Author Topic: What did you buy today? Post your latest purchase!  (Read 1234194 times)

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Online blueskull

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Re: What did you buy today? Post your latest purchase!
« Reply #4925 on: December 03, 2017, 08:50:06 am »
New big toy I just received: 150 pcs of TO247, 80mR, 1200V JFET. Gotta build a (hopefully) 100kV, optically triggered high speed 50ns Tr/Tf power switch.
 

Offline Mr. Scram

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Re: What did you buy today? Post your latest purchase!
« Reply #4926 on: December 03, 2017, 09:06:15 am »
:-DD

I know it's just a joke, but I'm not sure the tax man will smile upon fraudulent invoices or the promise of them.
 

Offline MasterTech

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Re: What did you buy today? Post your latest purchase!
« Reply #4927 on: December 03, 2017, 10:08:13 am »
New big toy I just received: 150 pcs of TO247, 80mR, 1200V JFET. Gotta build a (hopefully) 100kV, optically triggered high speed 50ns Tr/Tf power switch.
Is that something commercially available or already tried out or are you just testing a new concept?
 

Online blueskull

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Re: What did you buy today? Post your latest purchase!
« Reply #4928 on: December 03, 2017, 10:28:26 am »
New big toy I just received: 150 pcs of TO247, 80mR, 1200V JFET. Gotta build a (hopefully) 100kV, optically triggered high speed 50ns Tr/Tf power switch.
Is that something commercially available or already tried out or are you just testing a new concept?

https://www.mouser.com/ProductDetail/USCi/UJN1208K/?qs=%2fha2pyFadugrmm1qxKNPlWgQ5o8iucv7kjh9giooOYs%3d

Devices are available, power module design is my own.
 

Online Circlotron

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Re: What did you buy today? Post your latest purchase!
« Reply #4929 on: December 03, 2017, 11:59:19 am »
New big toy I just received: 150 pcs of TO247, 80mR, 1200V JFET. Gotta build a (hopefully) 100kV, optically triggered high speed 50ns Tr/Tf power switch.
Is that something commercially available or already tried out or are you just testing a new concept?

https://www.mouser.com/ProductDetail/USCi/UJN1208K/?qs=%2fha2pyFadugrmm1qxKNPlWgQ5o8iucv7kjh9giooOYs%3d

Devices are available, power module design is my own.
Top of the Mouser page says rdson is 80mR. Halfway down it says 230mR.   :-//
Edit - seems to be cold and hot values.
« Last Edit: December 03, 2017, 12:02:02 pm by Circlotron »
 

Offline cdev

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Re: What did you buy today? Post your latest purchase!
« Reply #4930 on: December 03, 2017, 01:16:59 pm »
Please be extremely careful with those high voltages.

We want you to remain a healthy participating member of this community for a long time to come.


New big toy I just received: 150 pcs of TO247, 80mR, 1200V JFET. Gotta build a (hopefully) 100kV, optically triggered high speed 50ns Tr/Tf power switch.
Is that something commercially available or already tried out or are you just testing a new concept?

https://www.mouser.com/ProductDetail/USCi/UJN1208K/?qs=%2fha2pyFadugrmm1qxKNPlWgQ5o8iucv7kjh9giooOYs%3d

Devices are available, power module design is my own.
"What the large print giveth, the small print taketh away."
 

Online blueskull

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Re: What did you buy today? Post your latest purchase!
« Reply #4931 on: December 03, 2017, 01:32:58 pm »
Please be extremely careful with those high voltages.

Indeed. When playing with HV, safety always comes first. From day 1 of all of our HV experiments, safety was always the first subsystem to be designed.
Capacitors are sized to allow desired performance while having as little energy stored as possible, and safety discharging methods are always tripled.
All communication and telemetry are over either certified HV probes or optical fiber, and blast shields are always used as per part of lab regulation.
For some high power/high energy systems, we have Faraday cages or acrylic houses to isolate the test setup from people, and we operate test equipment over fiber Ethernet.
For the last line of defense, we always, no exception, have at least 2 people in the lab when doing experiments above 50V, 20mA, and one being far away from HV, essentially a human WDT.
 

Offline rsjsouza

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Re: What did you buy today? Post your latest purchase!
« Reply #4932 on: December 03, 2017, 02:45:03 pm »
essentially a human WDT.
A WHT perhaps? :D
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline MasterTech

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Re: What did you buy today? Post your latest purchase!
« Reply #4933 on: December 03, 2017, 06:07:27 pm »
New big toy I just received: 150 pcs of TO247, 80mR, 1200V JFET. Gotta build a (hopefully) 100kV, optically triggered high speed 50ns Tr/Tf power switch.
Is that something commercially available or already tried out or are you just testing a new concept?


Devices are available, power module design is my own.
Yes, I meant the concept of switching HV with a string of semiconductors.  Cause I doubt youll be able to equalize all the gate voltages with that HV and steep pulse
 

Online blueskull

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Re: What did you buy today? Post your latest purchase!
« Reply #4934 on: December 03, 2017, 06:21:13 pm »
Yes, I meant the concept of switching HV with a string of semiconductors.  Cause I doubt youll be able to equalize all the gate voltages with that HV and steep pulse

Trade secret. I used a different, scalable, confidential topology than the others, but the ideas are alike. Check out these:

Medium Voltage Power Switch Based on SiC JFETs, by Xueqing Li, et al.
Balancing Circuit for a 5kV/50ns Pulsed Power Switch Based on SiC-JFET Super Cascode, by J. Biela, et al.
Stacked high voltage switch based  on  Sic  VJFETs, by Peter Friedrichs, et al.
 

Offline vk6zgo

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Re: What did you buy today? Post your latest purchase!
« Reply #4935 on: December 04, 2017, 09:48:22 am »
essentially a human WDT.
A WHT perhapps? :D

If you mean someone standing by the main breaker, say so!!

This was standard practice with anything reasonably "hot", but most transmitters, for instance, do have
quite a lot of personnel protection built in.

Thousands of people in Transmitter sites, over decades, worked safely with high voltage equipment by the application of simple safe working rules.
In my own experience, nobody I worked with suffered severe Electric shocks causing injury..
Two people died in aircraft crashes, & two others in falls.

The "Aiieee! The sky is falling!" approach is counterproductive.
Working with high voltages is much less dangerous than the construction industry
 
 

Offline Rémi

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Re: What did you buy today? Post your latest purchase!
« Reply #4936 on: December 04, 2017, 06:28:24 pm »
I bought a Lecroy LC334a for parts or not working on Ebay for 200$. The oscilloscope doesn't turn on, we'll see if I can fix it. This is my Christmas gift to myself, I was looking for a 4 channels scope since a long time. If someone is selling PP06 probes I would be interested. Now I'm waiting for delivery......
 

Offline rsjsouza

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Re: What did you buy today? Post your latest purchase!
« Reply #4937 on: December 04, 2017, 11:23:14 pm »
essentially a human WDT.
A WHT perhapps? :D

If you mean someone standing by the main breaker, say so!!
Certainly. A WatchHuman TimerR is quite effective in preventing accidents and keeping each other in check. You are absolutely correct in saying that, with proper procedure, equipment and techinques, high voltage is very safe.

Do they still use padlocks on breakers and doors?
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline Mr. Scram

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Re: What did you buy today? Post your latest purchase!
« Reply #4938 on: December 04, 2017, 11:30:46 pm »
I bought a Lecroy LC334a for parts or not working on Ebay for 200$. The oscilloscope doesn't turn on, we'll see if I can fix it. This is my Christmas gift to myself, I was looking for a 4 channels scope since a long time. If someone is selling PP06 probes I would be interested. Now I'm waiting for delivery......
I like how much it looks like a microwave in the thumbnail.
 

Offline onesixright

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Re: What did you buy today? Post your latest purchase!
« Reply #4939 on: December 05, 2017, 03:22:27 am »
...also bought a Weller Zero Smog TL Kit. It's really silent, features variable fan speed, and the filtering consists of a pre-filter (pink in the fotos) and a HEPA fine part filter. However, the remote switch is a little peculiar: it only works when it is plugged in before switching on the main switch, and then pressing "1" means off and "0" means on.

Any change you can find the P/N of the motor being used in the Weller?  :)
 

Offline G0HZU

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Re: What did you buy today? Post your latest purchase!
« Reply #4940 on: December 05, 2017, 03:36:39 am »
I bought a few things at a large local auction here in the UK and took delivery today. It was an auction for a factory closedown and there were lots of Thurlby PSUs on offer. I got a nearly new PL330D dual programmable supply (32V 3A dual with RS-232 and GPIB) really cheaply, also a Keithley 2000 bench meter and a TTi LD300 load.

https://uk.rs-online.com/web/p/electronic-loads/0535632/

There must have been over a hundred Thurlby PSUs and there were so many they were being sold in lots of 6 or 9 at low prices. But there were a few programmable ones sold separately and I got lucky. I was tempted to buy 20 or 30 more PSUs and sell them on ebay but I don't want the hassle.

So you can expect to see lots and lots of Thurlby dual PSUs appearing on UK ebay in the coming weeks... :)
« Last Edit: December 05, 2017, 03:41:46 am by G0HZU »
 

Offline ChrisLX200

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Re: What did you buy today? Post your latest purchase!
« Reply #4941 on: December 05, 2017, 10:10:12 am »
Bought this 1:5 video distribution amplifier for £2.99 thinking it might be useful for distributing a 10MHz reference from my Racal Rb counter. Well I wasn't going to be losing much if it didn't work  :)  It's basically 50 Ohm but it came with three 75 Ohm terminators as well. Seems to work OK if I put a 10MHz signal through it from my function generator..

 

Offline vk6zgo

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Re: What did you buy today? Post your latest purchase!
« Reply #4942 on: December 05, 2017, 10:35:25 am »
Bought this 1:5 video distribution amplifier for £2.99 thinking it might be useful for distributing a 10MHz reference from my Racal Rb counter. Well I wasn't going to be losing much if it didn't work  :)  It's basically 50 Ohm but it came with three 75 Ohm terminators as well. Seems to work OK if I put a 10MHz signal through it from my function generator..

The standard for video is 75 Ohms, but the mismatch won't be much of a problem.
 

Offline ChrisLX200

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Re: What did you buy today? Post your latest purchase!
« Reply #4943 on: December 05, 2017, 11:14:30 am »
Bought this 1:5 video distribution amplifier for £2.99 thinking it might be useful for distributing a 10MHz reference from my Racal Rb counter. Well I wasn't going to be losing much if it didn't work  :)  It's basically 50 Ohm but it came with three 75 Ohm terminators as well. Seems to work OK if I put a 10MHz signal through it from my function generator..

The standard for video is 75 Ohms, but the mismatch won't be much of a problem.

Yes I know - and I guess the reason why it came with these adapters...

 

Offline Mr. Scram

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Re: What did you buy today? Post your latest purchase!
« Reply #4944 on: December 05, 2017, 11:23:11 am »
Bought this 1:5 video distribution amplifier for £2.99 thinking it might be useful for distributing a 10MHz reference from my Racal Rb counter. Well I wasn't going to be losing much if it didn't work  :)  It's basically 50 Ohm but it came with three 75 Ohm terminators as well. Seems to work OK if I put a 10MHz signal through it from my function generator..
Did you fix the spot on the DMM?
 

Offline Macbeth

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Re: What did you buy today? Post your latest purchase!
« Reply #4945 on: December 05, 2017, 11:36:48 am »
Bought a milligram weighting scale:

It came in a fancy box, with a 5 g and 10 g reference weight as well (the 5 g reference shows 4.999 g and the 10 g reference shows 9.995 g). Needs 2 AAA batteries. I think it is very good quality for the price, I can recommend it if you need such a scale:

http://cgi.ebay.de/132225160852

Does it allow you to use those weights to recalibrate the scale? Also what is it like at the corners rather than the centre? I have 2 scales which are an order of magnitude less sensitive. One of them is great no matter where your load is on its bed, the other gives +/- 2 counts predictably. I obtained the 2x 50g weights separately and used them to recal using the zero and 100g adjustments

But for the price it looks great.

Though sadly this is considered drug paraphernalia by some authorities.
 

Offline MasterTech

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Re: What did you buy today? Post your latest purchase!
« Reply #4946 on: December 05, 2017, 06:09:51 pm »
Bought a 5W blue laser
 

Offline ChrisLX200

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Re: What did you buy today? Post your latest purchase!
« Reply #4947 on: December 05, 2017, 06:16:47 pm »
Bought this 1:5 video distribution amplifier for £2.99 thinking it might be useful for distributing a 10MHz reference from my Racal Rb counter. Well I wasn't going to be losing much if it didn't work  :)  It's basically 50 Ohm but it came with three 75 Ohm terminators as well. Seems to work OK if I put a 10MHz signal through it from my function generator..
Did you fix the spot on the DMM?

Nope - it doesn't show until it's been powered up for an hour or two. If I select inverse display it doesn't show at all. Must be a heat thing I guess..
 

Offline FrankBuss

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Re: What did you buy today? Post your latest purchase!
« Reply #4948 on: December 05, 2017, 08:49:02 pm »
Bought a milligram weighting scale:

It came in a fancy box, with a 5 g and 10 g reference weight as well (the 5 g reference shows 4.999 g and the 10 g reference shows 9.995 g). Needs 2 AAA batteries. I think it is very good quality for the price, I can recommend it if you need such a scale:

http://cgi.ebay.de/132225160852

Does it allow you to use those weights to recalibrate the scale? Also what is it like at the corners rather than the centre? I have 2 scales which are an order of magnitude less sensitive. One of them is great no matter where your load is on its bed, the other gives +/- 2 counts predictably. I obtained the 2x 50g weights separately and used them to recal using the zero and 100g adjustments

The manual doesn't say anything about calibration. 10 g now shows 10.018 when the weight is in the center, and 10.022 when it is over the cylinder at the side which goes into the case. Should be no problem, because the plastic cover can be placed upside down in the center. But looks like +/-0.2% error, because last time it showed 9.995 g, maybe depending on temperature (it is a bit colder here now)? But tricky to measure. Before I cleaned the reference weight of fingerprints with a paper towel, it was 3 mg more, maybe I should use some solvent, and then not touching the weights with bare fingers.

The LED weight is the same, which means the error is relative. Still good for the price, I don't need it very accurate, but was just interested in weighting parts.
So Long, and Thanks for All the Fish
 

Offline Mr. Scram

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Re: What did you buy today? Post your latest purchase!
« Reply #4949 on: December 06, 2017, 04:21:40 pm »
The manual doesn't say anything about calibration. 10 g now shows 10.018 when the weight is in the center, and 10.022 when it is over the cylinder at the side which goes into the case. Should be no problem, because the plastic cover can be placed upside down in the center. But looks like +/-0.2% error, because last time it showed 9.995 g, maybe depending on temperature (it is a bit colder here now)? But tricky to measure. Before I cleaned the reference weight of fingerprints with a paper towel, it was 3 mg more, maybe I should use some solvent, and then not touching the weights with bare fingers.

The LED weight is the same, which means the error is relative. Still good for the price, I don't need it very accurate, but was just interested in weighting parts.
The IPK and its copies change weight due to external influences and tarnishing all the time, which is a problem. They will address these issues by eliminating the IPK as the definition of the kilogram and defining it based on constants instead.

Technically the IPK itself never changes weight, because it is the definition of weight. It's copies do, as they change relative to the IPK.
 


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