Date   

Re: Chaining power supplies together.

Dave Peterson
 

Here's a specific example of what I'm thinking of doing with such a scenario:

I'd like to be able to run 465 boards on the bench to test them before reassembling on the chassis. I have a variety of power supplies available to me: TM503 with a PS503A (+/- 20v), a Systron-Donner TL8-3 bench supply that can drive 32v, and more.

Can I chain these together to make, for example, +55v without doing harm?

Dave

On Saturday, May 1, 2021, 02:52:35 PM PDT, Harvey White <madyn@dragonworks.info> wrote:

Definitely.  Most power supplies take a very dim (as in permanently off)
view of reverse voltage applied to their terminals.  Most also don't
like to be tied to another power supply in parallel unless designed for it.

If you're going to charge a battery with a Chinese (or many other types)
power supply, put a series diode in so that the supply can't be fed by
the battery.

Harvey


On 5/1/2021 5:38 PM, Ed Breya via groups.io wrote:
Be sure to add an external reverse protection diode across each output, in case there isn't one built in.

Ed






Re: Chaining power supplies together.

Harvey White
 

Definitely.  Most power supplies take a very dim (as in permanently off) view of reverse voltage applied to their terminals.  Most also don't like to be tied to another power supply in parallel unless designed for it.

If you're going to charge a battery with a Chinese (or many other types) power supply, put a series diode in so that the supply can't be fed by the battery.

Harvey

On 5/1/2021 5:38 PM, Ed Breya via groups.io wrote:
Be sure to add an external reverse protection diode across each output, in case there isn't one built in.

Ed





Re: Chaining power supplies together.

Dave Peterson
 

Could you elaborate Ed? Seems such diodes might need to be robust. Any particular type that's appropriate? I take it these need to have a reverse breakdown voltage above the supply? But are there particular ones for these voltage levels? Would this be at each supply - from out to common of each?

Seems one thing to understand a reverse diode as protection in theory, another in practice.

Thanks for the input.
Dave

On Saturday, May 1, 2021, 02:38:59 PM PDT, Ed Breya via groups.io <edbreya=yahoo.com@groups.io> wrote:

Be sure to add an external reverse protection diode across each output, in case there isn't one built in.

Ed


Re: Chaining power supplies together.

Ed Breya
 

Be sure to add an external reverse protection diode across each output, in case there isn't one built in.

Ed


Chaining power supplies together.

Dave Peterson
 

I just want to check myself. I don't want to overlook something and break my toys:

Is it safe, and a typical thing to do, to daisy chain power supplies to get a higher voltage than any one supply can provide?

I'm talking about TM500/5000 plug-in power supplies with one or two outputs with an ungrounded common. Say I have two 20v supplies: can I tie the common of the 2nd to the output of the 1st and get 40v between the common of the 1st and the output of the 2nd? Safely?

Seems appropriate, but haven't seen it done or talked about before. I don't want to blow anything up if I'm forgetting something fundamental here.

Thanks,
Dave


Re: My wife makes it possible for me to do this

 

Hi Phil,
I definitely learned a lesson when she was recuperating. Now I do most of the things you do and I also walk the dogs 4 or 5 times each day starting at 4AM! in the morning. If I'm lucky they wait until 5AM to start making noise. Because I'm walking the dogs now she can sleep until 6:00 to 6:30AM when she normally wakes up.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Phillip Potter
Sent: Saturday, May 01, 2021 12:40 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] My wife makes it possible for me to do this

Hi Dennis,
Glad to hear that she is on the mend.
After 42 years of marriage, I can say this...
My wife and I have taken to "thanking" each other for the things that the other does for us; like cooking, etc.
I have taken on cleaning up if she cooks and visa versa.
I am the sys op, driver, and geek. I take care of my own laundry, make the bed almost every day, and clean up after myself, while she takes care of the dog run (you know...).
It's a shared life where I look for ways to pitch in without being asked and we are still happily married.
Phil

On 4/3/2021 7:15 PM, Dennis Tillman W7pF wrote:
A little more than 3 weeks ago I had no idea my life was about to be
turned on its head.
Marian's hip replacement operation went extremely well as far as the
medical staff was concerned.
She was offered numerous pain medications in advance which was reassuring.
Unfortunately one by one we discovered she had adverse reactions to
each of them. There many sleepless nights spend in endless pain
followed by irrational emotional ups and downs during the days. I
spent the next 3 weeks doing everything she used to do around the
house in addition to taking care of her every need 24 / 7. Each day
ended with my being exhausted and falling into bed for a few hours before repeating the same thing again.

My aha moment came when, after 5 days of total exhaustion (me, not
her), she screamed at me "Now do you see how much I do around here so
you can sit in your room on the computer all day long?"
"It would be nice if you said thank you once in a while when I got
home from work!"

I thought better of opening my mouth at that moment to tell her all
the things I was doing:
All the cooking for both of us including food shopping; vacuuming,
laundry, dishes; feeding the dogs (they eat almost 50lbs of raw dog
food each month) twice a day, walking them 6 times per day; helping
her in and out of bed, sitting, standing, walking:, taking her almost
daily to and from appointments with physical and occupational
therapists, pain management specialists, doctors, etc; helping her
with her rehabilitation and her exercises; buying medical necessities
like canes, walkers, stools, shower seats (since she can't stand
long), back pillows, ice packs, prescriptions, etc; going into work
remotely, and eventually in person, since so many people depend on her.

The truth is undeniable: Marian makes it possible for me to be the
moderator of TekScopes, something I love to do.

3 days ago (and exactly 3 weeks after her surgery) she turned the corner.
She was sleeping through the night without pain, walking with only a
cane, eating the usual things, and going to work. For the next 6 weeks
I will still have to drive her everywhere. By now I have no problem
feeding and walking our five Golden Retrievers. They are still more
than a little upset they haven't been able to snuggle with her in bed.
Long ago we bought a California king bed so 300+ pounds of dogs could
all fit in the bed at the same time. She hinted today that she may let
one of them sleep in bed with her tomorrow night. Knowing her, a day
later she will feel sorry for the other four and let all five join her.

Dennis Tillman W7pF











--
Dennis Tillman W7pF
TekScopes Moderator


Re: My wife makes it possible for me to do this

Phillip Potter
 

Hi Dennis,
Glad to hear that she is on the mend.
After 42 years of marriage, I can say this...
My wife and I have taken to "thanking" each other for the things that the other does for us; like cooking, etc.
I have taken on cleaning up if she cooks and visa versa.
I am the sys op, driver, and geek. I take care of my own laundry, make the bed almost every day, and clean up after myself, while she takes care of the dog run (you know...).
It's a shared life where I look for ways to pitch in without being asked and we are still happily married.
Phil

On 4/3/2021 7:15 PM, Dennis Tillman W7pF wrote:
A little more than 3 weeks ago I had no idea my life was about to be turned
on its head.
Marian's hip replacement operation went extremely well as far as the medical
staff was concerned.
She was offered numerous pain medications in advance which was reassuring.
Unfortunately one by one we discovered she had adverse reactions to each of
them. There many sleepless nights spend in endless pain followed by
irrational emotional ups and downs during the days. I spent the next 3 weeks
doing everything she used to do around the house in addition to taking care
of her every need 24 / 7. Each day ended with my being exhausted and falling
into bed for a few hours before repeating the same thing again.

My aha moment came when, after 5 days of total exhaustion (me, not her), she
screamed at me
"Now do you see how much I do around here so you can sit in your room on the
computer all day long?"
"It would be nice if you said thank you once in a while when I got home from
work!"

I thought better of opening my mouth at that moment to tell her all the
things I was doing:
All the cooking for both of us including food shopping; vacuuming, laundry,
dishes; feeding the dogs (they eat almost 50lbs of raw dog food each month)
twice a day, walking them 6 times per day; helping her in and out of bed,
sitting, standing, walking:, taking her almost daily to and from
appointments with physical and occupational therapists, pain management
specialists, doctors, etc; helping her with her rehabilitation and her
exercises; buying medical necessities like canes, walkers, stools, shower
seats (since she can't stand long), back pillows, ice packs, prescriptions,
etc; going into work remotely, and eventually in person, since so many
people depend on her.

The truth is undeniable: Marian makes it possible for me to be the moderator
of TekScopes, something I love to do.

3 days ago (and exactly 3 weeks after her surgery) she turned the corner.
She was sleeping through the night without pain, walking with only a cane,
eating the usual things, and going to work. For the next 6 weeks I will
still have to drive her everywhere. By now I have no problem feeding and
walking our five Golden Retrievers. They are still more than a little upset
they haven't been able to snuggle with her in bed. Long ago we bought a
California king bed so 300+ pounds of dogs could all fit in the bed at the
same time. She hinted today that she may let one of them sleep in bed with
her tomorrow night. Knowing her, a day later she will feel sorry for the
other four and let all five join her.

Dennis Tillman W7pF




Save this 533A from the trash in Arlington Virgina #photo-notice

Reddy
 

This was my uncles scope. He passed away last year. I'm going through his stuff before the property gets sold. I thought perhaps someone here on the east coast would want this one, otherwise it get loaded in the dumpsters. Too big a scope for me. The cost is zero, it's free. Needs to go to a good home to be loved.

It comes with a CA and D plugin. The drawer has some probes and other parts too. There are manuals for the 533A, CA and the D.

I suspect the last time it was used was the early 70's as there is a 1969 HeathKit catalog that has some of my uncles notes written on it that was with the manuals.

I opened up the case and saw that one resistor is burnt up, otherwise all looks good to me. All the tubes are in there.

It is located in my workshop at home in Arlington Virginia. PM if interested


Re: 465M

DaveH52
 

You can try to find a HV probe like the ones used back when TV sets had CRTs (like I did). The CRT beam current shouldn't be that high so that it presents much of a load. I now recall that I did have an issue with the insulation failing on the HV flying lead. I painted it with super corona dope and mummified it with tape because replacing it seemed to be out of the question.


Can anyone use a Type Z P6023 probe?

 

This time I'm sure I don't need this probe.
I have a P6023 probe lying around for a long time with nothing that uses it.
It is a low capacitance probe (12pF, 8Meg Ohms, 10X attenuation, 1000V Max).
It has thumb-wheel adjustment for DC Attenuation calibration, and for AC
Compensation. It uses the threaded tips from the mid-1960s. I don't have any
of the accessories.
It was designed for the Z Plugin but it also works on any of the
differential amplifier plugins as well.
If you are interested contact me off list at dennis at ridesoft dot com.
Dennis Tillman W7pF




--
Dennis Tillman W7pF
TekScopes Moderator


Re: Tektronix Probe Replacement Parts and Accessories

Tom Phillips
 

Thanks for compiling the document Dennis. I know that it takes a lot of effort to do such projects.


Re: Tektronix Probe Replacement Parts and Accessories

 

Hi david,
The picture never appears in the link you provided.
However, the complete manual for the P6204 can be downloaded from TekWiki:
https://w140.com/tekwiki/wiki/Main_Page

The manual has a complete breakdown of the probe listing every part that goes into it.
The manual is at https://w140.com/tek_p6204.pdf
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David Sidrane
Sent: Saturday, May 01, 2021 6:13 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Tektronix Probe Replacement Parts and Accessories

Thank you Dennis!

By chance do you have the part number for the TeKProbe BNC with the 2 locking rings?

Shown here without the 2 locking rings. https://images.app.goo.gl/MUVd68ojYxeACkMB7







--
Dennis Tillman W7pF
TekScopes Moderator


Re: OT! OT! --- E-bay fee change -- OT! OT! Cross posted with HP group.

 

Auctions have been around since at least 500 B.C. since they promise to fetch as high a price as possible for the seller while at the same time offering to the buyer the prospect of buying items at bargain prices or perhaps buying items that would be difficult to buy in any other way.

Complaining about the latest changes in eBay's fees, or requirements etc., as many members are doing, is a waste of time. The auctioneer, eBay in this case, is entitled to collect a fee for providing the auction venue and for running it. The shipping companies all charge virtually the same price (monopolistic competition) so there is nothing you can do about that fee.

A far more useful way to spend your time is learning how to get what you want at the lowest price (if you are a buyer) or how to sell it at the highest price (if you are a seller). Almost everything you need to know to be more successful can be found in "Snipers, Shills, & Sharks : eBay and Human Behavior", by Ken Steiglitz, ISBN-13: 978-0-671-12713-2 and ISBN-10: 0-691-12713-1, 381.177015193-dc28.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of -
Sent: Friday, April 30, 2021 10:30 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] OT! OT! --- E-bay fee change -- OT! OT! Cross posted with HP group.

Dennis,

I agree with everything that you said. However I think that what people truely object to are the *never-ending* price increases from E-bay. PLUS all of the other charges (PayPal and Global Shipping for example) for services that they force buyers and sellers to use. Personally, I've been a buyer and a seller on Ebay since the first year that they started I've seen their fees rise from a FLAT 2% to whatever the combined totals are today. I quit sellling on Ebay about 5 years ago after I sold ONE item for $200 and was charged slightly over $22 for Ebay and PayPal only and shipping not included. But as you point out Ebay is a private company and isn't beholden to it's buyer and sellers so they have decide if they want to use it or not. However, as far as I'm concerned, E-bay is still the only serious game in town if you want to sell something for a decent price. And it's also usually the only place where most individuals can buy the specialized test equipment or other items that we desire.

Overall; despite it's constant cost increase, I'm very pleased to have seen the rise of Ebay. I've made a pile of money selling TE and other items that I would never have been able to sell without them and I've also been able buy books, TE and some other items that I would never been able to find, or have been able to afford, from the old regular TE suppliers such as Tucker Electronics.




--
Dennis Tillman W7pF
TekScopes Moderator


Re: Tektronix Probe Replacement Parts and Accessories

Lawrance A. Schneider
 

On Fri, Apr 30, 2021 at 11:06 AM, Dennis Tillman W7pF wrote:


I assembled together a PDF for the Probe Replacement Parts and Accessories
for most of the Tek Probes.
Thank you!! larry


Re: Tektronix Probe Replacement Parts and Accessories

David Sidrane
 

Thank you Dennis!

By chance do you have the part number for the TeKProbe BNC with the 2 locking rings?

Shown here without the 2 locking rings. https://images.app.goo.gl/MUVd68ojYxeACkMB7


Re: TDS 380 Attenuator Resistor Replacement Specs

Richard Peterson
 

Quick update - I installed a pair of 1/4 watt resistors to achieve 49.5 ohm to match channel 2 (https://groups.io/g/TekScopes/photo/263498/3217080?p=Created,,,20,2,0,0). I now have a good signal through the first relay. Still no CH1 display, so I'll have to do some signal tracing through the attenuator board and beyond to see where the signal dies.

A note to anyone working on the TDS3xx series. The ceramic attenuator board is not easy to solder. My first attempts to attach the resistors to the trace betwee the two SMD capacitors in the photo was an epic fail using a T18-BR02 fine point bent tip . . . I ended up using my hot air station which worked better. Hopefully the next issue I find is beyond the attenuator board so work will be easier.


Re: OT! OT! --- E-bay fee change -- OT! OT! Cross posted with HP group.

Tom Gardner
 

A couple of my bookmark searches are
 (datron,fluke,valhalla) (reference,calibrator) -prt -pressure -thermistor -loop -process
 tektronix  1502 -1502b -1502c -1503b -1503c
limited to UK only or EU only or within a distance
most recent first

On 01/05/21 05:16, Martin wrote:
Dave,

On 30. Apr 2021, at 22:56, Dave Seiter <d.seiter@att.net> wrote:
...Creative search parameters can weed out unwanted listings, but not all the time...
Some years ago Ebay "modified" its search algorithms, leading to a ban of wildcards that worked well before. Now the search is doing whatever it likes, its intransparent. VERY VERY OFTEN I get thousands of hits in the automotive sector for items that don't even share a single search term in their title... (searching for a FET from Tektronix, for instance).

The only way I figured out to avoid this is only searching for auctions...

cheers
Martin




Re: OT! OT! --- E-bay fee change -- OT! OT! Cross posted with HP group.

Dave Seiter
 

"-" is what I use all the time, and it seems to produce the oddest results on ebay.  Sometimes I get more hits when limiting the results.

On Friday, April 30, 2021, 10:13:29 PM PDT, - <rrrr6789@gmail.com> wrote:

  That sounds like Google's search results.  I can search for
"doublewhammyjammertityflopper" and get hits for hundreds of sites that say
"we sell doublewhammyjammertityflopper" but of course, they don't.  Neither
Ebay or Google are as useful or as useable as they used to be.

  Liberal use of the - search directive helps considerably.  "FET"
"Tektronix" -ford -chevy -audi -bmw -wv -toyota -nissan

On Sat, May 1, 2021 at 12:16 AM Martin <musaeum@arcor.de> wrote:

Dave,

On 30. Apr 2021, at 22:56, Dave Seiter <d.seiter@att.net> wrote:
...Creative search parameters can weed out unwanted listings, but not
all the time...

Some years ago Ebay "modified" its search algorithms, leading to a ban of
wildcards that worked well before. Now the search is doing whatever it
likes, its intransparent. VERY VERY OFTEN I get thousands of hits in the
automotive sector for items that don't even share a single search term in
their title... (searching for a FET from Tektronix, for instance).

The only way I figured out to avoid this is only searching for auctions...

cheers
Martin






Re: OT! OT! --- E-bay fee change -- OT! OT! Cross posted with HP group.

-
 

That sounds like Google's search results. I can search for
"doublewhammyjammertityflopper" and get hits for hundreds of sites that say
"we sell doublewhammyjammertityflopper" but of course, they don't. Neither
Ebay or Google are as useful or as useable as they used to be.

Liberal use of the - search directive helps considerably. "FET"
"Tektronix" -ford -chevy -audi -bmw -wv -toyota -nissan

On Sat, May 1, 2021 at 12:16 AM Martin <musaeum@arcor.de> wrote:

Dave,

On 30. Apr 2021, at 22:56, Dave Seiter <d.seiter@att.net> wrote:
...Creative search parameters can weed out unwanted listings, but not
all the time...

Some years ago Ebay "modified" its search algorithms, leading to a ban of
wildcards that worked well before. Now the search is doing whatever it
likes, its intransparent. VERY VERY OFTEN I get thousands of hits in the
automotive sector for items that don't even share a single search term in
their title... (searching for a FET from Tektronix, for instance).

The only way I figured out to avoid this is only searching for auctions...

cheers
Martin






Re: OT! OT! --- E-bay fee change -- OT! OT! Cross posted with HP group.

 

Dave,

On 30. Apr 2021, at 22:56, Dave Seiter <d.seiter@att.net> wrote:
...Creative search parameters can weed out unwanted listings, but not all the time...
Some years ago Ebay "modified" its search algorithms, leading to a ban of wildcards that worked well before. Now the search is doing whatever it likes, its intransparent. VERY VERY OFTEN I get thousands of hits in the automotive sector for items that don't even share a single search term in their title... (searching for a FET from Tektronix, for instance).

The only way I figured out to avoid this is only searching for auctions...

cheers
Martin

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