Maker Pro

Bench power supply upgrade

My ancient Heathkit bench supply died a while ago so I bought one of the 30V 3A variable power supply kits like the link below that are all over eBay to replace/upgrade the insides of it with.

hevans1944

Hop - AC8NS
Jun 21, 2012
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So now I have 30 of them.
Too bad, since you purchased from China, that you have no idea what those 30 "devices" really are. Finding out "fer sure" would cost more... much more... than what you would have spent purchasing from a North American distributor the original lot of 10. But, hey, ya pays yer money and ya makes your choices. I have bought electronics stuff from China, mostly through Amazon. Once I tried to purchase via email exchange for a project that used stepper motors. I have had no problems with Amazon, but there was a huge language problem trying to communicate, both verbally and through documents, with the Chinese. I finally gave up trying to source a motor from China when the person I was trying to buy these motor for decided to purchase them himself.

Still waiting for those motors so I can continue with that, now almost ten-year old, project. Both he and I are getting older, so it may never get finished, but if it does, I will send a link to where you can purchase one... of the stepper motors that is. Cannot say how the motors will be used, because of an NDA I signed for the person who wants the motors.

I need to take some time now to go back and read the whole thread of dialog between you and AudioGuru. If I recall correctly, he was the person who first discovered, and then reported to this forum all those problems in the Asian power supply... not only discovered but also explained and corrected! If it wasn't this thread (which is old) it might be a very much older thread. Whatever... what I need to know now is the final corrected schematic with parts identified by symbol and value. I guess a BOM (Bill of Materials) would be a little much to ask?
when I get a chance I'll refresh my memory about this and test some of them to see if they have the appropriate resistance between the offset pins.
You might as well test them for functionality, too. Some, all, or none of them may be parts actually manufactured by Texas Instruments.
A small ZIF or Zero Insertion Force socket would speed up the testing process. Functionality testing can get complicated really fast. Testing just the two "offset" pins for resistance and rejecting those devices that show "no continuity" is just a minimum test to sort bad from possibly good. Even a "bad" chip could turn out to be "good" if only you knew more about it. And all the "possibly good" devices that "pass" the continuity test could be fakes or defective. However, I think you can now purchase a "smart socket" instrument that analyzes whatever device you insert into it and then tells you the nearest equivalent part number. IIRC, it was a bit pricey... maybe needed a cloud-based database to store specs for every integrated circuit or device it recognized.

Maybe I should use this website's "search function" instead of cluttering us space on your screen!
 

Sidecar Bob

Dec 19, 2021
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Too bad, since you purchased from China, that you have no idea what those 30 "devices" really are. Finding out "fer sure" would cost more... much more... than what you would have spent purchasing from a North American distributor the original lot of 10. But, hey, ya pays yer money and ya makes your choices.
You completely miss the point of what I'm doing here. There is pleasure to be found in doing something without spending any more money than necessary and buying from a North American seller would have meant paying more for shipping than the parts are worth.
I need to take some time now to go back and read the whole thread of dialog between you and AudioGuru. If I recall correctly, he was the person who first discovered, and then reported to this forum all those problems in the Asian power supply... not only discovered but also explained and corrected! If it wasn't this thread (which is old) it might be a very much older thread. Whatever... what I need to know now is the final corrected schematic with parts identified by symbol and value. I guess a BOM (Bill of Materials) would be a little much to ask?
I have been updating the schematic every time I make changes and if/when the project is complete I will post a final version with a list of all of the changes.

This thread was only started 8 months ago. Considering that it is a discussion about an ongoing project (that is on hold while the weather is nice enough to work in the garden and the garage workshop - electronics is primarily a winter activity for me), and that I posted an update just last week I wouldn't say this is an "old thread".
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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You completely miss the point of what I'm doing here. There is pleasure to be found in doing something without spending any more money than necessary and buying from a North American seller would have meant paying more for shipping than the parts are worth.
No, I don't think I missed the point. As I said, ya pays yer money and ya makes yer choices. I prefer not to waste my valuable time trying to use components of unknown origin or quality. It makes troubleshooting much more difficult if you cannot trust that ALL the parts function the way they were originally intended. That is just one of the reasons that I have instruments to measure resistance, capacitance, and inductance of passive components. And instruments to measure wave forms (oscilloscopes) and steady voltages and currents (digital and analog multi-meters).

For my amateur radio hobby, I would own an RF spectrum analyzer and a 2-port vector network analyzer (VNA) if I could afford them. My amateur radio rig has to date cost me upwards of 3000 USD with no end in sight for antennas, feed lines, lightning arresters, etc. It's an expensive hobby, even if you build from scratch. I did that when I got my Novice license in 1962: built the transmitter and its power supply from parts, but built the amateur radio receiver as a Heathkit SB-300. Current rig is an Elecraft KX3 with a 100 watt linear amplifier accessory. Can't use the amp because I have not put up a permanent working antenna here in Florida, the Lightning Capital of the United States. I do have a multi-band vertical that was given to me my a member of the Tamiami Amateur Radio Club here in Venice, but it needs some repairs and a mechanism to lower it to the ground when not in use, especially during thunderstorms.

In the 1970s, I was paying more for the socket than I paid for the integrated circuit that plugged into it. Pay more for shipping than the parts are worth? Ha. That cost is already "built in" to the selling price. My only point was that China is not, and may never have been, a reliable source of electronic components. They seem to be on the same path that plagued Japan after WWII: build cheap copies, but without quality control, and with no respect for intelluctual property rights. In Japan, that eventually changed, but I see no indication, or incentive, for such change in China's business practices.

As an amateur radio operator, or "ham," originally licensed in 1962, but an avid electronics enthusiast and experimenter since the early 1950s when I was living (temporarily) with my paternal grandparents while Mother recovered from tuberculosis of her lungs, I learned very early on how to "make do" with what I had on hand, or could reasonably scrounge from "stuff" thrown away in the alley behind radio and TV repair shops. Alas, consumer electronics is no longer considered "repairable" for profit, so we throw away the baby (television) with the bath water into a landfill. Not a nice place to scrounge for parts IMHO, but there are cheap (when they work) electronics available from Asia via Amazon and eBay. I don't always "buy American" to support my electronics hobby.

This thread was only started 8 months ago. Considering that it is a discussion about an ongoing project (that is on hold while the weather is nice h to work in the garden and the garage workshop - electronics is primarily a winter activity for me), and that I posted an update just last week I wouldn't say this is an "old thread".
I suppose "old" is relative. The thread I remember was much, much older than eight months ago. Here is a link to discussions involving @Audioguru that date back to 2017, almost ten years ago. We re-invent the wheel quite often here, mainly to accommodate new members who cannot be bothered to research anything. The most popular topics seem to revolve around LEDs and/or how to re-charge various batteries. Congratulations to you for trying something a little more sophisticated and perhaps challenging.

Apparently, like you, I am a "hands on" experimenter and hate to spend too much money for parts that I know can be obtained much cheaper overseas than in the North American continent, excluding Mexico whose government behaves like a third-world banana republic. Mexico could be our "China" here, close to home with a hard-working but lower paid population. However, for reasons of money, power, and/or corruption it isn't. So I mostly buy cheap, passive, Chinese parts from Amazon and hope for the best. At least with Amazon Prime I know something will be delivered and about when that will occur. And Amazon has a really nice return and refund or replace policy for most items. If I need some circuit boards made, I will probably try to purchase those from China too. Most PCB shops in the US have been legislated out of existence by unaffordable pollution-control polices, but I still know how to make my own single-sided copper boards. Just have to be careful when and where I dispose of the chemicals, so as not to contaminate my well water.:cool:
 

Sidecar Bob

Dec 19, 2021
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Spending lots of money on your main hobby is one thing but for me electronics is primarily a means to an end (something I do to make things for my motorcycles and model trains and household projects) so it is far down the list of things I spend money on.
And in this case, a big part of the project is to re-learn a lot of the stuff I've forgotten since i was actively involved in electronics and learn about things that weren't invented in the 1980s. The issues I've had to deal with in this project have taught me a lot so even if I end up scrapping the Chinese board entirely it will have been worthwhile (although having seen videos of them working I can't see any reason that will be necessary).

Re cost of shipping vs value of items, the Canadian sources I checked wanted from [imath]8 to[/imath]20 for shipping, which is ridiculous compared to 3 lots from different sellers for a total of about $8 including shipping.

Re reliability of Chinese electronics, a lot of the consumer electronics we buy (including most brand name products) are made there so we know they can produce good, reliable parts (whether my Aliexpress bargains are close to that level is to be seen).
US vs Chinese quality? Let me tell you a story: A certain major US based manufacturer of model trains was known for producing locomotives that were noisy & jerky out of the box but could become really good runners if you replaced the factory applied grease with toothpaste and ran it in each direction for several hours to lap everything in before flushing out the toothpaste and re-lubricating.
When they moved production to China they made all of the parts to the same drawings and with the same materials but those locomotives run smoothly & quietly right out of the box.

Re old threads, I moderate on a couple of motorcycle forums and it isn't uncommon for newbies to revive threads 10-15 years old to ask someone who hasn't been on the forum for nearly that long about some detail of what they posted. That is old.
BTW: 2017 was only 5 years ago.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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BTW: 2017 was only 5 years ago.
Ooops! I really HATE getting older and forgetting how to do simple math. March 2017 was three months after we moved into our house in South Venice, FL. That's when my pacemaker/defibrillator started shocking me a
 

Sidecar Bob

Dec 19, 2021
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I'm the opposite. I keep thinking that 2017 was just a couple of years ago.
 

hevans1944

Hop - AC8NS
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BTW: 2017 was only 5 years ago.
Hmmm. I HATE getting old and forgetting how to do simple arithmetic. Five years seems like eternity here in Paradise.

And I do sometimes read old threads, posted below threads like this one under the banner Similar threads. Don't often respond with a comment though, unless I forget to look at the posting dates. You are correct, there is a lot of good information in those older posts if you take the time to carefully read them and separate the "wheat" from the "chaff" and ignore the wild-ass speculation. Unfortunately my motorcycle riding days are over, but wife has shipped here, and had professionally restored, my Honda Shadow ACE 1100cc cruiser for my "last ride" ceremony with my ashes. Wife and I traveled far and wide on that bike the first few years we were married, but she says I can't ride anymore unless I convert to a trike. Too dangerous because of my heart conditions, other comorbidity, and age. But I can't afford a trike, or even an F-150E electric pickup truck.

At one time my brother and I "owned" an O-gauge, three-rail, AC motor-driven electric train set. Dad was a navigator/bombardier on B-47s working for the Strategic Air Command (SAC). The Government moved us around a lot, but the train set was always carefully disassembled and boxed before we moved. The last time I remember setting it up was in the attic of a rental house in Phoenixville, PA while Dad was at nearby Valley Forge Army Hospital recovering from tuberculosis of the kidneys.

The train set eventually wound up in Dayton, Ohio, after Dad retired. He had purchased a lot of rolling stock and accessories like electrified turnouts, signal lights, and a flat-car lumber un-loader, just to name a few. Once in a while he would show up for Christmas with a new locamotive, always a steam locamotive, never a diesel-electric. In Dayton, Dad was in the process of getting a divorce from our mom. I had joined the Air Force about that time and I was surprised to find out he had sold or given away to his American Legion "buddies" the entire train collection. I hope he found it to be a good return on his investment.

Please let us know how your Heathkit power supply restoration/upgrade turns out. I am thinking of attempting the same sort of thing using an AT switch-mode power supply as a bench power supply... plenty of "stuff" on the Internet on how (maybe) to do that.
 

Sidecar Bob

Dec 19, 2021
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I model in HO scale. Most of mine run on variable DC but a few run on a form of AC... If you want to see some interesting electronics look up Digital Command Control.

The bike in the rear ('83 GL1100 with Dnepr sidecar) is what I drive in the summer and the one in front (originally an '83 CX650E with Velorex sidecar body on Ural frame) is what I drove it to work every day in the cold half of the year (it sees a lot less use since I retired).
I plan to continue as long as I am able to climb on ;-)
2 outfits May 2022 1.jpg

I may eventually build a fixed voltage supply from a computer PSU too if I think it will be useful. One of these (available for about $5) might be a good place to start
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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When my two boys and two girls were of the "right" ages to appreciate it, I began putting together a small HO layout. This would have been in the 1970s IIRC. Not a single one of them showed any interest in model railroading, much to my dismay, as I had an entire basement in which to build it... less room dedicated to laundry and storage and a Shopsmith woodworking shop and a cartridge re-loading bench.

I went ahead anyway and purchased a four-by-eight foot sheet of plywood and some two-by-four lumber to make a table to erect track on. Also read lots of model railroad magazines with their impressively realistic photos of layouts that other people, smarter, wealthier, and/or more committed than I, had published. I even was offered the opportunity to visit an organ recital that was conducted in a two-story brick building separate from the living quarters of the owner. Seems he was into restoring old church and theater pipe organs. And his side hobby was building model train layouts.

This visit was "by invitation only," but I had an acquaintance who was also interested in salvaging and restoring pipe organs, mostly from churches, and he invited me to accompany him. One of the things that I learned is the "pipes" you see behind the pulpit in a church organ are fake. The real sound takes place out of sight and the real sound-producing "instruments" look like junk, or at the very least cobbled together from random pieces. Fascinating, but disappointing to find out what was really "behind the curtain". It was about this time that electronics for consumers was really beginning to take off in a big way. IIRC, this applied in spades to model railroading. So, pulse-width-modulated, multiple engines each with remote speed and direction control from anywhere along the line became instantly possible and practical, albeit a bit pricey.

Today I looked at the 2022 Lionel online catalog. My, how things have changed! Of course, Lionel has retained their three-rail AC powered system but now have added HO gauge and LOTS of "bells and whistles" including Bluetooth and Voice remote control while still retaining the legacy system "controls" which offered forward, reverse, and stop with a limited range of speed control. I remember the legacy set my brother and I had set up in Phoenxiville, PA, experienced problems because the connecting pins that held the tracks together had became loose from all the moving the Air Force put our family through over a period of twenty years. Still, we had a lot of fun with it. Years later, after I had children of my own, I pined for an HO layout, but it took several years before I could afford to buy just a beginners set. Eventually my kids grew up and moved away and the train set disappeared. <sigh>

Ahh, Digital Command Control is described here. This may have been what I was reading about in the 1970s. And Lionel may not be selling their legacy three-rail AC system in HO gauge. It's a huge catalog and I haven't examined it in detail yet.

I admire the sidecars on your motorcycles. Maybe wife would let me ride again if I put one on my Honda... Nah, I would probably have to sit in the sidecar while she drove the bike, so that would be a non-starter for me. Of course I wouldn't need any rain gear like the driver would... it rains a LOT here in southwestern Florida because of moisture-laden air blowing in from the Gulf of Mexico. Up North, when we were riding together in tandem, we both had rain gear and visor helmets, but I would usually pull off the road and park under an overpass or under a bridge when a heavy rain caught up with us. Automobile drivers have a hard time seeing motorcycles even in broad daylight. Add in some rain and it gets to be real problem, so we get off the road.

The "breakout" terminals (from China!) for the ATX form-factor power supply looks interesting.

73 de AC8NS (Hop)
 
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Sidecar Bob

Dec 19, 2021
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I got my first motorcycle because I was getting tired of taking the bus to work. A friend at work attached a sidecar to his bike for winter; I couldn't afford a bike and a car and I preferred to have a bike so I decided to do the same. That was OK but I spent a lot of summer weekends fixing the damage winter did (it takes longer when you have to get it back together in time to drive to work Monday morning, then take things apart again next weekend) so when we could afford it I bought a 2nd bike and changed the license plate and insurance over in the spring & fall.

Several decades later they closed the paved road I used to get to work to replace a couple of bridges so I started taking one of the dirt/gravel roads that I normally didn't take on 2 wheels and realized how much better the scenery there was than going through town so I convinced my wife that I should get a 2nd sidecar and the outfit in my avatar pic was born.
The only thing I don't like about having a sidecar is that I never get to ride in it myself ;)

If you think Lionel has come a long way since the '70s have a look at some of the stuff Rapido Trains is making. In addition to DCC with sound and underbody detail like this the interiors of the passenger cars have the correct colours for everything, right down to the tablecloths and plates in the dining cars.
http://www.wig-wag-trains.com/Rapido/Pictures/Undebody.JPG
 
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