Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Vacuum Fluorescent Display Driver

« Last post by bostonman on Today at 01:15:53 am »

After building a voltage divider and setting up for measuring with the logic analyzer, I finally had time earlier, however, I think more questions than answers came out of it.

My logic analyzer is 16-channels, but the chip has seventeen outputs (not including two additional outputs for decimal places). I made the error of accidentally connecting one of my logic analyzer channels to DP2 meaning two of my logic analyzer channels weren't connected to two of the SEG outputs (one accidentally connected to DP2 and unable to connect to the seventeenth data line due to my logic analyzer being sixteen channels).

The logic analyzer results was not what I expected. Attached are four CSV files (they may not be worth assembling to show the logic because it contains many data points). The CSV files are named accordingly and I'll also upload some pictures of the display which will show the display at the time of the logic analyzer capture (give me a few minutes).

The reason the results weren't as expected: if I kept the logic analyzer set to keep polling, the pulses changed. I expected different because when the display showed (as in one file) all 1's and I removed the input so the display remained frozen, the logic analyzer (as I expected) shouldn't show different pulses each time it polled.

If the entire display is twelve digits, and each digit has fourteen (?) segments, and two decimal places, that uses sixteen out of the seventeen data lines (not sure where the seventeenth is used). The G lines are twelve total (for twelve digits?).

Due to the display having 'period', 'frequency', 'ch1', etc... and assuming each G line is for each digit, that leaves the question of how does the other stuff get lit? My guess is that more than one G line is on so the data lights MHz, CH1, etc...

Unfortunately I didn't have time to investigate this. If my assumption is wrong, then I should see the logic analyzer output to have each channel in sequential order (or no two G lines on simultaneously).

Due to the complexity of trying to not damage anything, I'm close to pulling the trigger and just swapping the IC.

2

Programming / Re: Linux Dependency Black Hole

« Last post by linux-works on Today at 01:12:13 am »

appImage is a large image but it WORKS and that's great. for many products, I do just take the easy way out and do the app image thing.  cura is one of them and open-scad is another.  both too large and hard to build/install so I just take the appimage route.  its not ideal but it works.

3

Repair / Re: TEK TPS2000 series scope fault issue

« Last post by trobbins on Today at 01:10:25 am »

lern01, I looked at other photos I took, but can only discern the National Semiconductor logo on U1701 IC, and not the part model.  I'm not in a position to open up the scope to look further, as the original fault may return (to date the scope is still working ok).
Regards, Tim

4

Programming / Re: Linux Dependency Black Hole

« Last post by ataradov on Today at 01:06:09 am »

I don't take it emotionally. I don't really care what you do to your system. But what bothers me is when people go on the forums and complain that "Linux sux" when they mangled their system by installing random stuff from tar.gz.

Installing into "~" is fine. Installing into "/" is just asking for trouble.

But it also depends on the type of a system. If this is some random RPi that can be re-imaged when necessary, then who cares. If this is your primary system, not destroying it is a good call.

5

Programming / Re: Linux Dependency Black Hole

« Last post by mag_therm on Today at 12:58:48 am »

Well I have built stuff from tar.gz, in fact recently too on two for the SDR.
Always in the ~ as I recall.
I presume many others around the world have too.

And please don't take all this so emotionally, its only a hobby for me.

6

Test Equipment / Re: SDS800X HD Bug Reports + Firmware

« Last post by electronics hobbyist on Today at 12:58:17 am »

I found a bug:
When adjusting the level for source A in "trigger delay", and setting it below low level of signal, acquire stops. At 50% level it triggers kind of slow, but below the rate increases, but then eventually stops completely. The trigger does not restart after moving it back.

This problem is related to the signal. It requires that the signal of both channels is above or below zero level. Added to Bug No.15.

7

Test Equipment / Re: SDS800X HD Bug Reports + Firmware

« Last post by electronics hobbyist on Today at 12:52:14 am »

The setting of the trigger type edge influences the qualified trigger. In the first part of the video the trigger is not exactly stable, only if the slope of edge trigger is changed, the qualified triggers works without issues.

These two issues look the same and have been added to Bug No.14.

https://www.eevblog.com/forum/testgear/sds800x-hd-featureimprovment-disscusions/msg5459225/#msg5459225

8

Beginners / Re: Replacing SRAM IC with Flash

« Last post by Nominal Animal on Today at 12:48:28 am »

How about using 512k×8 low-power SRAM like CY62148ESL-55ZAXI, and controlling the four highest address bits (A15, A16, A17, A18) with a 16-position absolute encoder and four pull-up resistors?  With a pull-up on /CE, the stand-by current draw is just 2.5µA typical, max. 7µA, and voltage can be 2.2V–3.6V or 4.5V–5.5V.  That is, you can use 2.2V – 3.6V battery backup voltage.   Since LH52256C/CH uses 5V logic, the battery vs. normal operation voltage selection should be easy (higher voltage wins).

You'd get sixteen banks in a single pak, selectable using an absolute rotary encoder.

9

Beginners / Re: CR6842S ACDC HELP

« Last post by floobydust on Today at 12:44:49 am »

If current-sense resistor R7 goes open, this is usually because it's a fusible/flameproof part that got overloaded from a mosfet shorting out. It damages the IC and new mosfet if you are not careful to check those parts too.
A dim light-bulb tester to power this is also a good idea to save on fuses and smoke. Even a 25W lamp is all you need to power it up with no load.

10

Repair / Re: Ksger T12 Sudden Death

« Last post by floobydust on Today at 12:39:26 am »

It badly needs heatsinking. The new part will roast and fail too, guaranteed.
Most controllers use SOT-223 Vregs, SOT-89 is pretty hard to cool with no copper pour on the tab like on this lemon control board. As long as 25Vin is not too much.

Russians some put in big copper wire loop soldered to the tab to make a heatsink, others lowered the input voltage adding a pre-regulator like 7805T+output capacitor by cutting the trace and adding wire jumper from the control board to the added Vreg tacked on the PSU somewhere.

To use just one IC, tack soldering a 7833T sticking up in the air would work.