开云体育

You should not delete a message (or an entire thread) just because you say it is off-topic, while at the same time saying that it is on-topic and appropriate. If it was really worth posting here in the first place, it should remain. Did we not read a while back that you would not deleting your messages? How's that going? Frankly, I am tired of this nonsense. Andy

Hello , I have built a PLL system based on the following article. I have designed the amplifier to have some input voltage current output behavior. but in the lab I sat that when i plug the the input I get oscilations at the output. what could cause the situation? 3d PDF Layout and lab photos are attached. Thanks. /g/electronics101/files/john233/High_spectral_purity_microwave_oscillator_design_using_conventional_air-dielectric_cavity%20%284%29.pdf /g/electronics101/photo/296358/3862595?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3862596?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3862597?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3862598?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3862599?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3862600?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3862601?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/files/john233/layout_new_amp_updated3.pdf

I've been dragooned to help a friend I've known since the second grade. Jimmy designs and builds ultra high end audio systems, he builds everything up to the speakers. Recently he's ran into some odd problems where "identical" transistors behave differently in high end audio. He purchases directly from the manufacturer so the chances of counterfeits is pretty low. It's been a life time [1968~1973] since I designed any serious audio amps. I realized my talents lay elsewhere and it was a better value to trade money for decent amps then spend nearly unlimited hours to obtain similar results. Note: I do not consider myself an audiophile, I damaged my hearing riding a motorcycle for 35 years and had tinnitus as a young child. Sooo, I'm refamiliarizing myself with the issues of high end audio design, theory and reality. No amplifier is perfect, they all have artifacts. One thing that is very different today from way back when is moderate priced USB audio I/O 'cards' allow meaningful FFT analysis that actually matches reality, within limits. I downloaded this book to start with.... Bob Metzler - Audio Measurement Handbook https://convexoptimization.com/TOOLS/Metzler.pdf While copyrighted it appears in quiet a few respectable locations, I'm guessing the author has waived copyright issues. Rod Elliot of ESP audio has quite a few articles on design and measurement of distortion. https://sound-au.com/articles/distortion.htm https://sound-au.com/articles/intermodulation.htm#ref https://sound-au.com/articles/intermodulation.htm https://sound-au.com/project52.htm Uses a sound card to measure distortion https://sound-au.com/project232.htm Perhaps the single most useful trick shown by Mr. Elliot is his "distortion adder." It allows sanity checks, which, when dealing with audio distortion is necessary. It is way too easy ending up chasing your tail like a puppy or kitten. That's why I gave up on amplifier design in 1973. A quasi-comp Sansui AU-555A sounded much better then my best efforts at about 1/2 the cost in material and 1/gazillionth the wasted time. I could have collected sodapop bottle along the highway, turned them in for the deposit and been time ahead. I'd reached a point where I'd lost confidence in my ability to measure differences in slight design variations. One important issue, I've been playing with several USB sound cards for several years and realizee "The 5V power rail in most USB systems simply suck!" Modify your USB cable and add your own 5V power supply. I went with a LM7805 with the standard design with an added 1uF tantalum (I hate and distrust tantalums but they have the best filtering capacity for size and a 100uF and 1000uF on the 5V out. I'm not convinced the added capacitors were worthwhile but the PCB I used had the pads for them so I decided to toss them in. [Be certain to tie your 5V power supply V-/ground to PC USB V-/ground! I spent an hour late one night wondering "Why doesn't this damn thing work!"] The residual noise floor was just under 10dB lower with the external supply versus the laptop USB 5V power. You mileage will vary because every maker of USB almost certainly has different noise issues.. I suspect Jimmy is running into the hard wall of physics, where each device is inherently different even if made at the same time. This is something I have no idea how to verify. They don't call it the bleeding edge of technology for nothing. Oh, and don't bother trying to test the modulator in your SSB/AM/FM ham rig, they all suck.

Found a few low voltage isolated buck converters on Amazon, 12/24vdc in, 12/5vdc out. While I could make those work, the cost is high. I need something that is able to deliver 12vdc, at least 100w. Best solution I have found is: Orion-Tr 12/12-9 (110 W) Orion-Tr 12/24-5 (120 W) Both offer 200v 'galvanic' isolation (vs intrinsic?) and should work. Cost is higher at $64 ea, with needed qty of 4. Ultimately the outputs will be connected to individual LFP cells that are already connected 4s. Basically Top charging. Haven't been able to use 'traditional' LFP batteries as I would be pulling ~180A short burst intermittently. Basically is 2nd Battery used only for starting an engine. Current solution is using 12vdc to 120vdc converter, and feeding to an isolated smps that is rated for DC on AC inputs. Repeat 4 times. Lots of underhood space used. While above is very doable, a 500w inverter feeding power supply then LFP single cell chargers through isolation transformers should work as well. Or find isolated versions of the LFP cell chargers. Anyone have suggestions on isolated converters, or isolated single cell LFP charger? My searches at Amazon, Digikey, Mouser, Allied have been kind of dismal. And in case you are wondering: Yes, this abomination would comprise several loads switched by latching relays. ~SD

hi all,i have just ordered one of these counters,are they any good for radio alignment lo and if stages et? https://www.aliexpress.com/item/1005007393827258.html?spm=a2g0o.order_list.order_list_main.5.21ef1802ekk16Shttps://www.aliexpress.com/item/1005007393827258.html?spm=a2g0o.order_list.order_list_main.5.21ef1802ekk16S

Hi all, I have just brought this psu,https://www.ebay.co.uk/itm/186801000648 its o-30v 0-1a,its made of discrete components with no ic's, its transfo has a center tap then +50v,+40v/-50v+-40v taps with a seperate 6.3v winding , the main voltage pot is a 1k with just the center and one outer leg used,its 1k at max volts,would it be possible to mod this for say 2amps and 70 ish volts output? would anyone have any ideas ie schematics etc,or an explanation of its circcuit topolagy,it has a wirewound resistor of 1 ohm,i assume that is a current sense resistor,i have uploaded some pics of it in the photos section called my psu,cheers in advance 73 Paul de m3vuv.

A friend has a production company with an audio studio. He switched from reel to reel tape to hard files in the mid 1990s. He called me in panic yesterday when he couldn't access one of his original archival hard files. I went over and was able to "wake the drive" by tapping the hard file with the handle of a large screwdriver, I'd have used a plastic mallet if I'd had one. NOTE: Do not do this until every other trick has been tried! Some hard files have glass platters and I had to tap pretty damn hard and could easily have shattered glass platters. [How hard? Like driving a nail in concrete.] We were able to copy all the audio to a new drive but that raised a question... I've always said there are two types of hard files, those that have died and those that will. I warned him about the various ways hard files die, CD/DVD ROM rot, how audio tape can have the binder (glue) that holds the magnetic material (fancy rust) and become unusable. "Other then clay tablets with cuneiform, all media degrades over time." He also collects "tombstones". Not literally, he's a member of a local history group and they make paper tracings of the information on tombstones. I asked "How many are barely legible?" "Quite a few of the older ones." I have no idea what he's going to do, he's 78, well off financially and may decide to retire. That would be suboptimal for former clients but he is facing a nightmare in time alone to back up all the hard files. Since each client's data is on their hard file(s), I suggested he contact them and give them the hard files with the suggestion "Back this up today!" Most of us don't give much thought to preservation of archival data but maybe we should. Here are two links that look at the issue https://arstechnica.com/gadgets/2024/09/music-industrys-1990s-hard-drives-like-all-hdds-are-dying/ https://arstechnica.com/features/2005/02/hdfailure/ NOTE: I've avoided Apple products and have no idea what magic key strokes he's describing...and I'm happy to remain ignorant. Several friends have contacted me over the last 20 years with I-Omega zip drives with "Data I have to recover!" I wished them luck and told them I have zero experience with zip drives and intend to keep it that way. I have had CD-R/DVD-R fail and 1 early commercial CD music disk lose 2 tracks. I was a bit irritated but found a new CD and tossed the old one. I have a large "archive." [if such a mess of unorganized data can qualify as an archive.] I haven't lost a drive, yet. I'm in the process of pulling the most important data to new hard drives. Since I have several Exabytes of data...yea it's a lot of unfun. I inherited 3 NTSC digital video editing systems after helping upgrade a local production house upgrade to digital. Digital video editing requires very fast RAID hard files, older hard files that were perfect for NTSC won't work. Not needing any video editing systems, I salvaged the drives and sold the stripped carcasses. The 'unlimited' storage allowed me to save anything online I found the least bit interesting. I'm having a difficult time separating the wheat from the chaff. What to save and what to let nature take her course.... or just erase it all...

The following items have been added to the Files area of the [email protected] group. /counter info..pdf By: paul larner <quadzillatech@...> Description: more info on chinese 8 digit counter moduals inc schematics.

The following items have been added to the Files area of the [email protected] group. /aliexpress frequency counter modual manual+ schematic/PLJ-8LED counter.png /aliexpress frequency counter modual manual+ schematic/PLJ-8LED_Manual_Translation_EN.pdf By: paul larner <quadzillatech@...>

Hi all, I have a cheapo PLJ-8LEDfrequency counter modual,it works ok but for anything above hf needs a lot more drive,can anyone recomend or link to a schematic for a wideband buffer and amplifier to make this work upto uhf?,thanks in advance,i have added the manual and schematic to the files section.

Is there software that can convert schematics to a circuit board design? I have some schematics that I want to see if I can make a circuit board from (perhaps to 'recreate' the device that schematics are of).

The following items have been added to the Files area of the [email protected] group. /PLJ-8LED counter.png By: paul larner <quadzillatech@...> Description: counter schematic

This will be my last post on non-LED semiconductors emitting light. First, all of the forward biased semiconductors I tested emitted light. The glass cased silicon diodes were the easiest to verify, I chopped the tops of several TO-3 and TO-5 transistors. All of the emitted light required a night vision (starlight) scope to see. 4th vision nightvision scopes have between 25,000-110,000 gain, the exact gain figures are apparantly restricted by ITAR [International Traffic in Arms Regulations]. However reverse biased semiconductor junctions are a different story. I'll admit I was pleasantly surprised.... A friend gave me this link. Interesting to be sure but I doubt it's practical. http://cappels.org/dproj/Avalanche_Photogenerator/Avalanche_Breakdown_Photoemission_and_the_Photoelectric_Effect_in_Bipolar_Transistors.html And it might be worthwhile to follow the links here https://www.eevblog.com/forum/projects/transistors-die-pictures/ This image is fascinating and I was able to come very close image with a 1980s 2N2222 with the top removed. https://www.richis-lab.de/Bipolar02.htm This light is clearly visible in a dark room. I sacrificed 3 2N3055s. These were older RCA units with excessive leakage. All 3 emitted nice light when the collector to base junction was reverse biased to break down. Note: Limit breakdown current to a few mA. This has been an interesting, if relatively useless experiment.

Hello , I have an intresting phenomena when I am trying to lock my PLL by the system shown below.(from the attached article. My error voltage which is IF of a mixer gets amplified and the amplified signal goes into YIG(VCO) When the phase difference voltage is low and rippling as shown in photo 1, then I see the VCO going crazy back and forth changing the frequency as shown in photo 2. However when I turn the phase shifter and the error voltage is getting higher then I get straight line error shape and a single tone(as shown in the attached video in the link) I wonder about two things : 1.When I put big phase shift then IF signal voltage also is high. High IF signal goes into my amplifier and its getting comppressed (final amount of current going into YIG) So thats in turn creates a final amount of shift in the VCO so thats why i get a single tone. But error signal after the feedback is a straight line. What is the meaning of that? 2. My VCO needs to be connected as negative feedback. Does it act like the feedback is negative in my system? Thanks. /g/electronics101/photo/296358/3860748?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3860749?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/photo/296358/3860750?p=Created%2C%2C%2C20%2C2%2C0%2C0 /g/electronics101/files/john233/High_spectral_purity_microwave_oscillator_design_using_conventional_air-dielectric_cavity.pdf Video link: https://technionmail-my.sharepoint.com/:v:/g/personal/yefimv_technion_ac_il/ES9y1VBxJVBAlNUUmKMyMT8BGzjR9Kd-cN36A6_6LWSdmg?e=duFpS5&nav=eyJyZWZlcnJhbEluZm8iOnsicmVmZXJyYWxBcHAiOiJTdHJlYW1XZWJBcHAiLCJyZWZlcnJhbFZpZXciOiJTaGFyZURpYWxvZy1MaW5rIiwicmVmZXJyYWxBcHBQbGF0Zm9ybSI6IldlYiIsInJlZmVycmFsTW9kZSI6InZpZXcifX0%3D

paul larner <quadzillatech@...> added the photo album my psu : my psu pics

We've had several requests over the last few years for LED flashers for model train enthusiasts. One problem with most LED flashers is the go from full off to full on whereas old style caboose, water tower, and crossing gate lights were incandescent and ramped up and down. If you look at brake lights on cars in traffic it is easy to see this effect, the LED brake lights come on instantly and the incandescent ramp up when turned on and down when turned off. I have no idea what degree of realism model train types want or can achieve. I remember with my model trains as a child I was unhappy with the 'acceleration curve,' you went from standstill to ~20MPH. And yes I know there are better controllers today. http://cappels.org/dproj/1.5V_Red_fader_blinker/1.5_volt_1970%27s_style_caboose_marker_flashing_led_light.html There is a short MOV you can download to see if the effect is what you want. [I stumbled on this by accident and can offer no advice.]

Right - new moderator off the rails! -- G.T.

I am an idiot. Yep, it is confirmed. I've spent a lot of spare time in the last 2 months getting a hi-impedance analog meter suitable for aligning a radio's intermediate frequency. And I have a perfectly good HP 400E AC voltmeter, response +/-10% full scale 10Hz to 10MHz. I've had this meter for 40+ years, use it several times a week to measure the audio, 10Hz to 20kHz, levels in various audio systems. And 2ish months ago I needed a high impedance analog meter, the 400E has an input impedance of 10 meg. And I never considered I could use this meter for aligning a 455kHz IF strip! Argh...before going to a lot of trouble searching for the proper piece of equipment ... stop and think about your task and what equipment you have. I could even have used my oscilloscope, but no I had to do it the hard way because I became fixated on "I need a high impedance, wide range, RF voltmeter." Well at least I now have a nice Simpson DVM with analog sub-meter and a nice Heathkit FET "VTVM" [their label, to me a VTVM has a vacuum tube] And I've learned an valuable, if embarrassing lesson. Can't wait to share this with the SWL club. They can use a good laugh.

I used SMC, sort of old school term for surface mount components. Here is a better description of various surface mount things... https://www.opledtw.com/blog/what-is-smd-smt-sma-smc/ What is SMD / SMA / SMT / SMC / SMP / SME? What’s the difference? I use SMC for all those tiny bits. Call the language police and have me arrested.

I've been working on a Simpson 460-3 DVM with analog sub-meter. There are 2 primary scales, .200V and 2.0V, all the higher voltages are attenuated to one of those. The zero and +/-2.0V was a breeze, the .200V has been a nightmare. Two controls interact. After switching the Vin bananas a few dozen times I decided enough and rigged a special 'calibration cable' with a 4PDT switch with gold/palladium contacts as a DPDT to reduce any contact resistance. To change from Vcal+ or - to the opposite means flipping the switch. I've got it so the V+ is 10.00V, and the V- 10.01, I'd prefer V- to be 10.00 but I'll accept what I've got. I obtained this meter because of the analog sub meter. Aligning RF stages is a challenge with a DVM, the analog meter is an ~3 inch wide and ~0.5 inch wide edge meter and very nice for peaking and nulling RF stages. My next project is assembling a Heathkit IM-28 VTVM. While labeled as a VTVM it is actually a FET and opamp meter. As I've noted before, I no longer use alkaline cells because of repeated leakage problems and use primary lithium. Lithium cells have a ~10 year life expectancy and don't leak. Can you drown in test equipment.