Recent Posts

1

Power/Renewable Energy/EV's / Re: 5 out of 6 vendors are scamming people with wrong crosssection of cables

« Last post by Bud on Today at 07:14:26 pm »

  A few years ago my 730 pound Miller welder got dumped unto the ground when the frame of my Chinese made 900 pound rated trailer bend under the load and within 30 seconds of placing the welder on it

Must observe the 11th Commandment: "Thou shalt downscale all Chinese specifications by a factor of 2".

2

Test Equipment / Re: TinySA Ultra launched

« Last post by erikka on Today at 07:12:18 pm »

If you need that, you should buy a SG that does a true continuous sweep.

3

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

« Last post by eTobey on Today at 07:11:57 pm »

Please delete your offtopic when you have noted down those details.

You can also use PM instead.

4

General Technical Chat / Re: Russia and China to Build a Nuclear Plant on the Moon.

« Last post by GigaJoe on Today at 07:11:55 pm »

Have some fun ...

A cooling dome on the image at  the first post  ....  in the vacuum ...  is everything all right, I guess so ...

Then ...  each and every nuclear station on earth , fall under basic Carnot Cycle , where active body ,   transfer energy from hot side to the cold side, release energy, that transformed, and then cool down even more for efficiency,  by water or air cooling such as dome ....  That Carnot Cycle give you about 30-40% efficiency ,  the rest dissipated in a thin air. so -  1000 kW electrical nuclear unit about 4200 kW Thermal power, and 3000 kW dissipating as a waste

Space reactors - same principles, atoms divided , emits energy and absorb by active body,  usually liquid metal, then a difference,    instead steam turbine, a thermoelectric generator. due to not much temperature different , overall efficiency quite mediocre ... for 1000W   thermal power probably 70W electrical ....   the rest 900+ watts need to dissipate , usually by emitters, due to vacuum ...
 
technically gases can be used to spin turbines in a space,  Problem A- gas will be lost , need replenish, B- low efficiency due to gas masses,  C- heavy spinning turbine not for a long time. D - everything sealed as part A. E- deal with hot gases , that a headache, metals absorb it and changing internal structure , etc ...

if ...  thermoelectric .... then 40kW electrical transfer to 500 kW thermal ,  and rather heat the core of the moon ,  I have no clue how to dissipate it ...

I think It great, and absolutely doable project, with minimal investment (pen and paper don't cost much), with very solid result ...

5

Test Equipment / Re: SDS800X HD Wanted Features

« Last post by eTobey on Today at 07:10:12 pm »

I wonder how many use these buttons (see picture). You can move the fields by simply dragging them, so i would say these buttons are redundant. They would cover a field that you could otherwise click without moving the fields at all.

6

Beginners / Re: Checking for noise in resistors

« Last post by TimFox on Today at 07:09:03 pm »

The T3 in noise mode is described in its manual, available online.
It applies something like +125 V through a current limiting resistor and amplifies the resulting audio through a high gain tube amp to allow listening for snap-crackle-pop noise.
The LM386 suggestion is a reasonable alternative for the 12SH7, but probably less bulletproof.

7

Test Equipment / Re: TinySA Ultra launched

« Last post by shapirus on Today at 07:07:28 pm »

Please explain why it should be fixed, except for cosmetic reasons when observing with a DSO?

It may be important in any practical application where a frequency sweep signal is used and it's expected that the signal won't contain any frequencies outside of those expected at any given time in the sweep range.

I'm not sure what those would be, I dont have any examples of my own.

8

Beginners / Re: Checking for noise in resistors

« Last post by floobydust on Today at 06:59:42 pm »

From the era of tube gear, many signal tracers have a "NOISE" mode switch built-in. Example Heathkit IT-12.
That applies high voltage bias to the probe about 115VDC/1.7mA and with the audio amplifier you can listen to the result.
A noisy resistor or capacitor with bad dielectric can be flushed out. It was a common problem in the day.

Yeah, that and the more capable T-3 are the Heathkit units I talked about in a previous post in this thread. It is unobtainium here in Europe at least at a reasonable price.
That was more or less the circuit I was trying to make, albeit somewhat modernized, i.e.: no tubes 

It's not hard- take an LM386 amplifier board $1.50 and run that with added blocking cap+protection diodes, and low noise HV power supply.

9

Power/Renewable Energy/EV's / Re: 5 out of 6 vendors are scamming people with wrong crosssection of cables

« Last post by Karel on Today at 06:59:10 pm »

Still my question is unanswered:
Have you ever checked on the cross section?

No, because I order from Digikey/Mouser/Farnell.

10

Repair / Re: LED Strip lights flashing like a bad 90s rave

« Last post by floobydust on Today at 06:58:23 pm »

If the LED string goes open-circuit, due to thermal expansion on the bonding wires/die attach, the PSU output voltage can rise up - and when the LED cools off and reconnects, the filter caps discharge hard into the string. So, I have seen blinking LED strings with many failed elements when I was thinking it would be just one LED failing.

The small capacitor by J3 is critical for the SMPS IC"s operation. Make sure its ESR is good as well as capacitance. These are 22-47uF 50V parts.