Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Homebrew Lock-In Amplifier

« Last post by trobbins on Today at 01:19:20 am »

Back in the 90's I used an AD630 to extract a battery impedance measurement from industrial noisy live battery systems using a portable tool that applied about 0.1Arms sinewave into a battery (cell or string) and kelvin probe extracted a signal that was amplified and presented to the AD630.   An ICL8038 sine generator provided reasonable amplitude stability, muting, and a sync signal for the AD630.   The test frequency was aligned to nominal zero-phase shift response of target batteries, and not aligned to any mains related processes.  At that time only a 12-bit ADC was practical, with software flipping the sensed signal polarity and averaging, to achieve a max error tolerance of <0.3% along with temperature errors mainly due to the 8038 and current sense resistor, for FS reading of 50 milliohm and resolution down to single micro-ohm level.  The AD630 was not the main concern for performance, but was a pricey part.

2

Test Equipment / Re: Siglent SDS800X HD Review & Demonstration Thread

« Last post by joeqsmith on Today at 01:14:16 am »

Showing the two peaks closes enough that the readouts will no longer resolve it. 

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Buy/Sell/Wanted / Re: Canceled Because Thread All Shit Up by "tggzzz"

« Last post by schmitt trigger on Today at 01:13:34 am »

Although this forum has an overall laissez-faire attitude, it is far more restrained than other forums which I lurk at.
My personal belief is that real life already has its fair share of stress and complexity, to add a gratuitous quarrel with random strangers.

4

Test Equipment / Re: Siglent SDS800X HD Review & Demonstration Thread

« Last post by joeqsmith on Today at 01:09:35 am »

Channel 1 & 2 fed with a 1MHz 0dBm sinewave.   Math used to add both channels.  FFT then ran on the math channel.  This is about the limit of the old LeCroy.  It can display the separate peaks but the readouts will only display a single peak.  Again, wrong tool for the job but I am curious how well your scopes can resolve two peaks like this.  Feel free to use an external combiner rather than the math. 

5

Beginners / Re: Has anyone been successful selling products?

« Last post by nigelwright7557 on Today at 01:04:19 am »

These days it is very hard to compete with common items.
I find I do better with rarer more specialist stuff.
I can mark up prices a bit more.

Find a niche market to sell in.

6

Test Equipment / Re: Siglent SDS800X HD Review & Demonstration Thread

« Last post by mawyatt on Today at 01:02:51 am »

SDS2000xHD 1MHz -125dBm applied.

2N3055, thanks for doing and posting the measurements.  A couple questions and maybe a request, please, thanks.

1. Why is the amplitude measurement different with the 2kHD vs 3kHD?
2. What happens when you run the modulation test on the 2k?  Similar results but just takes longer to complete?

One is without and other one with modulation. Difference is about 1dB. I'm guessing it's the AWG when modulation got on.. I didn't care because what was important was accurate 6db relation.

On 2k looks pretty much the same and pretty much lasts the same, because at this settings most of the time is acquisitions and averaging not FFT processing time.

The sideband power in each is 1/6 the total (-7.78dB), which leaves the carrier at 2/3 total (-1.76dB), so would expect it to be -6.02dB down from carrier as you've shown.

Your impressive results at this power level with the SDS2000X HD and 3000X HD and followed up by Performa01 with the SDS800X HD

Best,

7

Projects, Designs, and Technical Stuff / Re: Using a current output DAC to control laser diode brightness: which IC to use?

« Last post by LaserSteve on Today at 01:02:37 am »

I'm betting the OP is trying to make a holographic optic or a mask, in which case Op probably should stick to the laser for best spot size

Steve

8

Repair / Re: Can anyone help identify this ON semi IC?

« Last post by CountChocula on Today at 01:01:02 am »

Looks like it could be a MC14001 logic gate (a quad 2-input NAND, to be specific, which is the MC14011B).

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Microcontrollers / Re: It Came from Mainland China: Bootleg MCS-251 "32-Bit 8051"

« Last post by Postal2 on Today at 12:57:53 am »

Most popular chip for Hi-Speed USB is FX2LP. 8051 is inside of it. Any programmer was forced to use it, prefer or not. As a result, 8051 is well-known and easy to program. Example:
https://www.eevblog.com/forum/programming/atmel-maxtouch-bridge/

10

Repair / Re: Tektronix DM501A repair

« Last post by David Hess on Today at 12:54:08 am »

my favorite [...] lubricant

What is your favorite lubricant, David? I assume we're talking about some grease of sorts, not just a thinner agent, such as an oil.

I have had excellent results with MG Chemicals 801B - Super Contact Cleaner With PPE (Polyphenyl Ether).  Its solvent is naphtha which is plastic safe, and the PPE oil does not creep across surfaces unlike silicone oils minimizing contamination.