AE EP#47 Raspberry First Steps

Sooo, I finallly got around setting up my raspberry, nothing too special but maybe it helps some people.

The thing with the screen was rather easily resolved (if only I could have been able to see something :).

It involves pretty much tinkering and the trapezoid picture of the tube didn’t help.
In the end I added to the /boot/config.txt file to this:

overscan_left=18
overscan_left=10
overscan_left=-1
overscan_left=-25

The framebuffer_width/height are set back to normal.

AE EP#44 Simple Electronic Dummy Load

Several years ago Dave Jones posted a vid about a very simple current sink and I wasn’t too successful replicating it then on prototyping board and went on to make one a little different. lately I wanted to go back and do it properly this time to test the mini-psu’s and the sources on my broken Tektronix 2236. I think it became a neat little build and plan to expand on it putting it into the multi module case with some atmega and 7-segment displays. Here is the vid:

A zip file containing everything is here: DC_load

The rendering of the Design…
board_render_cut
…and the real version:
IMG_5671

whoop whoop

AE EP#42 Selfmade PCBs – My Way

Finally I took matters to to an end and got me a new laminator since the one I had before was /way/ too big for my new flat. It has two heated drums which is important to have an even heating and so prevent warping. Of course this does not prevent it altogether (2 materials) but it is way better than the one heated drum before.

The thing is called Peach PL713 but its not available on amazon right now (only the peach “photo”). So mybe you can find one just as cheaply at your local office supplies store. For Etching I use sodium persulfate With 100g per 500 ml (go metric! :D). Have fun and see you next time!

AE EP#41 Poor Mans HV Probe

I was trying to repair my tek 2236 and was in need of measuring a -2kV line, only problem: my best Multimeter can only do 1000 V so I had to yank up 30 3k3 Ohm resistors in series to make a 100M Ohm Resistor. All put into some trash plastic tube makes a usable series resistor for the MM.

Be sure to watch the safety advice and keep your hands off the circuit under test!
Have fun!