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 on: June 26, 2019, 09:02:13 09:02 
Started by cyber_drifter - Last post by zac
the share jpg file not shown correctly please re-upload

I replaced the jpeg file in my original post.  Not sure how it was corrupted. 

Posted on: June 26, 2019, 08:34:33 08:34 - Automerged

This video is taken during daylight showing a different phenomena back in 2011. Note the "flash" near the middle left side at the 49 second mark.

This is a short clip from a medium resolution (320x200) thermal imaging camera. It shows me walking up the stairs and the entry area in my house which is the same area shown in the other video with the PIR lights inexplicably turning on.  I didn't record anything that appeared paranormal with it though I had it tied to a recorder for a week that recorded on perceived motion (changes in the image).

 on: June 26, 2019, 08:06:30 08:06 
Started by cyber_drifter - Last post by sadman
For anyone interested, attached is the schematic for the digital dice device I mentioned. 

the share jpg file not shown correctly please re-upload

Posted on: June 26, 2019, 07:32:50 07:32 - Automerged

here is book on theory and practical approach to subjected topic theremin is an other close approach hope this will help you a lot



 on: June 26, 2019, 06:55:53 06:55 
Started by HARESH PARIKH - Last post by HARESH PARIKH

 on: June 25, 2019, 09:26:23 21:26 
Started by Nema99 - Last post by zac
This member is invited by me. Registration isn't completed yet.

Note: This message sent by the system behalf of zac.

 on: June 25, 2019, 08:59:32 20:59 
Started by cyber_drifter - Last post by zac
What do you think about these?

This video shows a electronic dog toy (ball) that lights up when it is thrown and hits the ground lighting up spontaneously while it was on a table undisturbed for at least several hours. I have had dozens of these toys for 5+ years and have never seen one light up spontaneously before. This happened a number of times that day (which was also my birthday), but I have not had it happen before or since then.

Trigger is at 23:35:05

Video of 2 battery power motion sensor lights in my entryway being triggered:
(trigger at 1:37:54)

Video of the same area from behind the motion sensor lights:
(trigger at 1:37:50--the clock in this camera is a few seconds offset from the other one)

It is interesting that both motion sensor lights turned on within 1/30 of a second of each other (frame rate of the video being approximately 30 frames/second). Other motion sensor lights lining the stairs were not triggered.

Video of the same location, but with 3 lights being triggerd though not all within 1/30th of a second as in the other video.  Trigger at 00:24:43

The motion sensor lights are this model which use a PIR sensor:

 on: June 25, 2019, 12:41:04 12:41 
Started by Hellscrom - Last post by Hellscrom
NoteEE student. I'm currently working in biology industry developing firmware for embedded systems based products.
I would like to join so i can become a better developer by sharing information amongst peers.

 on: June 25, 2019, 06:26:00 06:26 
Started by Magnox - Last post by Wizpic
I use the latest version, luckily Iíve not had any issues so far but then again Iím only a hobby person and not a company. Only use it from time to time.
It is easy to use if you have used other pcb software.
My designs donít get that complex so I use my CNC to make a one off for testing and if all is good and I need more I just get my pcbs from e-bay very cheap for 10 off, canít be done with the chemicals these days very messy.

 on: June 25, 2019, 05:09:40 05:09 
Started by Magnox - Last post by Magnox
Thank you Wizpic! Yes, it's all a learning experience. That's what I want, and why I want to design my own things rather than just take the easy option and grab someone else's from the 'net. I want the challenge.

Which version of Altium do you use? I'll take a look at it. I've been trying to decide which software to settle on, but I don't want to spend ages trying out and re-learning every software package when I could be concentrating on making things instead. I'm not familiar enough with any of them to have a preference at the moment. I need to pick one and stick with it.

I use Multisim often for testing things out, and I have a big, partially finished project done on Proteus from a few years back that I might resurrect.

My designs go up to relatively complex things (for a hobbyist) with CPLDs and small FPGAs, so software suitable for perhaps a four layer design would be beneficial.

Being able to have PCBs made, affordably, is a game changer for me.

Edit: I've just remembered why I had not considered Altium: all the talk about codearmor and Altium trying hard to identify unlicensed users. Although I have good firewalling in place, I don't like the thought of that.

 on: June 25, 2019, 12:42:04 00:42 
Started by Magnox - Last post by Wizpic
Congratulations on your project, well documented and presented. Something Iíve never really played with may be one day, thatís the beauty of working on projects you lean from your mistakes and learn more along the way. Itís like my wireless meter I did, the first one worked really well but then the second one I did where I improved on the design changed the case which was better suited and now looking at making mk3 of it with itís own integrated battery/charger built in.

Iíve never used kidcad Iíd recommend Altium a bit of steap learning curve but the best program by far in my opinion

 on: June 24, 2019, 08:51:51 20:51 
Started by Magnox - Last post by Magnox
This is the first step in making myself a GPS disciplined 10MHz reference oscilator, followed by a frequency/timing counter. It would probably be cheaper just to buy them, certainly easier, but I want to design and make my own for the fun of it. I made a bad mistake in this design which I didn't realise until after I had populated the PCB. It doesn't stop it working for what I want, but it's very annoying after all my hard work! I blame my recent cognitive problems (seriously). I'll get to that later anyway.

The receiver is based around a Ublox NEO-M8T module. That is the timing-enhanced version of their feature-packed GPS receiver module. The module comes on a tiny PCB with castellated edges for soldering to another PCB. It includes the GPS receiver itself, flash memory and antenna LNA/filter/power. Nicely, it has a USB interface built in (really a serial-USB converter) to make PC interfacing easy. In addition to the usual 1PPS (pulse per second) output which is the key to using these things for timing, it has a second timing output. Both are reprogrammable to a wide range of frequencies/periods/duty cycles.

This is the first proper thing I've designed in years. While quite simple, it had a bit of a learning curve. Impedance controlled PCB microstips for the antenna and USB and hand soldering 0603 components among them. I decided to have the PCBs made by JLCPCB. There's no way I could hand make a good enough one.

I wanted the board to be suitable both for prototyping and learning to use the thing, followed by using it in the final GPSDO design. I can't afford to buy a second NEO-M8T for that. Hence some of the design decisions.


The circuit requires 3.3V and can be powered from 5V, 3.3V or USB bus power. USB bus power can be enabled with a jumper. I wanted to be able to disable that completely when I put it to its final use (no way USB can power the GPSDO) but it's useful to have for prototyping at first. A couple of diodes and a LDO regulator take care of either 5V source. The regulator is fine with having 3.3V applied at the output if there is no 5V, according to the datasheet. One should only connect 3.3V directly if there is no 5V source. A CR1220 cell keeps the NEO's memory when not powered, to make startup quicker.

Although the NEO already has an additional LNA inside, an active antenna is still advisable if it is on a long cable. The NEO has a filtered, 3.3V power output to drive the active antenna but lacks a bias-T, so one is required. The trace from the module to the antenna is a 50 ohm microstrip with the bias-T and ESD protection connect to this trace directly with no stubs. The bias-T power can be enabled or not by the zero-ohm resistor link R13, just in case I want to use an unpowered patch antenna in the future. Currently I'm using a TomTom external, active GPS antenna I picked up cheaply.

The USB interface has a TVS protection device and the proper 90-ohm differential pair microstrips to the NEO. Well, near enough anyway. A standard asynchronous serial interface is also available on the header pins, at 3.3V, for connection to an MCU. The serial interface can be changed to SPI by fitting a link at R12.

The all-important timing outputs are available on both header pins and SMA connectors, each with an individual buffer. Here is where I made the mistake. My first design used TinyLogic individual buffers for these, an idea I borrowed from ublox's own development kit. At some point in the design I thought it would be simpler to change these for a single IC, a hex buffer. I completely forgot about my intention of being able to drive a 50ohm load. The single IC cannot handle the current required for that. So, despite having 50ohm microstrips to the sockets and termination resistors, it needs to drive a high impedance load. That's not likely to be a problem really, given the low frequency and short connections, but it's really annoying to have made the mistake. If necessary I could probably bridge two buffers together with a bit of wire under the chip to get enough current for one 50ohm load. Of course, I realised this after I had built the board up. If I could afford another NEO module I would go back to the original and have another PCB made.

I used Saturn PCB Design Toolkit (free software) to calculate the microstrips. The PCB is made from 0.8mm FR4 because 1.6mm needed much wider microstrip traces. A drawback of only using two layers. The PCB could have been made half the size, but I wanted to make it easy to use. Besides, it's the first design I've done with almost exclusively SMD parts, and the first I've ever had made for me.

I'm still playing around with KiCad and I've attached the design files in case anyone wants to make one. I'm not sure I like KiCad though. My next design might be with something else. Note that I've included some libraries for the parts, including two for the NEO. I used one (from the repository) in the schematic, only to find the PCB footprint was wrong. So I found another one with a correct footprint and used that for the PCB. C7, C13 and C15 are ESD protection devices, not capacitors. KiCad gave them that symbol from its library, silly KiCad.

The board works (other than the 50ohm termination thing) perfectly. I populated the power parts first and checked power lines, because I didn't want to blow up a very expensive NEO-M8T. Then the rest of the components apart from the NEO and another continuity check and voltage level check on important pins. Finally, I soldered on the NEO itself. That was a pain to do. The castellated pads didn't seem to want to take solder on some of them, probably ground planes, even with my 'big' iron tip. I did most of the soldering under a 20x binocular microscope because my eyesight is so bad I can't even see an 0603 on my desk without my glasses now (literally).

Seeing the PPS LED start flashing about 15 seconds after I applied power from a PSU was so good! That meant that I hadn't managed to kill the NEO with the dodgy soldering; it had got a satellite lock and was functioning. The NEO 8 is really sensitive. My antenna is inside on the windowledge and other GPS units really struggle to get a signal there; I usually have to hold them out of the window for a few minutes while they find some satellites. The NEO 8 took 15 seconds from a cold start to be up and running!

The board also works fine from USB power and talked nicely to the PC. It shows up as a virtual COM port. Ublox's U-Center software talked to it, as did Lady Heather (a free, very useful program for GPS timing systems). Within a couple of minutes of powering up again, it was tracking so many satellites they were overlapping on the display. I used U-Center to program the NEO to fixed location timing mode, and the second timing output to 10KHz and checked outputs with a 'scope. All is as it should be.

Next step... use this to prototype my GPSDO. More designs (hopefully with fewer mistakes) to follow when I figure out how to make that.

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