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Projects, Designs, and Technical Stuff / Re: Corrosion on DIP pins
« Last post by strawberry on Today at 09:25:15 am »
Not surprising, since the capacitor’s leads have to be made of a material compatible with its own electrolyte!
capacitor leads are tin plated iron (rarely copper)
tin solder tarnish at super high humidity level
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Repair / Re: HP54600B with spike problem with and without signal
« Last post by fmashockie on Today at 09:22:21 am »
It is a private group so you have to request an invite, but you should at least be able to search through chat/forum history before getting approved.  And then you can make posts of your own. https://groups.io/g/HP-Agilent-Keysight-equipment
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Test Equipment / Re: Choosing between entry-level 12-bit DSOs
« Last post by Fungus on Today at 09:21:41 am »
Let me know if you want different parameters than what I've got here:

TSA Ultra set at 800MHz with a 10s 500MHz sweep.

Can the TSA do amplitude modulation?

Put in some AM at about 10% of the frequency.
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Don't have much to add, but +1 to using the implicit modularity of fixed-size (and known size; use inttypes!) unsigneds.

Put another way, it's fixed point 0.16 (or whatever), fractional cycles.

Most anything you would do with degrees, can be done in any other unit.  sin/cos implementations can be adjusted, it's just a matter of changing coefficients and bit shifts, etc.

There's also a... maybe more esoteric route?  Which, I've thought about here and there, but which probably isn't worthwhile for most applications.  In any case, consider the argument of a complex number, which we store as a tuple z = [a, b], which might be char, int, whatever.  If |z| is normalized, we can simply multiply it by any other (complex) number to change the angle -- the basis of the CORDIC algorithm for example.  We trivially extend it into a direction vector, if we're doing something spacial or geometrical -- this can be useful in video games, and I used such a scheme for a raycaster (WOLF3D style) engine way back when* -- but the fact that you're handling ~double the information, that normalization is awkward, etc., means it probably isn't going to be your first pick when you just need an angle.

*The maybe most interesting part here is, the screen vector is automatically scaled for perspective correction -- that is, the vectors cast from camera origin to view plane (well, line), automatically scale the rays cast to walls, giving perspective-correct lengths returned from the "cast" function.  I've seen tons of trig corrections (both preparing the vectors, and correcting the ray lengths), and hackery around singularities (axis aligned vectors), in others' implementations of raycasters, so I felt pretty proud of the general, direction-invariant solution I came up with. :P

Tim
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Repair / Re: E4433B RF sig gen repair
« Last post by microbug on Today at 09:19:49 am »
There aren't any options installed except the high-accuracy timebase (OCXO).

I took some more measurements today. I started with the coherent carrier, and noticed the 2.7GHz signal there as well as the correct signal. This made me suspicious, and I tried the same measurement with the vector output board shield properly installed. The 2.7GHz signal disappeared. If it's coupling into this part of the circuit, it could be coupling into other parts too.

I measured before the I/Q modulator, immediately after, and after the next IC (U80, a 1GG3-4205 RF amp). Screenshots attached.

The following stands out to me:

- Across the I/Q modulator, the signal at the set output frequency loses 30-35dB!
- The gain block U80 appears to be effective only at the set output frequency. The 2.7GHz signal is relatively constant on either side of the gain block.

These measurements were all taken with a piece of coax connected straight to an RF trace, so they won't be very accurate in absolute levels. The very large I/Q modulator losses do seem like a smoking gun suggesting this part needs replacing.

Unfortunately I've damaged a DC block cap again, so need to leave it here for today until I can replace it. I will try bypassing the modulator IC with some coax and a 10dB pad when I've replaced the cap.
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ferrite is made by sintering
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Test Equipment / Re: New Hantek DSO2X1X models?
« Last post by Aldo22 on Today at 09:07:42 am »
I have just learned what the ref save and recall does and was wondering if there was any way to reposition the image or do I continue to setup the trace in the position I want the reference image to be displayed.
The reference waveform is simply a kind of screenshot of a trace. You can't do anything with it other than look at it, afaik.
The “FM” says:

2.9
3. Reference
The scope saves the waveform data in memory in “.ref” format. Up to 9 Ref files (No.1~No.9) can be stored in the internal
memory. The stored Ref can be recalled, a total of 2 Refs can be recalled. At recall, the Refs will be displayed on the screen
directly, at the same time, the time base, volt/div and level position when saving the Refs file are displayed. When the Refs is
not needed, you can select “Close”.
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FPGA / Re: ATF1502 programming & 'wrong' id (fake?)
« Last post by c64 on Today at 09:05:45 am »
Here down under, plenty of cheap computers with parallel port on eBay. Can easily buy relatively modern one (not more than 10 years old) for under $50 AUD
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Beginners / Re: 555 driver and Transformer questions
« Last post by Zero999 on Today at 09:03:40 am »
can you explain to me what to look for in the schematic that shows a strong DC offset?
The current direction through the transformer is always the same, thus the net DC flux in the transformer's core.
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