Recent Posts

1

Buy/Sell/Wanted / Re: SALE (AU/NZ): Multicomp Pro MP710086 (Owon P4305 rebadge) at element14

« Last post by EvgenyG on Today at 12:13:38 am »

I will wait for another mark down, I think there will be more. If they go to $100-$120 mark, I'll get one for myself too.
The PSUs are selling fast now as they've discounted those to ridiculous prices. $31 bucks for a basic linear PSU? Unseen.
Also cheap are multimeters, but I already have too many. Test leads some are like 70c, bought a few, could not walk past.
Weller station yep same here I don't need a 3rd soldering iron lol

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Power/Renewable Energy/EV's / Re: Flyback controller output voltage and amps under load

« Last post by thomasx on Today at 12:10:22 am »

Some improvements, I am now "only" down 2,5V at max load, 7A, from 12.2 to 9.7.

Looking at figure 9.21 in page 40 of the datasheet, it shows about 1 volt drop at a step to full load, (16V, 2.5A, 40W in that design).



So question is, should I also expect to get to a 1V drop at full load, or is 2.5V drop what I can expect as best in this case, with a 12V, 7A, 84 W converter?

Getting 9.7 volt from a 12 V supply just doesn't feel ok. Sure, I can up the low-load voltage to 13V and end up at 10.5V at full load, but it still doesn't feel good enough.

https://www.ti.com/lit/ds/symlink/ucc28c54-q1.pdf?ts=1714685064113&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FUCC28C54-Q1

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RF, Microwave, Ham Radio / Re: Generate FM using IQ inputs?

« Last post by radiolistener on Today at 12:06:22 am »

scale depends on audio sample range.
sin/cos functions already can handle any angle, but if your implementation don't know how to wrap it, you're needs to do it manually.

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General Technical Chat / Re: Silicone vs. PVC measuring leads

« Last post by tooki on Today at 12:02:56 am »

Finely stranded? Easy. Really finely stranded? I have never seen it in PTFE.

For example, for 24AWG/0.25mm2:
Regular stranded: 7 strands
Fine stranded: 19 strands
Very fine:~ 40 strands
“Really fine”: ~65-130 strands.

There’s simply not much point in the higher strand counts because their flexibility is lost on the PTFE. 19-strand 24AWG PTFE is readily available, but I’ve never seen or heard of finer ones.

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RF, Microwave, Ham Radio / Re: BFU590G Troubles

« Last post by profdc9 on Yesterday at 11:58:07 pm »

For common-base/common-gate (CB/CG) and common-collector/common-drain amplifiers (CC/CD), you have to be careful about preventing oscillations.

The junction capacitance of the base/gate and emitter/source and lead inductance can form a series LC circuit that causes the voltage on the base/gate to oscillate. 

A good way to minimize this is to ensure that the capacitor that grounds the base/gate (CB/CG) or collector/drain (CC/CD) (depending on configuration) has as short of leads or connection as possible between the ground and base/gate (CB/CG) or collector/drain (CC/CD)  Also, a small damping resistor, say 10 ohms or so, can be placed in series with the emitter/source (CB/CG) or the base/gate (CC/CD) with as short of a lead as possible as well, as stray capacitance from the lead to the ground plane can also be a source of oscillation.   The components on the side of the base/gate and collector/drain should be as separated as possible (180 degrees apart) as to not couple together if possible.

Similarly, for common emitter or common source, the emitter/source lead should be as short as possible and connected to the ground plane as closely as possible.

In some cases, even vias, which can have an inductance of 1 nH or even more, can be too much.  Using many vias in parallel and a larger area of the top of the board for ground helps reduce the inductance.  In extreme cases, you might have to think about using structures such as radial stubs around the leads to create a ground point at the lead as well.

6

EEVblog Specific / Re: EEVbog 1613 -Audiophile REPAIR: Chord Hugo DAC

« Last post by EEVblog on Yesterday at 11:40:12 pm »

I think i know why the battery was acting weird:

You damaged the insulation on the battery negative cable close to the wifi module when you used the yellow plastic spatula at 10:20 in the video.
I have a big screen and can see individual strands of silver wire starting at 10:46.

It also looks like you damaged the insulation on the positive wire when you pinned it down with the tweezers at 11:17, i can see a silver spot in the middle of the cable at 10:22.
While doing this you might also have produced a short between the positive wire and the through hole pad below it, which would have triggered the protection circuit. After you let go of the wire the short was removed and the battery protection circuit could recover.

At 12:15 i can count three strands of wire in the negative cable, i attached a zoomed in screenshot to this post.
I can also see some silver in the red cable.

I was puzzled that he took out the batteries and then desoldered, but put the batteries in before soldering the contacts. I would have soldered the contacts with the batteries out, giving me lots of room, and then slipped them into place.

To be fair, if you solder with batteries outside, you then may find that wires are of the wrong length or you need to bend them awkwardly.

Correct. I've bene burned by this too many times, so it's just a habbit to fit first then solder.

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Projects, Designs, and Technical Stuff / Re: Lithium Ion (Pouch) battery - Over/Under voltage charge protection

« Last post by uer166 on Yesterday at 11:39:47 pm »

A protection circuit is not a charger, and it is not fine to use it as such.

Those BMS ICs trigger after over voltage already happened to a certain extent, so use a proper charging system for the cell.

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Projects, Designs, and Technical Stuff / Re: Distance sensor required with 0.1mm accuracy and upto 4m range

« Last post by David Hess on Yesterday at 11:39:35 pm »

Get a scale for a DRO.  They come in magnetic and optical versions.  The advantage of the magnetic versions is that you can cut the scale to length.

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EEVblog Specific / Re: EEVbog 1613 -Audiophile REPAIR: Chord Hugo DAC

« Last post by EEVblog on Yesterday at 11:39:10 pm »

How did the neighbour react to being considered an audiofool?

He also thinks they are stupidly expensive, hence why he got it cheap 2nd hand.

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Projects, Designs, and Technical Stuff / Re: Lithium Ion (Pouch) battery - Over/Under voltage charge protection

« Last post by Mr.B on Yesterday at 11:38:41 pm »

The protection circuit is just that – a protection circuit.
You should not be using it as a charge management circuit.
You would be well advised to use a proper charge management chip for LiPo batteries.
They are readily available and cheap.

Edit to add: And always purchase your LiPo batteries with the built in protection circuit as well as adding your own proper charge management.