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Apparently there are 4 dual TVS diodes under HDMI connector. If you are lucky, one of them is faulty and IC remains intact. If you find one which has one of the side pins shorted to center pin, you can simply desolder it and check resistance again. If resistance is fine, then you could attach monitor and check again. If everything is fine, it would be the best to replace TVS but it will work without it. Just those pins no longer would have protection.

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Thermal Imaging / Re: Thermal eye 4500, 3600AS
« Last post by oddbondboris on Today at 01:37:14 pm »
so i did some digging attached are a couple of very rough python scripts and the start of a library of sorts
also tossed in all the docs i have

usbobj.py is the start of the library << this isn't that terribly coded
the next three are abandoned code that is just terrible looking
usbframe.py makes a png capture over usb
usbfun.py sends commands to the camera
usbfun2.py is a fuzzer of sorts from what i can see. you probably shouldn't run it

i know when the camera bricked i saved the entire terminal buffer somewhere but i can't seem to find it

syntax for usbfun.py i remember as being ./usbfun.py <command> <parameters>  i added it at the top of the file


all the scripts assume your camera conforms to the usb api pdf that has the camera at address 2
the spare board i found had the address set to 1 but also had all sorts of other quirks

basically the only thing you should really use this for is to see how libusb works in python and how the packets are structured.

also attached the one image that survived my stupid script that overwrote the previous image.


icd is the usb interface specification
36-46Expansion_port_supplement.pdf are the docs for the expansion interface
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I was trying the Mega328PB and interrupt-driven tachometer for the fan and then I thought why not just use a Arduino Nano and then the project was all over the place.
What sections would you like to look at, I can dig for that.
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Beginners / Re: Linear PSU with modern components, will it matter ?
« Last post by David Hess on Today at 01:34:28 pm »
I would say that error amplifiers peaked not long after the OP-07 and similar parts.  Once  you get to 100nV/C of offset drift, chopper stabilized amplifiers do not help much in a large design because external thermocouple effects.  Even in the 1970s there were parts almost that good.  I have made some incredibly accurate power supplies with parts like the LT1007 and OP-27 taking advantage of their low input noise and high open loop gain.

Ring emitter bipolar transistors for low noise and fast response have been around almost as long.  Power MOSFETs are faster if you drive them hard enough but also higher noise.

There are more precision references available now but I think the availability of precision resistors has had a greater effect.  I think there was a better selection of good potentiometers in the past though.

So to sum up my thoughts, I think the design and implementation has been more important than the parts since the 1970s.
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Anyway, do you have hot air station? Without it it's not possible to replace faulty IC.
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its a "no-brand"  Bay Trail Intel Celeron Quad Core N2920
Then it's not NUC.
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Beginners / Re: Isolation transformer and electrons
« Last post by IanB on Today at 01:29:09 pm »
There is one case where constant current circuits have been used, and that is lighting circuits. In particular, street lighting (in the past), and airfield lighting (maybe still today).

In the case of street lighting there would be one long loop containing many lamps in series, and a constant current power supply designed for a specified current with a large compliance voltage (maybe 1000's of volts). Each lamp used in such a circuit is specified with two numbers: the rated current, and the output lumens.

Because the lamps are in series, there are certain challenges with this system. For instance, if a bulb blows it will break the circuit and all lights will go out. Unfortunately, if a bulb blows the full compliance voltage will also appear across the break in the circuit, leading to a bright, hot arc with lots of smoke, flames and molten metal. Therefore each bulb has a special bypass link that fuses and shorts out the bulb if it blows, preventing the arc and keeping the other bulbs lit.

Why might such an awkward arrangement be used? Presumably because it lowers the wiring cost and also because keeps all bulbs at the specified brightness. There is no issue of a bulb at the end of a long wiring run being dim due to voltage drop in the cable. Every lamp will give the specified brightness no matter how far away from the power source. This might be an advantage on an airfield where every lamp must perform exactly to specification.

The wiring cost would be lower because 50 bulbs use the same current as 1 bulb, and therefore you don't need fatter cables to carry 50x the current.
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Test Equipment / Re: DL3021 won't import the CSV
« Last post by v8dave on Today at 01:28:34 pm »
I figured it out. It requires a TAB character in front of each value. Using tab delimiter format from Excel doesn't work.

You have to manually edit the CSV file after you export it. Lucky my table wasn't too large. :(

Code: [Select]
Step, Mode, Range, Value(A), Time(s), Slew(A/us),
1, CC, 4A, 0.02, 30, 0.1,
2, CC, 4A, 0.15, 1, 0.1,
3, CC, 4A, 0.02, 0.5, 0.1,
4, CC, 4A, 0.15, 1, 0.1,
5, CC, 4A, 0.02, 0.5, 0.1,
6, CC, 4A, 0.15, 1, 0.1,
7, CC, 4A, 0.02, 0.5, 0.1,
8, CC, 4A, 0.15, 1, 0.1,
9, CC, 4A, 0.02, 0.5, 0.1,
10, CC, 4A, 0.15, 1, 0.1,
11, CC, 4A, 0.02, 0.5, 0.1,
12, CC, 4A, 0.15, 1, 0.1,
13, CC, 4A, 0.02, 0.5, 0.1,
14, CC, 4A, 0.15, 1, 0.1,
15, CC, 4A, 0.02, 0.5, 0.1,
16, CC, 4A, 0.15, 1, 0.1,
17, CC, 4A, 0.02, 0.5, 0.1,
18, CC, 4A, 0.15, 1, 0.1,
19, CC, 4A, 0.02, 0.5, 0.1,
20, CC, 4A, 0.15, 1, 0.1,
21, CC, 4A, 0.02, 0.5, 0.1,
22, CC, 4A, 0.15, 1, 0.1,
23, CC, 4A, 0.02, 0.5, 0.1,
24, CC, 4A, 0.15, 1, 0.1,
25, CC, 4A, 0.02, 0.5, 0.1,
26, CC, 4A, 0.15, 1, 0.1,
27, CC, 4A, 0.02, 0.5, 0.1,
28, CC, 4A, 0.15, 1, 0.1,
29, CC, 4A, 0.02, 0.5, 0.1,
30, CC, 4A, 0.15, 1, 0.1,
31, CC, 4A, 0.02, 300, 0.1,
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its a "no-brand"  Bay Trail Intel Celeron Quad Core N2920
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I don't see a big difference between the LM317HV and TL783 circuits here. Both are a linear HV regulator so heat is a big concern.
The TL783 circuit 120V zener just means most of the heat will instead be dissipated by the TL783 now. The TIP150 drops voltage when things are over 120V input-output. It's also a small, obsolete  transistor compared to MJH11022.
The LM317 circuit was the opposite with the 6V zener, it let the MJH11022 dissipate all the heat in dropping the voltage down.
Check the thermal calcs, 1A output and 140VDC input is still 15W of heat and a large heatsink for that to rise say 30-40C.

I still question the need for a voltage regulator with solenoid loads. They can take +/-20% variation and a decent sized power transformer will "regulate" close to that. What's wrong with using a 90VAC transformer and bridge rectifier only. I find 125VDC is only used in railroad and utility substation applications.

Note also there is a liability due to the shock hazard with the high voltage going outside the product.
I would increase the safety of the output connectors and field wiring. Make them touch safe at least.
Banana plugs might not be insulated well enough for lay people to mess with them.
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