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  • dr_phil commented on dr_phil's instructable Wood Pile "book End" Supports From Pallet4 days ago
    Wood Pile "book End" Supports From Pallet

    Thanks - mine haven't collapsed yet! Not even close, as far as I can tell!

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  • dr_phil commented on dr_phil's instructable Arduino-controlled HDMI Switch1 week ago
    Arduino-controlled HDMI Switch

    Hi Edward - you could probably substitute the high-side PNP transistor switch with a relay, if you wanted a conceptually simpler circuit (albeit with an extra wire). The transistor method really is easy though (even I could manage it...!). I don't know how the current draw would compare between a transistor and a relay coil, however, but suspect that the relay will be more power-hungry.Good luck.

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  • HF Antenna Analyser With Arduino and DDS Module

    Thanks Paulo. Sounds like you made it? If so I hope you find it useful (and worth the effort of building!).I have just updated the firmware to include 160 m and 60 m (and all the bands still just about fit onto the OLED display). When I've done the calibration I'll upload V7. Watch this space...

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  • HF Antenna Analyser With Arduino and DDS Module

    Hi Chris - thanks for letting me know. I hope it proves useful to you. I've bought a phase-sensitive detector module from ebay recently which I'm planning to incorporate into the design instead of the bridge. Watch this space (eventually!).As far as the box goes, I just picked sometime that looked okay off ebay uk. It's broadly classed as an instrument enclosure (abs body with aluminium ends). I don't think it was branded in any way. Just looking at the layout of your board, you might be better off using a simple acrylic (plexiglass) sandwich with holes for the encoder and the antenna connector. Use PCB standoffs to support the plates. You get screen protection for free if you do this!Thanks again...

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  • HF Antenna Analyser With Arduino and DDS Module

    Good work and thanks for letting me know! Did you reverse engineer my stripboard layout or do your own from the K6BEZ layout? I'm guessing that the arduino is hidden underneath the copper groundplane?

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  • HF Antenna Analyser With Arduino and DDS Module

    Hi Steve. You make some excellent points. I like the idea of an in-built cal routine (but I have to remind myself all the time that better is the enemy of good enough!). Anyway I've just found out how to extract the hex file and will email you one if you want (if it's not a breach of protocol and I can figure out how to attach stuff!).I tend to put my projects together with cheap, compact Nanos and other import modules. Once the firmware is finalised I box it up and do nothing except change the battery occasionally. Your point about the OLED is a good one - in the driver file there is a huge range of options and you almost have to guess which display you have. It's worth it though, as these are crystal-clear, bright displays and even the graphing works well - I'm not sure how a classic ...

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    Hi Steve. You make some excellent points. I like the idea of an in-built cal routine (but I have to remind myself all the time that better is the enemy of good enough!). Anyway I've just found out how to extract the hex file and will email you one if you want (if it's not a breach of protocol and I can figure out how to attach stuff!).I tend to put my projects together with cheap, compact Nanos and other import modules. Once the firmware is finalised I box it up and do nothing except change the battery occasionally. Your point about the OLED is a good one - in the driver file there is a huge range of options and you almost have to guess which display you have. It's worth it though, as these are crystal-clear, bright displays and even the graphing works well - I'm not sure how a classic 'lined' LCD would work. Much of my stuff ends up using every pin so I'm a bit of an I2C fan. This project has quite a few pins left over at the moment.I'm keen to update this device to measure the magnitude of reactance, so I can plot minimum SWR and reactance null simultaneously. If it's easy it could happen quite quickly. If not, I'll move on to the next project in my brimming in-tray! Watch this space.Best regards, dr_phil

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  • HF Antenna Analyser With Arduino and DDS Module

    Type "30dB low-noise LNA Broadband Receiver Module RF Wideband Amplifier 0.1-2000MHz" into ebay and you should get a few hits. I couldn't find a part number.I should stress that I make no recommendation as to the suitability of this device (as mine hasn't arrived yet). I think the problem of detector non-linearity will remain at low return signals. In my opinion the software-based calibration described in the instructable is the easiest and cheapest way to go. It is also fully supported in the sketch (version 6).

    I'm not familiar with this method of flashing the Arduino; it sounds very sensible for a production-type environment. In this instance I think the user community is best served by compiling from source, so they can calibrate the measurements, understand the code and customise the device if they wish.

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  • HF Antenna Analyser With Arduino and DDS Module

    Hi Ambroigo,I've put additional information on Steps 2 & 3 which shows where to connect the screen and encoder to the Arduino. D2, D3, A4 & A5 must not be changed (because they provide hardware interrupts & I2C support). The other digital pins to interface with the DDS etc. are optional and can be changed in the sketch.The sketch (.ino) automatically interfaces with the OLED and encoder. When performing a single or multi-band scan, frequency and VSWR values are sent out of the serial port on the back of the unit. The easiest way to get these is to connect up your USB Arduino Uno-style programming lead and start up a 9600 baud serial monitor via the Arduino IDE. Then copy and paste the results into a spreadsheet.

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  • HF Antenna Analyser With Arduino and DDS Module

    er, sorry - Step 2!

    Hi and thanks. I will look at producing a schematic as there is a lot of unexpected interest. Nevertheless all the detail is in the instructable if you look carefully.

    Hi. You can find the schematic for the basic VSWR capability via the link on Step 3. Look on Page 7. This doesn't include the encoder and the screen. I didn't expect this project to create such interest so I will have a look at creating a comprehensive schematic for the whole system. It will take a little while though...

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  • HF Antenna Analyser With Arduino and DDS Module

    Hi. See http://www.hamstack.com/hs_projects/k6bez_antenna_analyzer.pdf. Page 11 refers to a simple resistive bridge. I think the implementation on the board is more complex as Page 11 only shows a single diode. I haven't gone through it in detail, but I'm glad it seems to work!

    Thank you. If you want the schematic, check out K6BEZ's website for his original circuit, which I've borrowed largely unchanged. I have however added the rotary encoder and the screen etc. which hopefully any Arduino fan should be able to follow or adapt to their own specification. If not I'll try to answer specific questions. For what it's worth, it usually takes me ages to transfer a schematic onto stripboard and I'd love it if someone did that job for me; it's interesting to see so many people wanting it the other way round. :-)

    Thanks. I didn't present the schematic because a) the fundamental VSWR part is K6BEZ's work and is documented extensively on his site; b) the idea is to tell you how to make one of these, not go into the detailed function of the system. Hope that makes sense :-).

    Yeah, I just love those OLED displays - small but very clear and easy to read.You could probably convert this if you a) had an appropriate DDS module covering the relevant ranges; b) your resistive bridge (see comments above),and associated circuitry and wiring were appropriate to the higher frequency. If all that's okay (and I've no idea whether it is), you just need to change the contents of the array that stores the HF band information.If you do it, please publish!

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  • HF Antenna Analyser With Arduino and DDS Module

    Hi again. Thanks for the tip; it certainly sounds very easy (once you know how). In my defence I don't have a key. I'm working on learning CW but haven't got far enough with Koch to justify buying one yet.

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  • HF Antenna Analyser With Arduino and DDS Module

    Hi & thanks for your interest. I'm really sorry but I couldn't face making another one. It took me several months (off and on), but in fairness most of that was getting the code right (and making the rotary encoder work properly). The good news is that bit has now been done for you. It's really easy to build a bare-bones version (two or three hours work) and you just need to put my sketch onto it.Alternatively you may wish to consider one of the very cheap Chinese units from Ebay?

    Thank you. Sounds like you have way more experience than me in the field (that's not hard, mind you!). I'm usually really pushed for time and the finer points of antenna design and tuning are beyond me at the moment. I spent out a load on a new rig and didn't want to trash it with my inexperience! Hence the analyser, which gives me peace of mind and saves me time if and when I change the antenna.Your DDS seems has demanding supply requirements. The one I used cost about £6.30 and uses a 5 V rail. It will go up to about 40 MHz. Good luck with the project though.

    Thanks. Erm, seriously I would probably buy the cheap Chinese analyser for about £45. Getting my basic system working was pretty easy, but making it work well and look nice took ages. What's your time worth? Like all these things, it's economically usually a bad idea but you learn loads and get lots of satisfaction.The encoder is really nice but honestly, it would have been much cheaper and quicker to use push-buttons.For a future build it might be nice to try to incorporate resistance and reactance measurements, but at the time it was all about not blowing up my finals!

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  • dr_phil commented on dr_phil's instructable Kids Screen Timer with Arduino7 months ago
    Kids Screen Timer with Arduino

    You're welcome and thanks for your kind words: sharing has helped me hugely so I try to put something back. The TV isn't getting much use at the moment so you'll have to wait for all those additional features I talked about... perhaps consider them a challenge and post your results when you've done them?! Good luck with Arduino...

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  • dr_phil commented on SimonM83's instructable Improved Arduino Rotary Encoder Reading8 months ago
    Improved Arduino Rotary Encoder Reading

    Excellent work Simon - thanks very much for sharing. Adding to Githyuk's observations, I have also found that this works well with a two detents per pulse encoder. I previously tried a KY-040 'module' with a 20 pulse/20 detent device, and performance was too jittery for a menu system. This is a bit of a shame as the 30/15 devices are relatively expensive (~£6 or more), especially if you want a switch and a threaded body. Now if we could just figure out how to get the cheapo ones to work... :-)

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  • dr_phil's instructable Coat-hanger hook for hotels's weekly stats: 9 months ago
    • Coat-hanger hook for hotels
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      2 comments
  • dr_phil commented on dr_phil's instructable Kids Screen Timer with Arduino9 months ago
    Kids Screen Timer with Arduino

    Hi. Simply find the line in loop() which reads 'timeWindow=0' and change it to 'timeWindow=1'. Then the display should read 'xxxx tAG' all the time and all users can log in any time.Cheers

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  • dr_phil commented on dr_phil's instructable Kids Screen Timer with Arduino9 months ago
    Kids Screen Timer with Arduino

    Hi. The concept is as follows:Let's say you have two kids and you think they should probably be allowed up to 2 hours of TV a day. This is already coded but you can change it.Let's also say you don't want them watching TV in the morning before school, and after about 6pm when they should be eating and getting ready for bed. These time 'windows' can also be coded separately for Mon-Fri and weekends.The kids will be able to watch TV when a) they have minutes on their 'account'; and b) when the time is in a permitted window (e.g. 3pm to 6pm). When these conditions are met, they still have to swipe their tag to 'log on' and switch on the TV signal.You know when the timer is in a permitted window because it says 'tAG' instead of 'off'. When it says 'tAG', the kids can switch on the TV signa...

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    Hi. The concept is as follows:Let's say you have two kids and you think they should probably be allowed up to 2 hours of TV a day. This is already coded but you can change it.Let's also say you don't want them watching TV in the morning before school, and after about 6pm when they should be eating and getting ready for bed. These time 'windows' can also be coded separately for Mon-Fri and weekends.The kids will be able to watch TV when a) they have minutes on their 'account'; and b) when the time is in a permitted window (e.g. 3pm to 6pm). When these conditions are met, they still have to swipe their tag to 'log on' and switch on the TV signal.You know when the timer is in a permitted window because it says 'tAG' instead of 'off'. When it says 'tAG', the kids can switch on the TV signal by swiping their RFID tags. Then their minutes start to count down, till they swipe again and log off / switch off the tv signal.A parent or holder of the timer tag can use the TV at any time (you pay the bills, right?). Only normal users (i.e. kids) have to wait for 'XX:XX tAG' to appear.Hopefully this make sense. Perhaps I need to check my write-up...Cheers

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  • dr_phil commented on dr_phil's instructable Low-cost Bare-bones Bench Power Supply1 year ago
    Low-cost Bare-bones Bench Power Supply

    Thanks for your kind comments. It is, as you say, exactly what it needs to be (for me, anyway)...

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