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Please leave the long signature lines at home. Most especially, those involving sports, politics, or religion. Do not respond to this on the list. -- Steven Greenfield AE7HD

The main purpose of a schematic is to communicate how a circuit is connected and operates. https://electronics.stackexchange.com/questions/28251/rules-and-guidelines-for-drawing-good-schematics https://www.k-state.edu/edl/docs/pubs/technical-resources/Technote8.pdf https://www.ae7hd.com/2023/05/how-to-draw-schematic-diagrams-by-paul.html -- Steven Greenfield AE7HD

Looking for good recommendations on a battery powered soldering iron. Precision work is a requirement, doesn’t need to work for hours on end, 1/2 hour every now and then is enough. Any recommendations from your experience? Thank you Nuno T. -- Nuno T.

Hello,In the circuit below I have Vc>Vb. I need some how to make Vb larger then Vc. I there a method using R1 R2 and R3 which could swith the Vbc junction state? Given the circuit how can I make the Vcb juntion reversed biased? Thanks. Ltspice file is attached. /g/electronics101/files/john233/03_04_25.zip

Strictly speaking this isn't electronics but I've noticed many people who are into electronics also play guitar (and conversely, many people who play guitar are into electronics.) I've "played" guitar since I was 12, the first years things were kind of ragged but more because I had a batbox instead of a decent guitar. I've hated changing strings, really dislike with an unhealthy intensity. A friend suggested "locking guitar tuners." ok them up, [also look up "locking tuners" you'll get some different hits) There are so many different brands and the quality appears to vary with a brand randomly over time. It takes me all of 10 minutes to change guitar strings now. Another thing that is at least electrical in nature is never cut a high B or E around an electrical outlet. https://sound-au.com/guitar-string.html While most AC outlets with a male plug in it is at risk the US NEMA 5-15R, if mounted "improperly", is especially at risk. Heck, even if it's mounted properly it is still at risk. FWIW, the NEC now requires the grounding connector be placed on top "where practicable." This reduces the risk of a metallic object falling in the outlet and getting welded between hot and neutral. Don't laugh, I've seen it happen 3 times in my life, all involved coins. And if a bit of flying B/E string lands inside your tube amp while it's on....things can get way too interesting way too fast. That's never happened around me but I've talked with guitarists who lost amps they really liked. It is a good idea to wear safety glasses and use a small pair of hemostats to clip on to the end that is being cut. The mass of the hemostat causes the hemostat and string to fall straight down. But be aware, some police consider hemostats drug paraphernalia. They'd lock me up and weld the jail door shut if they saw my collection of hemostats, alligator clips and laboratory glassware.

I ran into a problem Monday, time for the first lawn cutting of the year, trust me, at 73 I don't even use a riding mower because the vibration would kill my artificial knees, our landlords are a set of identical twins who love yardwork (as far as I'm concerned you could cover the front and back yards out to 50 feet from our home with a foot of small gravel and spray with an herbicide at regular intervals.) I did all the normal checks. The fuel was drained at the end of the season, from the fuel tank and carburetor bowl, the engine ran with fogging oil and the air filter cleaned, then the riding mower was placed in the detached garage. For the new season, the tires were checked and topped off, a new spark plug was installed, good gas used to fill the tank. The battery was on a float charger all winter. Turning the key to start caused the starter to crank with normal speed but no joy, not even a backfire. I used some ether (I'm lazy) and got a feeble backfire. Testing with a spark plug showed an arc the gap, but, at peak compression it takes a lot more voltage for the arc to form, how much more voltage, I'm not sure. But a mechanic told me "Up to 4 times." OK how on earth do I measure up to 20kV? The Leslie Corporation offers a nifty inline tester with a neon bulb with terminals on each end. The tester goes in series between the ignition coil output and spark plug hot terminal. If good, as in adequate, high voltage is present, the neon bulb will flash pretty brilliantly, if the high voltage is low, there might be a dim glow. The Leslie 20610 INLINE SPARK TESTER is available at Advance Auto or online. I went with Advance Auto because we decided time was more valuable then a few dollars. It was money well spent. Changed the ignition coil, PITA to get to, and presto, our landlords think I'm a genius. [Ha do I have them fooled or what?] We also used compressed air to blow debris out of the ventilation fins on the flywheel and generally clean the engine. The engine started instantly and ran perfectly. Looking back it is clear the ignition coil was dying over the last 2 or 3 summers because the engine runs smoother with a LOT more power. Our next joyful task will be to change the drive belts. They are a little frayed and I feel it's a lot better to change them when it's 50 then 90 with 80% RH. [Yippee I can't wait.]

OK I am not pushing the SDRplay line of SDR (software defined radios) but I received a PM that prompted this post. Oh I have no relationship with SDRplay then as a generally satisfied customer. I've owned several SDRplays and found then all adequate for general shortwave listening with the added benefit of reception up to 2GHz. There are people using SDRplay RSPxx receivers for police scanners, listening to aviation, listening to satellites, all sorts of VHF/UHF reception. I can't speak to VHF/UHF reception because I gave up listening to police and fire when they went to APCO25 digital. There are ways to receive APCO25 with the SDRplay RSPxx series, but, reading the "how to" it felt like a lot more trouble than it was worth to me. SDRplay bought the rights to a SDR control program and have made upgrades over the last decade or so to improve performance and to interface other software. https://www.sdrplay.com/sdruno/ Recently they offered a new program developed in house that offers vastly improved performance. https://www.sdrplay.com/sdrconnect/ From my perspective the fact this software only operates on Window 10/11 and that was a deal killer. https://www.sdrplay.com/docs/SDRconnect_Release_Notes.pdf However this program also supports the Raspberry Pi4, Pi5. https://www.sdrplay.com/sdrconnect-more-raspberry-pi-sdrplay-support/ Now I don't know anything about Raspberry or Linux but a friend's daughter does, she makes embedded control systems and this was a 10 minute project for her. My Raspberry Pi 5 is in a forced ventilation case. It supports a nice LCD screen, keyboard, mouse, and remote access/control via Ethernet. I use the RSPdx for MW DXing. I also use the RSP-1a as a panoramic adaptor, 'spectrum analyzer', for use with my tricked out Kenwood R-2000. I use the older SDRuno with a Windows 7 64 bit professional computer that also runs audio analytic software to figure out data formats. I also use a hardware FSK demodulator to drive software decoders that another friend wrote. [sorry he plans to sell them, so I can't share copies.] Sidebar as they said in the O.J. trial. I've been into shortwave listening since I was 12. I saw my first panoramic adaptor later that summer at the ham shack of a friend of my father and fell in love with the idea you could see RF on either side of where you were tuned. It took about a minute to realize I could ID SSB, CW, AM voice or music, and FSK. I barely understood FSK but the waveform was crystal clear on a spectral display. It only took 50ish years to have a spectral display. NOTE: While I've found the RSP family suitable for my needs, others may find them lacking. I strongly suggest anyone ready to dip their toes in the world of SDR to do their research. SDRs range from simple USB thumb drive sized units, with what might be considered marginal performance to SDRs like the Perseus or WinRadio, both offer world class performance with different approaches. I've played with both and both are amazing radios and come at a premium price. I'd start with something more modest, SDRplay or Airspy are probably the best, decent, introductory SDRs. I have minimal experience, an afternoon, with an Airspy SDR, I wasn't overly impressed but the band could have been dead that day. It happens. NOTE 2: The thumb drive SDRs are considered little more then toys by many. I have zero experience with them so I don't have an opinion.

We were discussing batteries a few weeks ago and I mentioned I used high value capacitors, AKA super capacitors, to replace the 3V lithium disk cell. I received an email asking for details. All of the receivers have a 5V rail, I used a 4 1N914 or 1n4148 small signal silicon diodes between the 5V rail and positive of the super capacitor to drop the voltage. The nominal voltage drop of a silicon diode is 0.7V, however under extremely low current this can drop to as low as 0.5V. It will vary from diode to diode even in the same family. I also included a 100 ohm resistor just in case, I like to always have current limiting. The V+ of the super capacitor was connected directly to the V+ memory backup. In my first installation I did things a bit different. I used a 1K resistor from V+ 5V to a string of 1n4148 diodes to give a "regulated" V+ between 2.5V to 2.9V. Memory keep alive in the R-2000 is 2V. I adopted the first version I described after some thought and experimentation with a R-2000 with a defective tuner optical pulse decoder on the main PCB that defied repair. You can tune the radio, it's just a royal PITA that can take an hour to tune to the desired frequency. I programmed in useful frequencies in all 10 channels and treat the radio as a fix tuned radio. I have WWV on 2.5/5/10/15, CHU on 7.850, and, US Global HF Network 4.7240, 8992.0 11.1750, 15.0160 and 11.2320 [interoperations with Canadian forces]. My super capacitors came from the factory keep alive PCB in Kenwood commercial radios, these PCBs were removed and trash after the PCB with all the programmed channels was installed. I've modified 10 Kenwood R-2000 general coverage receivers and 2 iCom IC-28A 2M amateur transceivers. I'll be modifying 3 more IC-28A in the near future. My super capacitors are 30 years old and are 4.?F, One R-2000 was not powered up for at least 4 years, probably 5 and half, all the memory channels were still there. Modern higher value super capacitors might have higher internal leakage. I've ordered some 100F 3V supercaps to experiment with. Supercapacitors have odd chemistry and I suspect they will last longer if they are kept biased at their operating voltage. I was given about 30 of the Kenwood keep alive boards, pulled the supercapacitors and they are on a 3V rail powered by my primary 12V ham radio power rail. They've probably been without power for maybe a week since I wired them to the 3V rail. My experience with the R-2000 that was powered off for at least 4 years suggests the chemistry is more robust then I initially suspected, but, the supercapacitors are in a dedicated plastic box and I see no reason to remove them from the power. [I'm too lazy to change some things without a good reason.] All of this came about because I couldn't find a replacement battery in Lexington and didn't want to wait for mail order, well that plus the memory back up cell in the R-2000 is soldered in, which means you have to remove all the very flimsy (cheap) connectors. I was initially going to mount a 2 AA battery holder on the rear of the R-2000 when I was given the Kenwood "keep alive" PCBs and decided to give a crazy idea a try. YMMV

Hello, I am looking for a differential feedback temprature regulator project which explains the theory best it could and give practical example in simulation. I am looking to design a very precise temprature regultor up to 1Kelvin. Is there some material of a project I could try to learn it? Thanks.

Hello, I am trying to understand the dinamics of the circuit taken from the youtube video. if we apply 2V DC the node 2 on the photo will be 1.4 (Vbe=0.6) The node 1 will expirience some voltage wich will be translated to the other PNP base. Could you describe how the regulating dinamics works here? Thanks. https://www.youtube.com/watch?v=nOOOAjoqCt8&list=PL4C141B35706AD19A&index=3 /g/electronics101/photo/296358/3896088?p=Created%2C%2C%2C20%2C2%2C0%2C0

A friend and fellow idiot sent me this link https://www.tesladownunder.com/WorldsBrightestBike.htm#BikeLights I am impressed and bow down to this guy. [and I'm glad I live nowhere close to him.] I gave up bicycles when I turned 16 for motorcycles with the logic "Now I can outrun cars...." They still don't see you, even at night with your headlight on drivers will cut you off with frightening regularity. I gave up on motorcycles after seeing two young riders get splatted by a 'queen mary' [any large car] while driving down the road. The bikers were in their lane driving sanely, the cars just ran them down. Anyway, the light from a Honda CA-77, CB-350, CB-360 wasn't anything to write home about and it was easy to outdrive your headlight, outdrive refers to driving faster than you can see ahead. [perhaps one shouldn't drive 80MPH on narrow back roads.....] Now this headlight would let you see far enough ahead to be useful....but blind the poor sod coming at you so he'd probably splat you. While I've kept my motorcycle endorsement, that's more because I'm stubborn then practical. There is no way I'd ride a motorcycle unless my life depended on it. I suspect my artificial knees would be most displeased. Consider the project as proof humans can do amazingly stupid things....I'm proud to be a member of such an inventive species. Worry about our long term survival chances, but what the heck, we can have fun in the mean time.

Previously wn4isx posted a link to: https://www.pa3fwm.nl/projects/miniwhip/ The reference refers to an improved version but there is no link to it. Does anyone know where I can find the improved version schematic? Any other suggestions? I remember seeing an article about installing an active antenna and avoiding extra local noise, but I do not remember where I saw it. Using SMT components is not a problem. Thanks Bertho

If you have projects that require data acquisition Ebay has several options but the gold standard would be Dataq. They offer a variety of data acquisition units, some are analog only, some feature analog and digital inputs. Their software is amazingly flexible and can allow you to view the data you've recorded in a variety of ways. Their most basic unit is about $50 but the drivers are for Windoze 10/11. It is possible to force an install under Windoze 7 64 bit professional but you risk breaking the install. I use Macrium Reflect disk imaging software so breaking an install takes about 6 minutes to boot the Reflect CD, snag the operational image and restore. There are many free disk imaging software packages out there, while I use Macrium Reflect, I won't pretend it is the best, but it was free and easy to learn to use. Being able to restore to a known good image makes it safe to try questionable software or configuration changes. I've broken ever version of Windows since Windows 3.11 For Work Groups. I went with the Dataq DI-1100 "Data Acquisition USB DAQ and Data Logger System, 12-bit, 20,000~40,000 Samples per second per channel. I actually have 4 DI-1100 in service. None has crashed. As of March 7, 2025 the DI-1100 costs $79 and comes with Dataq software. While the spec sheet says operation under Windows 7 will probably work, performance and unexpected errors are possible. I installed the drivers and software on a variety of HP PCs running Windows 7 64 bit professional. Your experience might be very different. I have an expensive data logger and analysis program that will only run under Windose, Wine and other Windose emulators for Linux don't work, yet. The software will load under Wine but doesn't properly work. So I'm stuck with Windows 7 64 bit professional for the foreseeable future. Dataq offers software for Linux but I have zero familiarly with Linux. The DI-1100 has 4 analog inputs with a +/10V range with a resolution of ±4.8 mV. [You can take a cheap sound card and bypass the input capacitor and use a resistive network to convert a cheap sound card to make a data acquisition unit. I've done this and it does work, might work pretty well, but is far less then optimal.]

Hello , I have designed a differentiator as shown below.The pulse in the simulation photos links below is 1ns which is 350MHz BW ,much higher then the BW of the AD8034 opamp.As you can see its working.How its possible? Why its differentiating the pulse although the opamp doesnt have such BW? Given the pulse what slew rate and what BW does the OPAMP need to have? https://eu.mouser.com/datasheet/2/609/AD8033_8034-1502231.pdf https://ibb.co/0VMSYCkQ https://ibb.co/tMkTLQt6 https://ibb.co/WpDF9Qch

No, I traded it to a WWII reenactor. My father bought the jeep new surplus in 1949. The state decided the original bill of sale was OK for licensing. The jeep ran fine in 1975 when Dad realized he wasn't going to drive it again. It had just over 400 miles on it. I suspect all the rubber would need to be changed. It was stored inside so the paint was like new. Fortunately there is a fairly large group of WWII jeep enthusiasts so parts won't be hard to locate. I 'learned' to drive in that jeep. Across cornfields that had been harvested. I'd just turned 9 and could barely reach the pedals and hang on to the steering wheel. And forget synchromesh transmissions, double clutching was an experience. Fortunately they were made for rough service. One thing about WWII jeeps is they have a high center of gravity and you can roll them in a heartbeat. I nearly managed it at 20MPH in fairly soft dirt when I turned too sharply.

The following items have been added to the Files area of the [email protected] group. /Temp/AD8034_differentiator.zip By: Andy <ai.egrps@...> Description: Examine the response of differentiator circuit that uses AD8034

OK I am weird, as a 3 year old (1954) I'd swipe my father's WWII MX-991/U flashlight. This is the standard right angle headed unit. I'd hide in closets, under the sink, under beds, in the small room the water heater sat in (under the stairs) and enjoy the light in the dark. Dad was frustrated, "D" cells weren't horribly expensive, but he grew tired of having to keep a supply. Mom took the view point "At least he's not using candles." A friend of Dad's worked for GE and gifted our family with early NiCad cells and a charger. Dad bought me my very own MX-991/U and I'd sit in the closet and listen to my "Boys Rocket Crystal Radio." My maternal grandfather gave me a very old Prango 2 "D" cell flashlight with a patent date of Sept 28, 1915. This unit uses a small silver plated "parabolic" reflector with a large glass lens. Thus began my collection of flashlights.....a collection continues to grow, I've never met a flashlight I didn't like. All of this is of historic interest and perhaps offers a view into my somewhat odd psyche, but what on earth does it have to do with Electronics 101. I could go into the vibrator powered electroluminescent light my dad built for me, or how my uncle replaced the vibrator with a pair of germanium power transistors, or how I made my first LED flashlight, it used red and green LEDs and either or both could be enabled, but I won't. [And for you with dirty minds.... https://en.wikipedia.org/wiki/Vibrator_(electronic)] Your portable electronic gear operates from batteries, unless you have a hand held generator or can operate off PV cells in direct sunlight. A friend gave me an interesting book. This book is almost mandatory for those of us who operate equipment from batteries Batteries in a Portable World: A Handbook on Rechargeable Batteries for Non-Engineers, Fourth Edition It is available at Amazon (and at the ARRL), it is a bit expensive at about $30. I still distrust secondary (rechargeable) lithium batteries, but they are a factor of modern life and, unless I wish to give up my cellphone, laptop PC, portable equipment, I have no choice but to learn to live with the !@#% things. The book starts out with the basics of batteries and might appear too basic for a serious hobbyist, but it gets down to brass tacks with reasonably detailed information on many different types of batteries, their strengths and weaknesses. And all batteries have both.

I have a Lorex wireless security system that uses it's own receiver for the outdoor wireless cameras. I just recently had another camera appear to fail but I can "pair" it with the receiver if I am within about 5 feet of it. Then as I move the camera away it loses connection. I replaced it with a new spare camera and problem solved. My question is can the camera possibly be repaired by me and what is the possibility it is just a bad capacitor or some other common component that would cause the limited range? I haven't opened it up yet but I just wanted to know if it is beyond repair or possibly fixable? Thanks

On Tue, Mar 4, 2025 at 08:37 AM, wn4isx wrote: Normal digital cameras are moderately sensitive to IR, ... I wonder if that's true of all of them. It probably is. Photons are photons. I know my first digital almost-SLR from 20+ years ago could, and I considered having the modification done to it. I love IR photography, but never experimented with it. I'm afraid it might become a "fad" that loses its appeal after a few hundred IR photos. The camera has a xenon flash that produces near zero IR. I have to illuminate an object with an array of IR LEDs. Can't you just use the built-in flash? Or did the camera's modification add an IR-only filter to the lens, making it insensitive to visible light? Andy

Dave <theschemer@...> added the photo album Lorex Wifi Camera : An image of the circuit board of my Lorex Wifi security camera that has lost it's effective range. The following photos have been uploaded to the Lorex Wifi Camera photo album of the [email protected] group. Wifi Camera.jpg By: Dave <theschemer@...>