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I've added a folder "Diode Commutation EMI" that explain the causes of diode commutation EMI and steps to mitigate it. There are other solutions today, special diodes with controlled turn off characteristics exist, There are soft turn off diodes, and, oddly enough, fast recovery diodes. I suspect there are others but those are the only two I have any experience with. The "MicroSemi 302 Rectifier Reverse Switching Performance EMI" is extremely detailed. I wish I'd had this paper in 1974.

Hello , I am assembling the bits and peaces of what I learned and trying to implement them into my mixer shown in the link below. there is the -174+10log10(BW) of the component my mixer is 10GHZ so its -174+100=-74 also the is conversion loss which affects the noise level. The harder thing for me to understand is the modulation affects because we can put unwanted spurs into our working band which could also ruin the SNR. Is there some mathmatical example I could use to assmeble all these factors together? https://markimicrowave.com/products/microstrip/mixers/m1-0818ne-1/datasheet/ Thanks.

When a member of our shortwave listener club showed me a PA0RDT active E-Probe antenna I almost giggled, being polite I didn't giggle. However I thought "Well PT Barnum was right...one is born every minute." Then we mounted the antenna and gave it a test swirl. And I was stunned. I won't bother listing the details of the PA0RDT Mini Whip, plans are all over the net, http://www.kiwisdr.com/docs/pa0rdt_whip.pdf This is one interesting variant https://www.pa3fwm.nl/projects/miniwhip/ A good overview https://web.archive.org/web/20230722120107/https://www.g8jnj.net/activeantennas.htm Note: It is critical to understand how an E-Field probe antenna works! It must be installed properly or it will perform badly. Properly is a bit complicated but easier then erecting a 'real SW antenna" [to mean a 100 foot wire antenna at least 30 feet off the ground.[ <especially when you are 73> All E-Field Probe antennas are a compromise but have their place in the grand scheme of things. I have several, one optimised for 'audio' [whistlers] through ELF, one for ELF to LF, one for LF to 30MHz, although I m not interested in much above 20MHz. 11Meters from truckers is a good way to test any antenna. Prepare to be frustrated but E-Field Probe antennas do have their place and can offer surprising reception and will also drive you crazy getting there.

I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRTs at my parent's home. The new owners called my sister and told her they found a box of "electrical junk" under the eves. I went over, collected the boxes, thanked them and wondered what the heck I was going to do with 5CP1s? Then I remembered my ham radio RTTY (radio teletype) enthusiast who uses a CRT to tune for best reception. This guy is old school, mechanical RTTY terminals, etc. He bought an Owon AS-201 "retro" scope. This is a accurate review, roses and warts. https://chinese-electronics-products-tested.blogspot.com/p/as201-benchtop-oscilloscope-tested.html My friend wasn't happy with the AS-201, I thought it was nice when I checked it out, sort of primitive, but the X/Y offers excellent Lissajous Pattern display. I've had a fondness for Lissajous display since I made my first 'scope from a BW TV when I was 12. I pulled the deflection yoke, replaced it with one that fit, I had no idea about impedances, fed the output of my stereo to the H/V and the weird pattern mesmerized me. So I called him and explained "I have 5 WWII surplus CRTs... wanna trade?" I'm pretty sure he broke the speed limit getting here, so I'm not the proud, if doubtful, owner of an Owon AS-201. It really is a nice, basic, emphasis on basic, 'scope. FWIW, I strongly suggest anyone considering the Owon AS-201 think it over, for a few dollars more you can get a modern DSO with many more, better, options. Since my Owon AS-201 is basically "found on the side of the road" I got a heck of a deal. He who dies with the most test equipment.... wasted a lot of money.

All sorts of stuff: https://mysite.du.edu/~etuttle/electron/elecindx.htm -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

86164.0905 seconds (23 h 56 min 4.0905 s or 23.9344696 h). Another way to understand this difference is to notice that, relative to the stars, as viewed from Earth, the position of the Sun at the same time each day appears to move around Earth once per year. A year has about 365.24 solar days but 366.24 sidereal days. Therefore, there is one fewer solar day per year than there are sidereal days, similar to an observation of the coin rotation paradox.[5] This makes a sidereal day approximately 365.24/366.24? times the length of the 24-hour solar day. https://adsabs.harvard.edu/full/1984IAPPP..17...55D Pages 55 ~ 61 I received an email asking "What is sidereal time and where is it used?" And "How do you derive it from 60Hz?" Wiki has a fairly good article on sidereal time. Sidereal time is used by astronomers. There are special motorized drives that change the azimuth (degrees north-south) and elevation (height) to keep a star centered in a telescope Any sane person uses a app for their Android or iPhone. But there are special people like My Crazy Cousin who lives north of Santa Fe who is an advanced amateur astronomer. Anyway My Crazy Cousin wanted a dual display clock, one display would show Mountain Standard Time, the other Sidereal time, both synched to WWV. I happen to have some unused National Semiconductor LSI MM5314 single IC clock chips. I used green 7 segment LEDs for the MST and red 7 segment LEDs for the Sidereal. I used an inexpensive precision 10MHz canned TTL oscillator with internal heater. She upgraded to a ~$150 GPS disciplined oscillator with a 10MHz output. I used a PIC programmed with magic code to convert 10MHz to 60MHz. http://leapsecond.com/pic/ http://leapsecond.com/pic/picdiv-list.htm scroll down to pd60.asm:; PD60 -- PIC "4-pin" frequency divider (10 MHz to 60 Hz) You feed 10MHz into the PIC and get 60Hz out, the accuracy of the 60Hz depends on the accuracy of the input 10MHz. Then open https://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1984IAPPP..17...55D&defaultprint=YES&filetype=.pdf And you see one way way to modify 60Hz to feed "sidereal 60Hz" to a LSI clock chip to display sidereal time. I used the same logic but with CMOS chips. Now if the Leapsecond.com only had a 10MHz to "60Hz Sidereal"..... Now as I said at the beginning, any sane person would use an android device, perhaps an older tablet for a nice large display....but My Crazy Cousins "observatory" is in a marginal cellphone coverage so she maybe she isn't so crazy. [She also happens to be my favorite cousin. A really nice if somewhat dingbatty person.] My personal GTM/EST/Sidereal clock uses 3 MN5314, on for each time zone and uses the chip enable pin to turn on the desired time zone. Of course mine was built from 1976 through 1980 in stages. I came up with a logic circuit using 74LS chips that achieved the same function. I replaced my 74LS design with the new CMOS. Unless you are an astronomer, or total geek, you will never need sidereal time, but this is one 'easy' way to obtain it. Of course she could simply have spent ~$200 at https://brgprecision.com/products/stand_alone_clocks/sidereal.php Note 1: I've never actually used the Sidereal function, the only really clear nights in Kentucky suitable for astronomy are when there are no clouds and it's -10...and I'll be inside where it is warm and either asleep in our bed or listening to shortwave. Note 2: The CMOS 7555 are a Xitch to get working properly! Note 3: I saw a scheme in a British or German electronic hobbyist magazine that used logic to switch the 50/60Hz input from 60 to 50 every so many cycles to obtain sidereal time. It's been over 50 years I don't recall the circuit. Note 4: For a really hard way to get regular and sidereal time https://www.worldradiohistory.com/UK/Practical-Electronics/80s/Practical-Electronics-1981-10.pdf Note: 5: It should be possible to use the leapsecond.com 10MHz to sidereal 1 pps to drive one of those cheap analog clocks. They have a 32?kHz crystal, "IC" to produce 1 PPS, it'd require some experimentation but it should work. Since M

Amazon offers: 10K Temperature Sensor Probe https://www.amazon.com/DROK-Waterproof-Temperature-Thermistor-Transimitter/dp/B01MR37GOQ I found one even cheaper on TEMU. The WTESKE Manual says: Type of temperature probe R25 = 10K ohms +/-1% B25/85=3435K+/-1% It is a two-wire probe. Before ordering, I thought it might be prudent to check to see if the controller had been damaged when the original probe melted. When the probe is removed, the display blanks out - Open Circuit. So, it would appear that some resistance is required for the display to indicate the current temperature. Question: What value of resistor might be needed to fool the controller into thinking there was a working R25 = 10K ohms +/-1% sensor installed? -- G.T.

There is a PI controller with certain AC behavior. I need to use this PI controller in order to drive a coil (current controlled oscillator) of 1.5 ?H inductance. For DC behavior at 10 mV input I need 50 mA current on the coil at most. PI controller has proportional and integrator property. How can I convert this behavior into a driver circuit? /g/electronics101/photo/296358/3878514?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3878513?p=Created%2C%2C%2C20%2C2%2C0%2C0

I am working on a Sabre Flashlight/Tazer combination. The LED has shorted but that is not the reason for this post. The charging circuit is very simple. The line voltage goes through a 684nFd cap to one side of a diode bridge rectifier. The other side of the bridge is connected to the other side of the line. The output of the bridge goes directly to a 4 pack N size Nicad battery pack. During the testing of the cap, the bridge lead to the cap broke. I have found replacements for the LED and bridge. I checked the value of the cap by using my function generator and scope to make a divider with a resistor and calculated the cap value. It calculates to 730 nFd. A little more than 20% low. My question has to do with the limiting of the bridge output. Since there is no voltage or current limit, what provides these two limits? Also should this cap be replaced due to its low value. There are no markings on the bridge other than the input sine wave and the output +/-. I will replace this with a 1A 1000V bridge. I have selected a 1 Watt 3.4 volt 20 mm heat sink LED since this was the original connection configuration. I am considering adding a 5 volt zener and resistor on the bridge output just to limit the bridge output. Any thoughts? Regards, Dan Kahn

OK, cannot include a PHOTO of the connection diagram on the 3PH 3/4HP motor in question. However it is rather a simple matrix diagram of nine points of connection: o o o o o o o o o They are labeled as follows: LOW VOLT CONN LINE-1-7 4 LINE-2-8 5 LINE-3-9 6 HIGH VOLT CONN LINE-1 7-4 LINE-2 8-5 LINE-3 9-6 So, for the LOW VOLTAGE (208V) the CENTER connections are jumpered (/) to those ar LEFT and, for the HIGH VOLTAGE (480V) the CENTER connections. The label states "TO REVERSE DIRECTION INTERCHANGE ANY TWO LINE LEADS" DO YOU KNOW if this means Connect LINE 1 to connector 2 and LINE 2 to connection 1 ? Or connection LINE 1 to connector 8 and LINE 2 to connector 7 (LOW VOLTAGE CONN) and connector 7 to 5 and connector 8 to 4 (HIGH VOLTAGE CONN)? NOTE: I cannot see the motor itself, nor the connectors - just the label. I am wondering if the LINE connections from a THREE PHASE SOURCE are numbered One, Two, & Three respectively indicating the direction / sequence of the phases such that swapping LINE 1 with LINE 2 would actually reverse the motor's direction. -- G.T.

The following items have been added to the Files area of the [email protected] group. /Sabre Zapper.pdf By: Dan Kahn <dankahn88@...> Description: Sabre Light/Zapper

Radio shack used to sell a board that they called a "Stereo Headphone Amplifier", which basically supported a pair of LM386 chips and supporting components. Some years back I found one at a hamfest for some really low price and snagged it. Built the board, put it in a minibox with both RCA and quarter-inch connectors at inputs and outputs, and found a suitable wall wart to power it with (also originally from Radio Shack, as it turns out). There were a few different options for things like gain, rolloff, etc. that you could configure on the board with jumpers, I elected to route these to mini toggle switches. Sometimes when I power this thing up it'll break out into oscillation. Turning the volume control all the way down will usually put a stop to that, but I'd like to find out what's going on and put a stop to it. *ALL* of the connectors are grounded to the box. Is it likely that this has something to do with it? Something I was reading not too long ago had input connectors isolated from the physical enclosure, due to "ground loops" or something like that. Could this be the cause? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

Hello , I tried to check the stability of the circuit by opening the feedback loop and placing the pertubation as shown below. How ever I made two plots Vf anole and Vf,Vin in AC responce and I get quite different result. What is the proper way to test feedback responce? Thanks. /g/electronics101/files/john233/classA_driver_new.asc /g/electronics101/photo/296358/3872575?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3872574?p=Created%2C%2C%2C20%2C2%2C0%2C0

I'm a sucker for test equipment, more so for good equipment at rock bottom prices. A friend dropped an inexpensive audio oscillator by for me to check out. https://www.akitika.com/1kHzOscillator.html#:~:text=Distortion%20is%20very%20low%2C%20typically,only%202nd%20harmonic%20is%20visible.) This oscillator has a claimed distortion of 2 parts per million (0.0002%). I only have access to test equipment that can measure down to 0.001% and this oscillator's distortion was lost in the noise floor of the test equipment. The frequency was slightly off, well within specs but 1002.31Hz. At $89 this represents an amazing value. Yes you can download their assembly manual and "roll your own" but I doubt you can achieve the performance of this unit. Part of their magic is their PCB layout and hand selecting the frequency determining devices. It isn't worth my time and energy to try and copy their PCB and locate accurate parts. I'm well know as a cheapskate and I ordered one.

I was given this little thing a while back, haven't done anything with it yet... There's this board, no particular identifying marks on just what it is. The oddest BNC I've ever seen on top, some switches down the left side that seem to be for selecting sensitivity and coupling, some DC input connectors on the top to power the thing, five buttons labeled OK, +, -, SEL, and RESET. A couple of pin headers and a USB micro connector on the bottom. A plug-in board labeled "2.4" TFT LCD. Two bits of paper came with it. One is labeled Oscilloscope DIY Kit User Manual but it seems to be assembly instructions. This bears the numbers 138803K and 13804K, no indication as to which unit I have here. The other paper has "How to Use" calling out the "Display and Controls". And some stuff about "probe calibration". On the back of that one are schematics that are barely readable. With a magnifying glass I see them showing power input as "9.39V". (!) Apparently some of this thing runs at 3.3V also. There's no case, though I'm told that one is available. Not told where, though. Have any of you guys run across anything like this? I'm a little dubious as to how useful this thing might turn out to be, haven't yet gotten around to digging out an appropriate wall wart to power it up... -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

If you are only interested in looking at audio on an oscilloscope, one decent method is to use a "high quality" USB audio interface. The Behringer UMC202HD is a decent unit that can be found at several music stores for around $100. Behringer enjoys a mixed reputation, apparently if you get a good unit they will work fine "forever." My three have been in nearly daily services for 4 years now. They are used as the analog to digital converter as a test instrument and to feed AF into a PC for audio analysis/decoding on a shortwave radio and one is used as an actual musical instrument input device. This circuit is used for the oscilloscope input conditioning. PC Oscilloscope Interface https://sound-au.com/project154.htm And these circuits are used for radio to PC, PC to radio PC To PA System Interface https://sound-au.com/project133.htm I used parts I had on hand so my circuits are slightly different. We use similar circuits to feed PC to/from our church's PA system and I carry a pair with my laptop just in case I find myself pressed into service as PA source or recorder. The PC to PA system interface will also function as a basic PC oscilloscope interface. For those who wish to study audio distortion, Mr. Elliot has some interesting, and downright weird, techniques. Intermodulation - Something 'New' To Ponder https://sound-au.com/articles/intermodulation.htm#s4 And Distortion Measurement System https://sound-au.com/project232.htm One can get by with a less then stellar USB AF device. Some well respected AF amplifiers show some surprising weaknesses when tested this way.

Hello, I have built a system shown below by the attached article.Its a frequency locked loop. basicky I am using a YIG as VCO to tune it exactly to the cavity resonator. The phase and amplitude of the resonance shown below. The mixer acts as a frequency discriminator by the behavior in photo 3. So if we input a tone at some frequency and look what IF (error voltage) we get at point B as shown in photo 4 and 5 . The main problem I have is the YIG VCO. The YIG has two coils which we tune. A large coil call "tune" and a small coil called FM. The large "tune" coil is being fed near the resonance area,while the smaller FM coil is the coil I use to tune the error of the mixer IF (frequency discriminator) which compares the signal coming from the cavity resonator and the signal coming from the YIG. The second coil is FM coil: 1.5uH inductance and 1Ohm resistance FM coil. sensitivity 400Khz/mA The main problem is that I am tuning the error using the FM coil while the tune coil (which is biased by constant voltage) is not in the feedback fixing mechanism I only have the FM coil to compensate for the gap between the YIG and cavity signals. I was told to use a PI controller(between the IF output and YIG input )to compensate fro the tune drifting. Is there some strategy on how what parameters the PI controller should have to compensate for the exteral frequency drifting caused by the tune coil? Thanks. /g/electronics101/files/john233/High_spectral_purity_microwave_oscillator_design_using_conventional_air-dielectric_cavity%20%284%29.pdf /g/electronics101/photo/296358/3871687?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871686?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871685?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871684?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871683?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3871682?p=Created%2C%2C%2C20%2C2%2C0%2C0

Been playing with various chinese-originated latching relay solutions from Amazon. Most are 'overly optimistic' about capabilities. Very 'overly optimistic'. Otherwise the rest have issues operating in environment with heavy canbus, Bluetooth, pwm alternator, 2M xceiver, and brushed engine / HVAC fans. Reaching way back in my mind, I seem to remember JK flip flops toggling output when strobed if J&K are tied high. Maybe it wasn't JK, but another type? Important points being that outputs are low upon turn on, and stroking with momentary (debounced) switch (high input). I am thinking that can tie outputs to darlington driver array, like ULN2803 or similar. Up to 1/2A current, 50vdc max, designed for inductive loads. Haven't found any information on temperature control yet. Not sure if I am reinventing the wheel. I do know that relays / contractors that utilize magnets for latch hold are probitive physically and way overkill. Incidentally, relay outputs will be controlling multiple isolated power supplies. Need around 16ch of mixed outputs. Suggestions or alternatives if I am on wrong path? Tomorrow I will be trying to find 32/64 bit versions of LTSpice (or similar) as my 486DX4 based PC (500MB drive and 8MB Ram!) 16/32bit machine died during Hurricane Beryl. ~SD

Hello,I have the following old mixer called TXF-18075 which I want to test for saturation and power levels in down converting mode. I dont have any datasheet only this brief table I found.Unlike amplifier A mixer needs two input powers the RF and LO. How can I see In my lab two things: 1.What is the needed LO power? 2. How can I see mixer saturation using lab equipment? Thanks. /g/electronics101/photo/296358/3870599?p=Created%2C%2C%2C20%2C2%2C0%2C0

Hello: I am Ken Gordon, am now 82 years old, and have been involved in electronics since I was 13 years old in 1956. So, recently I have been involved in "Elmer-ing" a good friend who is not particularly adept at electronics. I have been helping him get his ham station operable on digital modes. He bought a new Acer laptop to use for these modes. While trying to get Fldigi installed, we discovered that his Acer laptop's USB ports' two data lines are reversed from all others we have dealt with up to this time: i.e. Data - (minus) and Data + (plus) are "reversed" in his new machine. This, apparenty, doesn't matter when those lines are used for USB devices such as a mouse or a USB powered CD drive, but that DOES matter when those data lines are used to pass audio to/from the computer to the digital interface (in this case either a SignaLink or a DRA device). I thought it might be easiest for me to make him a short jumper cable out of a short USB extension cable by cutting it, and "cross-wiring" those two data lines. However, upon opening the cable, I find not 4 (or 5) wires, but a total of 11, 3 of which are obviously grounds. I have not yet been able to "ohm-out" the wires vs connections since I must make a needle-point adapter for my VOM, but in the meantime, here are the wire colors. First, separate black, white, green and red. These should be the standard + and - 5 V and Data + and Data - But there are two "bundles" of other wires, These "bundles" contain a slim bare wire and two other thinner wires, pink and purple in one "bundle" and blue and yellow in the other. Might anyone here have a clue as to what these are, or how they are wired? Ken Gordon W7EKB Virus-free.www.avast.com