The Pixie Project - An Exercise in Learning

Here is the current physical stage of my Pixie 2 project.   For those not familiar with the Pixie, its a two transistor and one audio op amp transceiver.  This one is built for 40M.

Its built in what I'm calling Ugly Manhattan.  I put the PCB in the vice and cut grooves with a hacksaw to make the pads.   I like this method, but the pads are bigger than they need to be, and they dictate how the parts can be placed. I've left space for further mods, but if I don't add any then will just cut off the last two rows of pads.

Stage one was to model the Pixie in LT Spice.  If any of you have thought about learning to model in Spice, I encourage you to give it a shot.  Its pretty easy to enter a simple QRP circuit, and its great fun to "Run" it and see the readings at various points.

Once I had the Pixie working in Spice, I tried some mods on it, like adding a phase shift oscillator for generating a sidetone, but couldn't get it to work in Spice.  In fact, I couldn't get it to work on the breadboard either.  I'm going to have to figure out why at some point in the future, but for now I will use my NorCal keyer (which I just built) and it will inject a sidetone into the Pixie's audio chain, hopefully.

Note the two crystals and outboard variable capacator: the Super VXO configuration.  Actually I think it still needs an inductor in series with the capacitor and crystal.  As it is it tunes about 6 Khz.

This is the Pixie, transmitter only, on the Prototype board.  I found this part to be a bit flaky, as I was never really sure if there were good connections at all points, at all times.  To confirm my concerns on this, I note that the rig is much more physically stable when built on the PCB and doesn't have a lot of the noises that I thought might be bad connections on the Prototype board.

Of course the beauty of the Prototype board or Breadboard is that its real easy to plug stuff in and try it and if it doesn't work, then plug in something else.

On the other hand, tracing the circuit when its installed on the board can be tricky.  I made a "map" of the board on paper, drew in the components, connected to their 'row' on the board.  In this way I found one wiring error that I had made.

The whole idea of my "Pixie Project" is to learn.  Learn to use Spice modeling, play with adding modifications, get comfortable with building on the Prototype board and try out different building methods: ugly, Manhattan, etc.

I haven't made a contact with this Pixie yet, but I'm blaming that on messing up my beautiful 550' loop.  A couple of weeks back I added and chopped on this loop to try and get it to load on 160M.  It sort of does that now, but doesn't load well at all on 80M and 40M, so as soon as it warms back up to 0 C, I will drop the loop again and put 50' back in.

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A History of the Pixie from Sprat Magazine844.53 KB

Comments

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What are all the possible ways to build up  body without doing much exercises?

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This is an interesting

This is an interesting project.This Pixie is really quite interesting topic for my research paper and essay writing. Thanks for sharing this new knowledge for me.

Pixie

Think the circuit is working nicely. A circuit diagram will be more helpful to us, I think. Thanks for sharing your work. Waiting for any further modification news.
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That's good. In my opinion

That's good. In my opinion nowadays people are not using their minds in creativity because everyone is using legal steroids to strengthen him/herself but actually it is slowing down the process of your growth.

Fine to meet you, Stephen

Hello, next week I am going to look up all places where you are on Google Earth. Your ears must get red then, Steph.
Well , I have to find out how to insert pics  here  to show sth on that Pixie matter we are talking about.Smile

The problem will be that all these files will be in a neat order  and one can get access very quickly  and differ between 'simple blogs' and projects ideas. One headline could obviously be Hints and Hints ( I  avoid  saying  hints and kinks since it is a book title, hi), workbench tips, your micro in a cork - great!
Have a good start into a good new week.
72, Dieter-bqd

 

Inserting an Image

Hi Dieter,

To insert an image:

  • Place your cursor where you want the image to be inserted
  • Select the 'green tree' just to the left of the Ohm sign
  • Click the Browse button
  • Browse your files and select a file
  • Press Upload
  • File is now in your QRPedia directory
  • Select that file and select TinyMCE
  • Resize your image.  Mine are about 450 wide and 350 high
  • Drag the window open enough to see the buttons and click accept/OK (the left button)
  • Your image should now be in your document.

I hope this helps.

Thank you and 72 & 73 to you.

Stephen

Thanks for breaking it down

Thanks for breaking it down like that, it's much easier to follow.

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Inserting pics - handling the QRPedia software

Thanks , Stephen, The instruction should be on the qrp list as well, shouldn't it?

Pehaps this way  the headline  would be better:
 qrpedia software, inserting pics

Dieter