Re: Some observations on linear power supplies
On Wednesday 05 February 2025 04:45:28 pm wn4isx via groups.io wrote: And my 5th bone of contention is their overvoltage crowbar sucks, it was obsolete in 1960 and is prone to false firing and also failing to trip when there was an actual overvoltage.
That crowbar circuit in the referenced pdf didn't make a whole lot of sense to me. Not that I examined it that closely, it's approaching the limit for what I can see on this monitor. But do you need that much? To me a zener diode, a resistor and a cap giong from gate to ground, and an SCR should probably do it. Oh, and I'd put a fuse immediately preceding that circuit. Getting just a bit more involved maybe use one of those 431 parts, then you could trim it to the exact voltage that you wanted it to trigger at. How would you design one? -- 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
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Re: Some observations on linear power supplies
On Wednesday 05 February 2025 04:45:28 pm wn4isx via groups.io wrote: 2) Astron uses the uA723 regulator, a fine regulator even if it is 50 years old.
However Astron, like most users of the uA723 never read, or at least never understood, the original spec sheet requirements for feedback capacitor and ~1k series resistor to protect the current sense input. Leave that resistor out and you will pop a uA723 faster then you'd believe. This is based on personal experience with home made uA723 power supplies and Astrons at 2 jobs.
I last messed with the 723 somewhere in the early 1970s. I'm guessing that this was before the common 3-terminal regulator parts were pretty much everywhere. I have very little reason to consider using one these days, unless I'm missing something here. My salvage over the years has yielded me enough 7805 and 7812 parts (and lots of others) that I don't see me running out any time soon. While I suppose that there might be reasons to consider using the 723, none are coming to mind offhand. For higher currents I have a couple of switchers on hand, one 25 or 30A, the other one 10A. Both are adjusted to 13.8V. I'm seeing that pretty many places with ham radio stuff. I'm wondering if circuits that are calling for a nominal "12V" will be bothered by that 13.8V... For anything else, I have a whole mess of computer power supplies, both "AT" and "ATX" style, and a couple of large boxes full of wall warts, both AC and DC output and varying voltages. 3) Astron occasionally parallels silicon rectifiers. I believe that the circuit in the referenced pdf uses two sections of a bridge rectifier. Which still doesn't mean that they're gonna be identical, but... Now I can't remember if I've ever actually seen that done in a commercial product. I don't recall any instances. -- 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
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Re: Some observations on linear power supplies
Note 3 should read
Add a 0.01uF capacitor with a 27~33 ohm resistor in series across each power rectifier to minimize commutation EMI [radio noise].
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I have a nice PDF on diode commutation noise and somewhere I have a "story" by? production engineer about how he had to add the RC network to a power supply that had passed military EMI tests for years yet suddenly failed because the diode manufacturer had improved the diodes and they turned off faster, which produced serious EMI.
I know for a hard fact 1968 1N4004 are a lot slower then (most) modern 1N4004 because the silicon is purer and the PN junction area is "more perfect."
For most applications this isn't an added issue for radio power supplies even the 1968 1N4004 required the RC network to eliminate commutation EMI.
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FWIW and full disclosure, while I hold an extra class amateur and commerical radio engineer license [Formally known as the "First Class ticket", thank you FCC for cheapening my efforts] I am really a shortwave listener.
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Actually shortwave listener is a bit of a misnomer because I am interested in everything from 1,000Hz [whistlers[ to about 20MHz. I typically go for signals right at my local ambient RF noise floor and any added noise is a problem, so my power supplies must be as quite as I can get them.?
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At one point I used a R392/URR, portable 24V version of the famed R390A. and used 2 12V deep cycle marine lead acid batteries as my power supply. I'd float charge them when not in use. Eventually it became too much of a hassle dealing with acidic fumes and I was forced to learn how to build a RF quiet 120V to 24V DC power supply. It was an interesting and extremely frustrating process.
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In 1974 the idea a power diode could produce intense EMI was a confusing concept. There are brute force and elegant solutions to most engineering problems. My solution was brute force, an EE professor took me under his wing and taught me how to finesse my problem, his approach has helped with other EE problems.
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I am far far from a decent design engineer, I am painfully aware of the areas I'm weak in and don't hesitate to get help from other engineers who in turn come to me for those areas I am an "expert" in,
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Finesse requires you understand what is going on, clearly the engineers who designed the pedestrian bridge in Florida that collapsed couldn't even manage a brute force approach. While no one reading this is likely to design a bridge, please try to design and build projects that are safe.
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Some observations on linear power supplies
First I consider Astron power supplies to be over rated and exist only because "hams have always used them."
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I'm amazed [really more dismayed] they get decent reviews.
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There are too many deficiencies to list, so I'll only list 3
1) Astron uses Intermittent Commercial and Amateur Service (ICAS)? in their specs, if you are lucky you can find the Continuous Commercial Service (CCS) current, the CCS is typically about 60? to 70% and take the CCS rating with a huge block of salt. To begin with, to achieve CSS one must provide forced air across the heatsink, this won't help the power transformer, which can fail spectacularly.
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2) Astron uses the uA723 regulator, a fine regulator even if it is 50 years
old.
However Astron, like most users of the uA723 never read, or at least never understood, the original spec sheet requirements for feedback capacitor and ~1k series resistor to protect the current sense input. Leave that resistor out and you will pop a uA723 faster then you'd believe. This is based on personal experience with home made uA723 power supplies and Astrons at 2 jobs.
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3) Astron occasionally parallels silicon rectifiers.
This is such a bit no-no I ought to use 60 point font with flashing red.
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As an experiment, obtain two identical, by identical I mean 2 rectifiers from the same manufacturer with the same date code.
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Places a 1 ohm resistor in series with each, force 10A, ~5A through each, and measure the voltage drop across the diodes. They will NOT match. The diode with the lowest voltage drop will hog most of the current and can overheat. Buy a diode with a higher, the proper, current value.
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This is a link to a popular Astron linear power supply.
https://www.repeater-builder.com/astron/pdf/qst-2005-12-pg56-57-power-supply-analysis.pdf
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It is a litany of how to build a commercial product with a great return for near the absolute minimum skill and design quality but not a diagram for a power supply I'd consider acceptable.
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My 4th bone of contention is Astron uses way too low value for filter capacitor. I'd go with at least twice, probably 4 times.
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And my 5th bone of contention is their overvoltage crowbar sucks, it was obsolete in 1960 and is prone to false firing and also failing to trip when there was an actual overvoltage.
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A real world experiences, an Astron linear power supply overvoltage failed to trip and fried a 5K video effects unit,
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Note: The system existed when I was hired, I never saw the plans until the day the magic smoke escaped from the video effects unit. I had difficulty keeping my mouth shut and not screaming "What f-ing moron designed this system!" However after 40ish years working for idiots, I've learned to keep my mouth shut.
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My fault diagnosis, autopsy for what happened, led to an engineer suddenly leaving for greener pastures. I had a friend edit and basically rewrite my report so it didn't catch fire. It was still so brutal the agency legal department took me to task, I flatly stated I can prove every statement I made and feel free to fire me for telling the truth, "But I bet HR in Frankfort will disagree." They backed off. I've been called a pitbull with an attitude. I'll proudly accept that label when it comes the truth in any form..
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If you want a good linear power supply, look to Lambda for high end, 100% reliable and expect to pay premium, For generally reliable, especially if you add a decent overvoltage crowbar, look to ? linear power supplies.
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Bel has gone through several names changes, they were Condor, Power One, Power CA (or Power California).
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I've purchased several off Ebay and they all met original specs, even those 30 years old. The biggest weakness is the silicon heat sink compound dries out and the main filter capacitor can dry out.
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Condor, Power One, Power CA (or Power California) also to vastly overrate their power supplies, and will require force air ventilation!
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They use the chassis as the heat sink, no real heatsink with dedicated fins.
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Note 2: I only use switch mode power supplies for non critical loads/systems and only when they can't be replaced with linear power supplies. My first IBM (real IBM mother board) was a bare board, I built a linear power supply, a really bad, bad beyond belief, idea. There are reasons why PCs use SMPS. The heat from a linear power supply can warm a chilly room.
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Note 3: Oh yea, add a 0.01uF with a 27~33 ohm carbon comp resistor across each power diode to mitigate commutation EMI noise.
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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.
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I won't bother listing the details of the PA0RDT Mini Whip, plans are all over the net,
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This is one interesting variant
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A good overview
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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>
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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.
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
Re: "Honda stock electrics sucked almost as bad as Lucas."
I've never been able to understand the original stock Honda 350/360 charge system.
It appeared to be a SCR that shorted out the V+ after a selenium rectifier.
I replaced it with stud mount Si diodes and conventional linear regulator built with a germanium pass element to reduce Vf losses.
I'd loved to have had LED headlight, tail/brake lights and turn signals.
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You know the reason Brits drink warm beer?
Lucas made their refrigerators.
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I helped a friend restore a Triumph car, the electrics were Lucas. I learned "Rip out the entire electrical system and rebuild from the wiring up. I was 16 and it was the first time I realized "Oh damn! I don't have a clue....."
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The best thing I can say about Lucus is nothing I will ever own will have Lucus e;ectrics
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
On Tuesday 28 January 2025 05:21:55 pm wn4isx via groups.io wrote: I'm really a shortwave listener who happened to pick up his ham license.
An interesting read, that. I've been pretty lucky, the closest I've come to that kind of an encounter is the other end of the town where I lived before I moved over here. That, and one other occasion where one hit a few miles south of town and did a bunch of damage. Here in this valley there's not been very much of that sort of activity, and it's not been close by, until this past year. There was a "hog barn" in the back of the property, mostly used for storing a lot of stuff (not much of it mine). That got pretty well trashed in some high winds, and had to come down. There's been a new foundation poured and there are plans for a steel building going up there. That nightmare convinced me ham radio had a use. I rode a Honda CB350 with a modified electrical system. Honda stock electrics sucked almost as bad as Lucas. I'd never heard that, though I can't claim any real familiiarity with that sort of thing. Though of course I've heard about Lucas... Anyway, a ham friend loaned me a converted Motorola police HT to ham band, a CBer loaned me a Rat Shack CB, Got one of those, and I've never used it. Nothing on the air around here, not until you get over the mountain at least. I was into messing with CB for a while, and then I got online and that was the end of that. we ignored the FCC rules and I was the mobile messenger, I could get through places no car could. I can see how that would work. We had thousands of trees down on major roads minor roads were a nightmare.
I handled over a thousand health and welfare messages. At one point some years back we went up into the Hudson Valley in NY state, and I saw a lot of that kind of damage. Talking to one guy who lived there he said an ice storm was responsible for that. Someone squealed to the FCC and was told PICON (public need, convenience or necessity) covered our actions, I received a nice letter from the FCC suggesting "Get your ham license."? There wasn't any threat but I knew Morse code, was an EE student, had been messing with electronics for years, so the theory was easy. I received my license 3 weeks later. I would have gotten mine years earlier if it weren't for the code requirement, I never did learn Morse. It's even on my list, and I actually went and bought a key at some hamfest a while back. A CPO is on my list of stuff to get to one of these days. I'm 73 and get your issues about erecting antennas. Fortunately our landlords are healthy 20ish year old girls and are quite willing to help me erect antennas. Not here. I suppose I could find some help with that once I get motivated to actually do something about it. Perhaps when the weather gets warmer... One reason I did the great toss out was my age, there isn't anyway I'd ever use ha;f the stuff, hell I'd bust a gut lifting some of it, life is so much simpler since I got rid of 99% of the dross. I've had some thoughts along those lines lately too. Scrapping stuff out, looking at what piles of it there already are, and thiinking how I'm never gonna use all of that stuff... -- 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
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
I'm really a shortwave listener who happened to pick up his ham license.
That nightmare convinced me ham radio had a use. I rode a Honda CB350 with a modified electrical system. Honda stock electrics sucked almost as bad as Lucas.
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Anyway, a ham friend loaned me a converted Motorola police HT to ham band, a CBer loaned me a Rat Shack CB, we ignored the FCC rules and I was the mobile messenger, I could get through places no car could. We had thousands of trees down on major roads minor roads were a nightmare.
I handled over a thousand health and welfare messages.
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Someone squealed to the FCC and was told PICON (public need, convenience or necessity) covered our actions, I received a nice letter from the FCC suggesting "Get your ham license."? There wasn't any threat but I knew Morse code, was an EE student, had been messing with electronics for years, so the theory was easy. I received my license 3 weeks later.
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I'm 73 and get your issues about erecting antennas. Fortunately our landlords are healthy 20ish year old girls and are quite willing to help me erect antennas.
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One reason I did the great toss out was my age, there isn't anyway I'd ever use ha;f the stuff, hell I'd bust a gut lifting some of it, life is so much simpler since I got rid of 99% of the dross.?
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
On Monday 27 January 2025 04:43:26 pm wn4isx via groups.io wrote: At one time 88mH (and other value) inductors were as common as roaches and just about as valuable. Today they are scarce, a quick net search didn't find any 'real' 88mH loading coils for sale. I remember seeing them mentioned a fair amount back when, not so much lately. RTTY is a dying data format clinging to life with an amazing tenacity by true fanatics. Almost all are older men, I'd say 70 and up. I can believe that. There are many better, as in faster, more reliable, radio data formats.
If I were starting today I wouldn't bother with RTTY. Since I have a decoder that works extremely well and it might be useful in an emergency.
Plus it took me a year to design, debug and build and is the size of 2 paper back books.
Modern systems are PC/Sound card with an interface to activate the push to talk.
This is a good one stop shop for data modes with fairly objective reviews.
An interesting site. Though he needs to proofread it a bit, and maybe update some stuff. I see where he mentions MFJ, who I hear has pretty much pulled the plug at this point. I also have no use for ARRL lately. I use the free version of Macrium Reflect and have a disk image that converts my general purpose laptop into a dedicated emergency communication PC with all the data software I'm likely to need. I have a number of laptops here that I'm not doing much with, and it should be fairly trivial to dedicate one to that kind of use. Typically I'll make an image of this PC as it is 'now' when a tornado watch is declared, load the radio emergency image and start playing ham radio operator. I haven't been active at all in ages. Been moved over here about 4-1/2 years and I have yet to get any antennas up. At 73 and with ostoporosis I won't be climbing any ladders, and haven't found anybody willing to help out with that even with an offer of compensation. So I have several antennas sitting downstairs, along with some mounts and such, waiting for me to deal with 'em. I did get to meet up with one guy who's down the road a bit, we had a good chat, and he offered me a 2M rig, but I haven't heard back from him since then. I did try out a rollup antenna that's dual-band, and was pleasantly surprised to find out that I could accsss one repeater in particular and check in on a net, which was a bit of a surprise since I'm under a metal roof. I auto-record all the traffic on our primary 2 meter repeater for Skywarn network, I have SDR software for the RSPplay SDR to tune to the other ham repeaters in the area and the US standard Simplex frequency. There's one repeater in the Harrisburg area that carries a skywarn net, and I did get certified for that a while back, but I can't pull that one in directly and that particular repeater doesn't have echolink available. SDR is of some interest to me. But again, that'll depend on antennas... I go from net nut to fully prepared ham in less then 5 minutes.
Of course I'm not totally dependent upon the PC. If it dies I still have voice coms, a solid state office MP3 micro recorder and pen and paper.
The local ham community joins the 4 wheel drive community in the event of a 'bad snow event' like the winter of 1978 when we had 4 feet of snow, drifts 30 feet high and almost nothing could move. The hams and 4 wheelers shuttled nurses and doctors from/to home to work, took food to people who couldn't get out. Stockpiling food is a good thing. I've looked at emcomm stuff, but way too much of it is way too formal and too focused on supporting various officals, not my thing. Ham radio has one advantage over cell service. In the event of a wide area power failure, cell sites will go down when their emergency power dies, hams can operate from a variety of power sources. My setup here included a group 24 AGM that I picked up at a hamfest, but it seems to have reached the end of its life now, won't take or hold a charge, and I am not looking forward to getting that thing back down the stairs to get it to recycling. Or to the cost of replacing it. They provided the communication backbone in New Orleans after Katrina.
I seldom fire up a ham radio except during bad events. My life is too busy with other projects and most ham comms bore me to tears.
YMMV I can understand that. I have run across two clubs, one of them more local but there's not much going on there. The other one much more active, but it's a 100 mile round trip to get to a meeting, and I don't participate much in their stuff any more, aside from reading the mailing list... -- 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
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
At one time 88mH (and other value) inductors were as common as roaches and just about as valuable. Today they are scarce, a quick net search didn't find any 'real' 88mH loading coils for sale.
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RTTY is a dying data format clinging to life with an amazing tenacity by true fanatics. Almost all are older men, I'd say 70 and up.
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There are many better, as in faster, more reliable, radio data formats.
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If I were starting today I wouldn't bother with RTTY. Since I have a decoder that works extremely well and it might be useful in an emergency.
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Plus it took me a year to design, debug and build and is the size of 2 paper back books.
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Modern systems are PC/Sound card with an interface to activate the push to talk.
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This is a good one stop shop for data modes with fairly objective reviews.
http://wb8nut.com/digital/
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I use the free version of Macrium Reflect and have a disk image that converts my general purpose laptop into a dedicated emergency communication PC with all the data software I'm likely to need.
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Typically I'll make an image of this PC as it is 'now' when a tornado watch is declared, load the radio emergency image and start playing ham radio operator.
I auto-record all the traffic on our primary 2 meter repeater for Skywarn network, I have SDR software for the RSPplay SDR to tune to the other ham repeaters in the area and the US standard Simplex frequency.
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I go from net nut to fully prepared ham in less then 5 minutes.
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Of course I'm not totally dependent upon the PC. If it dies I still have voice coms, a solid state office MP3 micro recorder and pen and paper.
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The local ham community joins the 4 wheel drive community in the event of a 'bad snow event' like the winter of 1978 when we had 4 feet of snow, drifts 30 feet high and almost nothing could move. The hams and 4 wheelers shuttled nurses and doctors from/to home to work, took food to people who couldn't get out.
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Ham radio has one advantage over cell service. In the event of a wide area power failure, cell sites will go down when their emergency power dies, hams can operate from a variety of power sources. They provided the communication backbone in New Orleans after Katrina.
https://www.nbcnews.com/id/wbna9228945
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https://mst.rice.edu/PHYS501/SPR2007Papers/Nkung_kat.pdf
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I seldom fire up a ham radio except during bad events. My life is too busy with other projects and most ham comms bore me to tears.
YMMV
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
On Sunday 26 January 2025 02:29:36 pm wn4isx via groups.io wrote: I still have my ancient, circa 1978, TU (terminal unit) that used 88mH telephone loading coils. I've heard of those things for a really long time. Seen them referenced in magazines, etc. But I don't think that I've ever actually run across them... I do have some toroid coils, no idea what they're supposed to be. I should probably hook 'em up to my L/C meter and see what it says. -- 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
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All sorts of stuff:
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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"
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Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
I have several software programs that emulate the old CRT mark/space vertical/horizontal? display with a simulation on the PC screen. It isn't as accurate as the CRT display, I'd say it's about 60% as good, plenty good enough for casual operators like me, but woefully inadequate for a series RTTY operator who operates right at, or below, the ambient noise floor.
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I still have my ancient, circa 1978, TU (terminal unit) that used 88mH telephone loading coils. I test it ever field day.
Field day for non hams is a day when hams all over the US play "it is the end of the world" and try to rack up as many verified 2 way contacts as possible with multipliers for emergency power, solar and other green power (I'm not aware of anyone who uses a wind mill or hydro power but I'm sure there are).
I can operate QRP (low power) from solar on HF and VHF (2M 144MHz).
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Low power RTTY is real challenge and one needs every trick in the book. I have a program written by a friend who used to write signal analysis software for the government. The software takes multiple readings within a single RTTY data bit to insure it's accurate. [And no I can't give it out, she's still tweaking it for commercial applications.]
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She wrote her own GPS decode program, didn't like the delay of commercial ones....
I have some very smart friends.
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Re: I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
On Saturday 25 January 2025 02:48:21 pm wn4isx via groups.io wrote: 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.
Heh. I remember seeing a setup like that. This was so long ago that I can't even remember when it was. Somebody I knew thought that I might perhaps be interested in ham radio, and introduced me to this guy. So I went over to his house and saw his setup, which wss really quite impressive. One of the items there was a mechanical teletype machine, and another one was a scope showing the comparative ampiitudes of the two tones, so he could tune it in. We didn't hit it off for some reason, but I can still remember that bit of equipment... -- 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
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I found a stash of 5 'new old stock' 5CP1 5 inch oscilloscope CRT
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?
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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.
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He bought an Owon AS-201 "retro" scope.
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This is a accurate review, roses and warts.
https://chinese-electronics-products-tested.blogspot.com/p/as201-benchtop-oscilloscope-tested.html
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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.
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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.
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So I called him and explained "I have 5 WWII surplus CRTs... wanna trade?"
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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.
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It really is a nice, basic, emphasis on basic, 'scope.
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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.
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Since my Owon AS-201 is basically "found on the side of the road" I got a heck of a deal.
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He who dies with the most test equipment.... wasted a lot of money.
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Re: What is sidereal time? Why is it used? And How to make it?
The published charts/formula for delay are all wrong, or 'wrong' for certain manufacturers CMOS 555's..
I spent several hours cut and pasting RC values to get the time delay I needed.
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All 555 are not the same.
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Re: What is sidereal time? Why is it used? And How to make it?
On Friday 24 January 2025 06:38:45 pm wn4isx via groups.io wrote: Note 2: The CMOS 7555 are a Xitch to get working properly!
How so? -- 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
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Re: ?My Temperature Probe melted
Try a 15k or 20k pot....turn the knob and the display should change.
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What is sidereal time? Why is it used? And How to make it?
86164.0905??(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??per year than there are sidereal days, similar to an observation of the?.?This makes a sidereal day approximately?365.24/366.24??times the length of the 24-hour solar day.
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https://adsabs.harvard.edu/full/1984IAPPP..17...55D
Pages 55 ~ 61
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I received an email asking "What is sidereal time and where is it used?"
And
"How do you derive it from 60Hz?"
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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
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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.
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Anyway My Crazy Cousin wanted a dual display clock, one display would show Mountain Standard Time, the other Sidereal time, both synched to WWV.
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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.
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I used an inexpensive precision 10MHz canned TTL oscillator with internal heater. She upgraded to a ~$150 GPS disciplined oscillator with a 10MHz output.
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I used a PIC programmed with magic code to convert 10MHz to 60MHz.
http://leapsecond.com/pic/
http://leapsecond.com/pic/picdiv-list.htm
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scroll down to
pd60.asm:;?? PD60 -- PIC "4-pin" frequency divider (10 MHz to 60 Hz)
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You feed 10MHz into the PIC and get 60Hz out, the accuracy of the 60Hz depends on the accuracy of the input 10MHz.
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Then open
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https://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1984IAPPP..17...55D&defaultprint=YES&filetype=.pdf
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And you see one way way to modify 60Hz to feed "sidereal 60Hz" to a LSI clock chip to display sidereal time.
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I used the same logic but with CMOS chips.
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Now if the Leapsecond.com only had a 10MHz to "60Hz Sidereal".....
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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.
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[She also happens to be my favorite cousin. A really nice if somewhat dingbatty person.]
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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.
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I came up with a logic circuit using 74LS chips that achieved the same function. I replaced my 74LS design with the new CMOS.
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Unless you are an astronomer, or total geek, you will never need sidereal time, but this is one 'easy' way to obtain it.
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Of course she could simply have spent ~$200 at
https://brgprecision.com/products/stand_alone_clocks/sidereal.php
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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.
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Note 2: The CMOS 7555 are a Xitch to get working properly!
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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.
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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
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Note: 5: It should be possible to use the leapsecond.com 10MHz to sidereal 1 pps to drive one of those cheap analog clocks.
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They have a 32?kHz crystal, "IC" to produce 1 PPS, it'd require some experimentation but it should work.
Since My Crazy Cousin is dyslexic, like me, analog clocks are viewed as the work of the devil and you are on your own here.
This might help
https://sound-au.com/clocks/timebase.html
and
http://leapsecond.com/pic/picdiv-list.htm
scroll down to
pd29.asm:;?? PD29 -- PIC 10 MHz to best sidereal 1PPS, with sync and milli-step
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Note 5: You can also replace the large coil on regular AC mains powered analog clock with a smaller winding and lower voltage.
https://sound-au.com/clocks/motors.html
https://sound-au.com/clocks/ocm.html
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Mr. Elliot also has a nice circuit for changing 50>60Hz or 60>50Hz to allow clocks from "over there" to work "here."
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My sister has a hideous French clock she loves, it runs on 50Hz and the ESP circuit and replacing the high voltage coil with a low voltage one made her a happy camper.?
I could have divided 60Hz down to 20Hz, used a PLL with divide by 5 to generate 100Hz, divide by 2, but that was too simple. I wanted to play with the ESP circuit.
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I'm ignoring Raspberry and Ardino because I have zero familiarity with programming or interfacing them (and no desire to learn, I ignored Apple and Wang at work and they went away....). Although I am running a Raspberry with a dirt cheap SDR from SDRplay and it is nice. A friend's daughter say the Raspberry up for me.
[ The windows version requires windows 10, ain't gonna happen, I'll learn Linux first.]
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I have enough real electronic projects to keep me busy as long as I'm on this side of the grass.
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Yea I have too much time on my hand this winter.
The only good thing about winter is it does end. [I hope]
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Re: ?My Temperature Probe melted
Simple logic would suggest 10k +/- 2K
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