Recent Posts

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1
Beginners / Re: The importance of eyes fingers and mains
« Last post by Frankje on Today at 05:26:01 AM »
Hi,
I usually start from 0 Volts on the mains input of the smps. I connect the scope on the current measuring resistor at the primary mosfet to check oscillations when cranking up the variac until the oscillations start. Pay attention to ground the scope at live ground !
If they don't start at about 1/4 of the mains voltage, time to check the primary for faulty parts.
When oscillating occurs, I check one of the secondary voltages to see if this stabiles.
If not, check for faulty parts in the feedback loop.
Cracks in solder pads can occur with transformers, heat sink and power transistors.
They might not be visible and you can't measure them. But when high currents flow, they can act as open circuits.
Greetings
2
Thermal Imaging / Re: What was the Flir Lepton 1?
« Last post by Kilrah on Today at 05:24:50 AM »
I have a Lepton that was referred to just as such, with the same source I bought it from later selling Lepton 2... But I can't see a definite difference in the specs.

Maybe they decided to call it 2.0 at some point when they started offering the different lens and shutter options? Although mine has the shutter already, but was probably one of the early ones to have it...
3
Joel,
When I got my scope I checked for new firmware. It showed the latest firmware as 1.203 as of about March 17.
Rob
4
Projects, Designs, and Technical Stuff / Re: NMR Magnet yoke design
« Last post by evb149 on Today at 05:17:26 AM »
Here's a thread where some tips were provided about getting custom laminations made which could be relevant to your needs:
http://www.eevblog.com/forum/projects/inexpensive-standard-or-custom-magnetics-core-laminations-for-diy-projects/new/#new

No particular recommendation just googled for a few terms I previously used for looking for metal and these came up, I haven't used them or seen what they have that is magnet yoke relevant:
https://www.metalsdepot.com/
http://www.onlinemetals.com/
http://www.speedymetals.com/
https://www.metalsupermarkets.com/
https://onlinemetalsupply.com/

Some random talk on DIY NMR:
https://www.thevespiary.org/talk/index.php?topic=12495.0

robrenz is the name of one of the machinists on here that might have suggestions about joining or creating your assembly from a metalworking and mechanical point of view.  He used to post often here...
5
General Chat / Re: How does this forum get so many views per topic?
« Last post by Kilrah on Today at 05:16:04 AM »
Not sure if the forum counts bot reads.
If so, given it's a very active forum in its category it could be indexed more often.
6
I check again Dave video  SDS1kX-E and others video of SDS1kX  on youtube which has different 8" LCD  and does not light the edges.
Yeah, this is definitely a problem with the backlight with reflections in the edges in this 7" LCD.

I got packed  oscilloscope without protective film on lcd and you guys with a protective film or without?

I sent the email to Siglent.eu and I will see what will be the answer.  ;)

No protective film here. Btw, what it can protect... finger print on the glass? Glass surface do not need protective film in such a context.
7
Just wanted to look at the ebay offer posted yesterday and guess what: it's gone
http://www.ebay.com/itm/352040549226
8
If the current requirement is tiny <= 50mA, and moderate price is tolerable, imo LTC3265 does make life easier.  :P

9
As far as I know, the 732B runs a 45°C, it's described somewhere in the manual, I think.
The 5440B at least also keeps its reference ovenized at 50°C, and its resistors at about 55°C, so that the T.C. of the resistors is eliminated, as well as any power dissipation (esp. at 1kV output).

Therefore, the stability is greatly increased, and I don't think, that the drift is greatly enhanced at these temperatures, as resistance wires are much more stable compared to silicon structures, at comparable temperature elevations. Therefore, drift should be < 1ppm/yr. as well.

Compare that to Edwin Pettis' very interesting description of PWW technology.

Frank
10
Awesome! Good to hear.  :-+
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