Mostly videos on hobby electronics, test & measurement, ham radio, and other stuff. The site is mainly geared towards the hobbyist. Be sure to let me know if there's a similar topic that you'd like to see a video on! With big thanks to long-time subscriber Dino (KL0S), I've now got an index to all of the videos (arranged numerically and by topic) - see the link at the lower right corner of the channel's head graphic.
11 years on and you're still the best and electronic master. Just to let you know:- One of the finest videos you made was on the CMOS Phase Locked Loop, (CD 4046). That was truly a master class! Thank you Mr. Wolfe!
Hi Alan, thank you for such amazing video, as usual. I always wondered how the "common mode choke" only applies impedance to the coax shield and not the core. I feel like it really makes sense on a balanced transmission line, but when it is applied to a coax, it really doesn't make too much sense to me. (I admit maybe I am just not understanding this properly.) Perhaps a video about common mode choke and how it works on coax (+/- how to measure it??) would be great. Pil VA3GPJ
For those struggling to get DfuSeDemo to recognise the NanoVNA-H in Windows 10. Connect NanoVNA to PC in DFU mode then find the driver "STM32 Bootloader" in device manager right click on it to select "update driver". Choose 'Browse my computer for drivers' and navigate to C:\Program Files (x86)\STMicroelectronics\Software\DfuSe v3.0.6\ (click on include sub-folders in the searching for drivers) then select 'let me pick from a list of drivers on my computer'. You'll see two options; ' STM Device in DFU Mode' and 'STM32 Bootloader' select 'STM Device in DFU Mode' to load this driver. In Device Manager you'll see 'STM Device in DFU Mode' instead of the 'STM32 Bootloader'. You'll find that DfuSeDemo will now recognise your NanoVNA-H. Or at least this worked for me.
Great video, clear, concise and exactly what IU was looking for to test losses on some feeder connectors. An Elmer had told me never to use 90deg connectors as the losses were horrendous. A shame as I really want to use on mobile and portable on my Xiegu G90. Ever the scientist I had to test it and your video was just what I was looking g for. Increased loss of the 90deg PL259 vs straight through PL259 - 0.01dB to 0.03 dB on 7-27 MHz. Guess I'll be using that 90deg connector. Didn't test at6 VHF or UHF - could be very different of course.
This channel is fantastic! The explanations of important fundamentals are clear and the practical applications are always mentioned. I follow along and experiment with each topic covered. Thank you so much for your effort and I wish you all the best!
I can’t get my breadboard twin tee to oscillate! Built it several times using o0.01uf caps, and 20k ohm resistors. R/2 with two R in parallel, same idea 2c. Have used TL081 and ½ LM328 op amps. Voltage from 5 through 12 volts. No oscillation. Can’t understand why
@@w2aew I’ve sort of tried that - how critical is the R/2? I’ve use Rs from the same resistor strip, and they are quite close to the same value, hence my R/2 should be reasonably accurate. But I’ve tried a ten turn pot as well that passes through my desired 10k point, but no joy. Maybe I’m too coarse in adjustment. I’m using the circuit from IMSAI guy , and note he has a 110k R from output to the + input, and a 1k R from + input to ground. How critical is that I’m thinking. I note that you don’t have that in your circuit, but instead lift the voltage a little at the + input to op amp. …… this should be simple, I’m usually working with RF! Maybe there’s an issue with my op amp choice (read availability). I’m in a remote location. Just want a nice 800Hz - ish sine wave oscillator to use for my CW practice. VK4BAC, but unlicensed for XW region.
This might be a little different than the comments you are used to seeing but I came across your videos because I was trying out chatgbt and asked it to write a short story about a boy with autism who solved or figured out perpetual motion and asked it to come up with an idea It’s kinda long but really interesting and you will see how it led me to your page. Every morning, Joshua Daniels would trudge into Parkview High, his backpack heavy with textbooks and dreams. At sixteen, Joshua was different. Diagnosed with autism at a young age, he viewed the world through a unique lens. While his peers reveled in sports, parties, and social circles, Joshua was captivated by the intricate dance of physics and mathematics. His fascination, however, made him a target. Whispers followed him through hallways, and cruel jokes punctuated his days. "Freak," they called him. "Weirdo." Yet, Joshua never seemed to care. He had a singular focus, an obsession that shielded him from the sting of their words: the concept of perpetual motion. Perpetual motion, the idea of a machine that could run indefinitely without an energy source, had been declared impossible by the laws of thermodynamics. But to Joshua, it was a puzzle begging to be solved. Every spare moment was spent scribbling equations, dismantling and reassembling gadgets, and poring over ancient texts on physics. Graduation day arrived, and with it, a culmination of dreams and hard work. As his classmates tossed their caps into the air, Joshua stood apart, a small smile playing on his lips. He had done it. Hidden away in his cluttered basement, amidst a sea of crumpled papers and half-eaten snacks, was his masterpiece. Joshua called it the "Resonance Loop Generator." His breakthrough lay in understanding and harnessing the natural frequencies of materials. He had discovered that certain materials, when combined in precise ways and subjected to specific electromagnetic fields, could resonate in harmony. This resonance created a loop of energy transfer that fed back into itself, essentially creating a self-sustaining cycle. The heart of the Resonance Loop Generator was a specially designed alloy Joshua had created, a blend of rare earth metals and superconductors. When placed in a chamber with carefully calibrated electromagnetic fields, the alloy would vibrate at a frequency that generated more energy than was required to maintain the field. This excess energy could be harnessed and used, creating a true perpetual motion machine. News of Joshua's invention spread quickly. Scientists and engineers from around the world flocked to his small town, eager to witness the impossible. The scientific community was initially skeptical, but rigorous testing confirmed Joshua's claims. The Resonance Loop Generator worked, defying what was once thought to be an unbreakable law of physics. Joshua's invention revolutionized the world. Clean, unlimited energy became a reality, ending the dependence on fossil fuels and transforming the global economy. The boy who had once been mocked and ridiculed was now celebrated as a genius, his name forever etched in the annals of history. Yet, amid the accolades and the newfound fame, Joshua remained the same. He still spent his days tinkering in his basement, lost in the world of equations and possibilities. For Joshua, the true reward was not the recognition but the journey, the endless pursuit of knowledge and the thrill of discovery.
LO1 is only used to select which harmonic of the crystal oscillator is used for LO2. That selects a particular 1MHz frequency range with the drift canceled. The main station tuning is then done with LO3 over the the selected 1MHz frequency band.
That's an excellent demo. I studied cascode amplifiers in an EE lab many years ago. There is an improvement in the bandwidth when a common collector input stage is used. Another way of looking at the high frequency roll off is Cμ is shunted by the collector resistor + input impedance of the CE amplifier. The inverse of this time constant is the main contributor to the high frequency roll off of the cascode amplifier.. With the cascode, the Miller Effect produces a low impedance looking into the emitter of the common base transistor., so the open circuit time constant is much lower. When a CC input stage is used, the input impedance is lowered, so the open circuit time constant is reduced further. The approximation of summing the inverse time constants to calculate the bandwidth is accurate to about 13%, sometimes better.
Just been building your second "sink" circuit - 0.6V across a 120 ohm emitter Resistor with a view to create a 5mA constant sink. That particular circuit was in an exam paper , GCE A level - June 1981 AEB Electronic Systems Paper 1. Testing the sink current in an actual circuit I'm getting about 10mA. The paper also asks for graphs of collector current and output voltage when you charge a 1000uF capacitor.
@@w2aew I thought it could be my "random" silicon npn transistor - I used a C4881 (TO-220) which measured 171 beta on my Peak tester. It appears to have survived being soldered on to a strip-board. The bias config is 2 diodes in series with a 300-ohm 1-watt resistor - dropping 15V - 1.2V.
@@armandine2 Always a good idea to backup your measurements with a second method. For example, if you're measuring 10mA collector current, double check that by measuring the voltage across the emitter resistor, as well as the resistor value - all should lead to the same conclusion - if not, then something is wrong.
Interesting, thanks for making the video - I hadn't seen this design previously! Wondering if you have any thoughts on the durability of the "paddles"? Are the sensors robust or would it make sense to modify the design to somehow protect them?
Great idea! When you only use cw once a year (I know) The keyer contacts get corroded like a set of old set of points in an ignition system. Thanks for sharing and 73.
Nice to see you keying with the "pressure" paddles so effortlessly. I am struggling with my regular CW paddles, may be because I am slow to learn. There was an option for touch paddles with the VU ham from whom I got the usual Iambic paddles. But I did not go for it thinking that it will be difficult to use! 73 de Jon, VU2JO
@@w2aew gotcha. I thought they were relying on the finger's conductivity (completing the circuit between two adjacent traces). But this makes more sense. Less risk for ESD as well.
Wouldn't it work better to add a pair of small diodes and a capacitor so that the lines are pulled to ground rather than about the threshold voltage of the MOSFET? I can see it having compatibility issues with low voltage devices.
I have built a ton of these for myself and friends. They are great and work fantastically. The best part for me is the small size and no moving parts. It’s ideal for use in adverse conditions such as rain, snow, blowing dust, sand, etc…
Sliding out, like a USB stick = clever! I was thinking on a case, also. My idea is a plastic box, with a hole in the top. A small, wooden dowel would go into the hole. The dowel would have a groove cut in it. The paddle would be placed in the groove. Now, the paddle is mounted on vertically and it can be keyed with your finger and thumb, back and forth. A spring, or rubber band, could be added to adjust the pressure. I hope that was clear. Cheers.
A few years ago I built something similar using an Atmel AT42QT1070 capacitive-touch sensor breakout. I wanted to use double-sided copper clad for the paddle, but there was too much mutual capacitance through the FR-4, even with copper etched away leaving only 1/2" pads on each side. I ended up spacing the dit and dah sides (now single-sided) apart with some 1/8" plastic. It's still a single paddle, just a little thicker. Pressure sensors like the VK3IL design uses wouldn't have had that problem. The paddle works great, though, needing just tiny movements of thumb and index finger--not that it improved my sending speed, though. 😕 --Todd K7TFC
Some people actually like to make stuff, and thus learn from the process, and much of the time, building it yourself is much more expensive than buying one.
I too was developing my KX key based on capacitance. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nQtwr_YvNoU.htmlsi=OHyeZZtfPSZZg2id Test your dongle under conditions of poor SWR and an antenna nearby, which is often the case in the field. It took me a while to beat the flood of strong interference when transmitting. 73! UD6ARJ
Very good demo of different transistor biasing methods. Resistors are cheap. I learned this at university and usually design transistor stages with a voltage divider base bias. I never actually did this experiment you demonstrate here, but I have done the math using the Ebers Moll model. This would be a good lab for sophomore EE students
