Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Accurate sine wave in terms of amplitude

« Last post by sw_guy on Today at 03:29:54 pm »

Generating a precise & stable amplitude (and frequency) square-wave isn't difficult, see below.
However extracting a precise & stable sine-wave from this square-wave may be more difficult than expected.

Fully agree and I am aware of that. Since the frequency is fixed as well as the amplitude, that might be doable well enough. I have to do some testing and thank you for everyone about ideas and considerations.

What could be a proved single opamp for a wien oscillator?

2

Beginners / Re: What function generator, that does a bit more than just a simple signal

« Last post by shapirus on Today at 03:21:07 pm »

JDS2800 can't do AM/FM btw, so look elsewhere if you need that.

PWM single pulse deviations, not via its standard means, either.

Introducing spikes, probably yes, by creating a respective wave on second channel and then combining them externally.

Or maybe it's possible using arbitrary waveform, but I've never tried that.

3

Test Equipment / Re: TinySA Ultra launched

« Last post by shapirus on Today at 03:16:09 pm »

More like a cosmetic issue, having all those random waveforms displayed between steps, especially since it's not the primary function of this device.

It would be nice if it could be fixed without compromising other functionality, but otherwise no big deal.

4

Beginners / Re: LC filtering for combined Vref/VDD of ADC

« Last post by temperance on Today at 03:14:55 pm »

Bonus: LDO at least gives [the chance for a] more accurate supply/ref, potentially reducing calibration error.

My posts suggests the use of a shunt reference instead of an LDO which is a better option if power loss is not an issue. It doesn't suffer from reduced PSSR when operating close to Vin like the LDO.

5

Computers / Format a 256GB pendrive with FAT32 using a windows 10 pc

« Last post by Karel on Today at 03:14:27 pm »

A friend bought a new usb pendrive with a capacity of 256GB.
It worked fine with his windows 10 pc but his DVB-T decoder with usb slot (used to record tv-programs)
did not recognize the pendrive.
Apparently the decoder accepts only pendrives formatted with FAT32 but our pendrive was formatted with exFAT,
so we used windows 10 to format the pendrive with FAT32.

Then we discovered that windows refuses to format a pendrive with FAT32 when the volume is more than 32GB 

I took his pendrive home and used my Linux machine to format the pendrive with FAT32. Problem solved.

Morale:

Linux is a system of possibilities.
Windows is a system of limitations.

6

Repair / Help needed identifying a Zener/TVS Diode (Toyota ECU)

« Last post by Signal Simon on Today at 03:11:18 pm »

I'm attempting to repair a Toyota engine ECU that it seems has had an over-voltage event, possibly failed alternator or loose battery terminal.
I have found two failed diodes, D401 and D402 (Shorted) marked "1E 8D" which just seem like series diodes from the main power supplies, so have fitted 1N4002s in their place.
However my mystery is D404.
From the screen print, it's a Zener and is directly across the internal supply.
One of its circuit tracks has blown open, so there was obviously more than just a bit of a transient.

The diode is marked: T S5225 8.C

The T I'm assuming signifies Toshiba.
It's in a substantial case 10mm diameter and 4mm thick, similar to a Motorola MR751 series.
Can't find any reference online, it obviously isn't a 1N5225

Logic says the Zener(TVS?) voltage should be in the region of 18 to 24Volts

Any help appreciated

Thanks,
Simon.

7

Test Equipment / Re: Siglent SSA 3021X... Ooops

« Last post by Joel_l on Today at 03:10:33 pm »

Something very strange happened.

It occurred to me that I do have a better way to check the input impedance of my SA, I can use my antenna analyzer ( at least for a limited range ).

I hooked it up and did a sweep around 20MHz, it showed me an SWR off the scale. I wanted to see what the impedance looked like so I switched it to do a Smith chart. When I did the sweep, the SA barked at me with an overload. I went and changed the attenuation did a few more sweeps and things looked good. Went back to do a SWR sweep and it looked good 1.2:1.

I disconnected the antenna analyzer and hooked my TX back up and it worked just fine, no more high SWR warning.

I need to look at this more and make sure I'm not chasing bad data.

8

Repair / Re: Precision Standards AC-DC Differential Voltmeter 360A - manual

« Last post by calin on Today at 03:09:26 pm »

Does look like working / turning on somewhat without releasing any magic smoke. But that's about it, the dial indicator just sticks to the max when I try to measure anything  and that is it.
I am a tad weary sticking my fingers too much in, when this thing is running, as it does produces internally some high tensions especially on the higher ranges.
At worst I can gather some really nice precision resistors from the innards and end up with a nice project box if nothing better comes out of it

9

Test Equipment / Re: TinySA Ultra launched

« Last post by KungFuJosh on Today at 03:08:48 pm »

For me, just curiosity.

10

Beginners / Re: Convert US standard 115V to International 230V

« Last post by Zero999 on Today at 03:08:05 pm »

If the circuitry after the capacitor has no problem with the voltage dips between refreshes from 120 V 60 Hz supply, there will be plenty of headroom for the slightly deeper dips when the supply is 230V 50Hz.

That's too bad if the capacitor and switching regulator are only rated to 200v.