard were attached while coding.

Cobbling together several pieces of code from different sources resulted in:


modules loaded:
GPIO to acces the pins
time to be able to add delays where needed
os to give access to fswebcam code

N is a numerical counter which increments each time a photo is saved and added as a four digit number to the file name.



Next will be to get the photos saved on a USB stick instead of the micro SD card.

Saturday, 20 September 2014


I ordered a BerryClip+ kit of parts from Ryanteck Ltd. In one of my fastest Round Tuits I had all the parts soldered in about an hour. Included in the parts are 6 LEDs, 2 push switches and a buzzer. The BerryClip+ is the red board:

BerryClip+  DSCN3468

By going to it is possible to download instructions as none come with the kit. Included in those are details of how to download a set of Python test files so all available facilities on the board can be tested.

It was a great relief when all 10 test files worked perfectly first time.
Here are two of them in operation:

For non morse readers the message should read "hello from m1btr"  (my amateur radio callsign).
The morse message is typed into the RPi and then the routine sends it in morse to the red LEDs and the buzzer.

Sunday, 14 September 2014

The Ups and Downs of a USB Camera

As I keep having problems with the RPi camera I've been having a play with USB cameras on the Raspberry Pi B+.  I have a couple of oldish USB cameras I used a few years ago when I used Skype. They both work on the RPi OK once fswebcam is installed. I also have the RaspiCam Remote app installed on a Samsung Galaxy Tab2 so that the photos can be sent from the RPi to the tablet through my wifi network.

RaspiCam Remote just needs the IP address of the RPi to make a connection and load shots from the USB camera. I find it's a bit temperamental and needs re-starting from time to time, especially after the Samsung goes to sleep.

The setup was tested with everything set up in the kitchen and the pictures from both cameras were reasonably good.

USB camera 1410610257699

What I was hoping to do was set up a USB camera with the RPi in the Summerhouse so it could look through a side window at the bird bath. Unfortunately it would appear that USB cameras are probably set up to work in relatively low light indoors and both were overwhelmed in daylight, even when it was cloudy:

USB camera

Once daylight had partly faded the results were better:

USB camera

I will have to have a long think, experiment some more and do some searching. The present setup would probably be OK on dull days in the Winter.