That returns several vendors (I am not connected to any). Radial Ferrite Choke Inductor 10uH to 100mH Without wanting to sound cheap but I get my components from eBay :). With regards the inductors, they were definitely both 0.1H. I think though I had a dual gang 20k kicking around and wired it up in parallel. So I hope a late reply isn’t too late to be of use. I have been away from the site looking at programming with Arduinos and building my own, so the VLF has taken a bit of a back seat for the moment.
I have a few questions that you might be able to answer? What is the potentiometer values and are the inductors really 0,1H? They are somewhat hard for me to find and pretty big compared to you images.įirstly apologies, I only just saw that you posted on this thread.
I'm not that strong in electronics yet, but your post are helping a lot, so big thanks for that! I have had really good experiences with you take on the peanutbutter vlf reciever and are now trying to build the bbb-4 with headphone amplifier. Impressive, you will learn lots from this project. Next I will try tinkering with the radio output so that it goes into the Arduino and gets logged, though at the moment I am trying to get the new version radio laid out and the narrow band filter working. Hahahahaha!Ī little underwhelming, but baby-steps and all that. The radio comes on at ~57.75 seconds, is on for a second, then goes off. I gather these can take a maximum of 200mA - the radio seems to draw 150mA so I think it might be okay.Īnyway, I got the radio hooked up to spectrum lab and several weeks of work/frowning gave me this Today I have been trying to get #4 modified to turn a radio on and off the bit in the red box below is the transistor switch (2N3904 transistor). My thinking is that if I can master all the above I have the basic ingredients for my logging module.
#Comm. quarterly winter 94 vlf receiver how to#
I have been learning how to program an Arduino ('Exploring Arduino' by Jeremy Blum) and have been able to ġ) Detect a varying voltage (used a spare potentiometer)ģ) Log results from #1 and #2 to an SD card every minuteĤ) Use a transistor as a switch to turn on an LED So the radio and filter will be posted eventually here, but I might start a separate Arduino data logger thread.Īnother slightly underwhelming update approaching, but I am feeling a bit chuffed. That way I can see if I can get the variation in voltage logged by an Arduino datalogger and use that for SID detection. The next stage is to clear the prototyping board as I want to put together a version of this radio that is tuned to just one of the VLF transmitters. I have a few ideas for how I want to improve the layout in future versions, but for the moment I will leave it as is. Gain is set to minimum.įrom a visualisation point of view the filters do not seem to make much of a difference, but for ease of listening they do.īoth plots show sferics (vertical lines), VLF transmitters (solid horizontal lines), and I think the intermittent horizontal lines are Russian Alpha transmissions. There are still harmonics, but they are not as loud. The BBB-4 with high pass filter attenuates a lot of this (little signal below 1kHz). Mains hum is very obvious right at the bottom of the plot, and it really overpowers all but the loudest sferics when listening. First screen capture is the unfiltered peanut butter radio I also have fired up SpectrumLab in my back garden to see if me messing about with filters has made a difference (the BBB-4 with the filters certainly sounds more pleasant than the unfiltered Peanut Butter VLF radio). So if the amplifier was given a fixed gain, it would be possible to squeeze it into the smaller case. I have compared the physical size versus the first one I made, and I think the boards are comparable in size, looking at it now I just needed the larger case be able to handle two potentiometers (left pot is gain, right pot is on/off and volume).
#Comm. quarterly winter 94 vlf receiver pdf#
Anyway, this is the latest pdf after some post build changes īBB-4 VLF radio with headphone amplifier.pdf I had plans to make a nice insulated shoe for the circuit and battery to sit in, but in the end I opted to use silicone sealant and glue them in place.įurther down the line I am going to redesign the circuit so that the potentiometers are soldered directly to the veroboard, but I am happy enough for this version to have flying leads all over the place. In the end I traced to it a loose connection caused by me tugging on one of the leads. Well, they took 10 minutes to change, the following 2.5 hours was me trying to work out why the radio had stopped working. After a bit of work today the potentiometers got sorted.
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