Recent Posts

1

Beginners / Re: LM324 Power Supply with variable voltage and current

« Last post by xavier60 on Today at 04:19:17 pm »

Do you mean that I need a separate winding on the transformer or another small transformer for the DVM and tap changer ?

That can be ambiguous, you can have the same winding or transformer for the tap changer and DVM but separate to powering the LM327.

2

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

« Last post by radiolistener on Today at 04:17:15 pm »

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

Can you please check if my tool to read/write arb waveform for PSG9080 works with JDS2800?

just connect it to PC and try to execute:

Code: [Select]

PSG9080_ARB.exe COM3 -read 1 wave01.txt

where COM3 is a port which appears when you connect signal generator to PC.

It should read arb wavform 1 from generator to "wave01.txt" file

3

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

« Last post by Monkeh on Today at 04:14:27 pm »

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

Self-imposed limitations. Windows provides a tool for formatting drives. It is not the only one you can use.

4

Repair / Re: dana exact model 170 amplifier: looking for manual/schematic

« Last post by TerrySt on Today at 04:14:20 pm »

I know this is an old thread, but while looking for something else, I found a copy of the manual for the Exact 170 Amplifier.  Unfortunately, it is a very light copy, but is still (barely) readable.  I'll attach a pdf in case someone is looking for it.  If anyone knows of a better place to upload it, feel free of course.

Terry

5

Beginners / Re: LM317 Based Digitally Controlled Power Supply

« Last post by MrAl on Today at 04:09:03 pm »

The LM317 when used as the regulator is not very accurate. This starts with the output pins / contacts and the heating of the reference and amplifier part. So a serate build regulator is often the more accurate way. Adding current limiting / regulator to a LM317 regualtor circuit is challanging, arguably more tricky than starting from scratch with OPs and power transistors.

Usually the regulation is done analog - a digital solution is rather demanding on the ADC / DAC side and still often slow.
When starting with PWM as a set signal one goes PWM -> fitler to get an analog set voltage and than goes with an analog regulator (e.g. classic PID style) from there.

Hi,

Yes, they do not mention that directly in the data sheet so it's easy to miss.  If you look at the spec's carefully and surmise yourself that the temperature is going to rise with significant load in most cases, then you might realize that the on-chip voltage reference temperature is also going to rise and thus the output voltage will change more significanly than the voltage reference.

6

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

« Last post by ejeffrey on Today at 04:08:57 pm »

What kind of cables?  Power or signal?  Were they advertised to conform to a particular industry spec or just a specific size?

 

7

Beginners / Re: How Current Limitation is happening in the circuit???

« Last post by MrAl on Today at 04:05:34 pm »

Hello All,

I started constructing prototype of the below circuit, But 68ohm,2Watts resistance went to breakdown.
again i changed to 470ohm,2Watts , again it started smoking.


I also changed the MJE2955, but 470 ohm started smoking, What is the problem in the circuit?

How to find my transistor has went to breakdown?

Thank you all.

Hello there,

You are probably going to have to learn to troubleshoot these circuits yourself.  That means making measurements with different loads, and possibly running the input voltage up a little at a time to see when the power dissipation starts to get too high in the resistor(s).  You keep having this same problem with just about every circuit you work on like this.  A resistor smokes in every circuit you posted so far.
To find out the problem you often have to take voltage and/or current measurements before anything smokes, and that means possibly with a light load and slowly increasing that load.  If it happens even with light load, then you might have to turn the input voltage up slowly until the problem shows itself but does not blow anything out.

So to start see if it runs with no load.  You don't seem to say what the load is when this happens, or even if there is a load or not.

8

General Technical Chat / Re: Harmonised technical standards to be publicly available in EU

« Last post by Monkeh on Today at 04:04:54 pm »

Who needs them?

Interesting,the short form link didnt make that clear. As  tom66 says it would be nice if british standards were to follow suit, little chance of that happening.

Who needs them, unless you're still using Whitworth threads and measuring speed in furlongs-per-fortnight.

That was just Benta taking a cheap shot at British Standards, not questioning the need for standards. Of course, he's likely never read any British Standards, nor is he aware how many of them drive ISO and IEC standards..

9

Projects, Designs, and Technical Stuff / Re: (Yet Another) DIY Multislope ADC

« Last post by Kleinstein on Today at 04:02:19 pm »

The crystal clock jitter is usually on the order of 1 ps RMS. So the measured 50 ps are most likely mostly from the PLL.  This number also makes sense - it is about what the STM32G071 datasheet gives for a different µC with internal PLL. Jitter is usually not 100% white phase noise, but may have some extra lower frequency component. So when the clock is divided down (even with an ideal divider) the period jitter can go up. For the mudulation patter (some 5-20µs period) the effective noise could be a littler higher than the period jittter.

The noise added from jitter is about RMS jitter divided by the integration time times the reference strenght times the square root of the number of ref. switching events. As a number example maybe 50 ps / 20 ms * 28 V * sqrt(4000) = 4.4 µV rms.

50 ps jitter would add a noticeable noise source to the ADC, especially when using relatively fast modulation. It could still be OK for the 6-7 digit range. For lower noise one would likely need external synchronization directly to a stable clock. This could bring the jitter down to the 1-3 ps range.

10

Beginners / Re: Comparator circuit seems to be oscillating (well, pulsing, really). Solutions?

« Last post by MrAl on Today at 03:58:11 pm »

How about an actual schematic instead of vague blurb?

This thread has been hijacked.  The original thread had no relation to this new topic and was a few years ago.