Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Reducing ESP32-S3 current peaks during WiFi

« Last post by lutkeveld on Today at 11:31:12 am »

The ESP32 has indeed high current peaks. I don't think just a buck converters and regular capacitors are really going to solve the problem. The impedance of the P1 port's power supply is going to be ballpark lower than your capacitor, so it's going to try to supply this power.
You can go a few ways, basically you need to set a current limit lower. You can have a current limited boost converter go to let's say 24V and run an unlimited buck converter from that.
Or you can charge a capacitor, 5V with the P1 port, current limited, and have a buck-boost instead of a buck for the ESP32. This current limit can be as simple as a resistor. Maybe even a supercapacitor could work, something like 1F has plenty of energy to cover high current peaks and it's not as expensive as it sounds.

That is also what I am suspecting, because without a current limiter the peak only goes away to a certain extent when increase capacitance to quite high values, indicating it's still supplied by the P1 port. 1F would be quite bulky / costly, so trying to avoid that.

---------------------

I'm curious how far I could get by just buck IC selection and tweaking the output LC. Maybe have to get some SPICE going to see its effects.
Increasing the input capacitor can only be done to a certain extent before I need to add a current limiter for inrush anyway.
At that point, something like a AP22652 might work, although for a guaranteed max 250mA limit, the minimum limit will be ~180mA due to accuracy.
Will have to check if the baseline current of the ESP32 never gets that high, otherwise it will get clamped.

2

Test Equipment / Re: OWON OWH9811 (1 phase) and OWH9830 (3 phase) AC Power meter

« Last post by flash2b on Today at 11:26:05 am »

I am working a  definition for TestController and started from the SCPI manual. I have already connection and can read values. I will focus on normal power management functions first and then preceding to Harmonics.

If the SCPI proves to be a limitation, I will use the Modbus RTU instead if that is better suited or quicker.

If there are people interested to beta test, please let me know.

3

Beginners / Re: Just a try with an old amp

« Last post by Terry Bites on Today at 11:23:06 am »

I think that what you have experienced "dielectric reforming", caps coming back from the dead.
I'd never depend on that lasting.

If you are determined to go down the old new stock path, then put the caps on a power supply and soak them at their rated voltage for a day or so.
Or as far as your psu can get near.

Check them with an LCR meter if you have one. Even a cheap one (apologies to Lord Carlson) say, the  Fasizi Transistor Multifunctional Tester  Tester from amazon. Under €20

Old caps suck, they were never intended for long life applications.
I'd replace them with new. Replace all the elco's the amp. For a full restoration consider replacing very cap!

A quick look on Mouser shows that even top notch Nichon 3300u/50beoordeling are only a few bucks.
You can get a much better price on LCSC of course. https://www.lcsc.com/

I doubt that a filter cap value is that critical.
Moving up to a higher and more common value should be fine. Say 4700u/50
More modern caps are usually physically smaller than their older counterparts and usually fit in with space to spare.

4

RF, Microwave, Ham Radio / Re: Transistor for 2.45 GHz Power Amplifier

« Last post by dietert1 on Today at 11:22:42 am »

When i look up digikey they list 32 bipolar transistors in the 1 .. 2 W range with 6-8 GHz transition frquency. Three are in stock: 2SC3357, 2SC4703-T1-AZ and NE85634-T1-RE-A. Didn't research their datsheets nor simulation models but i'd guess any one of them should serve.
They also list higher frequency transistors, yet without stock, except the BFP490E6327. That one is 4.5 V and fT = 17.5 GHz.
Anyway, it can be more educational to make an amplfier with parts close to their limits.

Regards, Dieter

5

Buy/Sell/Wanted / Re: 12-Year-Old hobbyist Designed my first schematic, hoping for surplus lab tools

« Last post by watchmaker on Today at 11:19:00 am »

Good on ya.

Participate in the Beginners subForum and you will learn much.

Regards,

Dewey

6

Test Equipment / Re: Siglent SDS800X HD 12 bit DSO's

« Last post by watchmaker on Today at 11:14:22 am »

It's always a combination. Each probe is compensated per channel per scope (probe compensated for CH1 needs to be recompensated for CH4 etc.).

Maybe you can get better combination results having a lab compensate the scope front end and a probe for each channel at the same time...and the resulted difference probably won't matter. Except maybe superficially.

It is so easy to fall into the rabbit hole of trivial precision.  In many fields.  What is the point of measuring to .001 microns when the bearing tolerance is .001 mm?  (Other than possibly production quality/process control).

Regards,


Dewey

7

Buy/Sell/Wanted / Re: FS [NL/EU] — Tektronix MDO4054C 500MHz + 6GHz Spectrum Analyzer — DPO4BND/MDO4AF

« Last post by NE666 on Today at 11:14:09 am »

Also why are we roasting sellers?

Quite. This seems to be increasing a 'thing' here.

If you want an item and you think the price is acceptable/negotiable then buy it. If it's not for you, then perhaps just pass on by? The poster of an *ad* is looking to make a sale, not solicit a review of their items nor their own reputation or sales technique.

Where there's no clear or obvious attempt at duplicity there's no need to turn every other member's classified ad into a two page Tripadvisor review.

8

Test Equipment / Re: Gigatronics 8652A power meter

« Last post by d-el on Today at 11:11:17 am »

Here is the ID of my device. It also shows 1.61 on the screen during startup.

Code: [Select]

GIGA-TRONICS, 8652A, 8651749, 1.61To dump V1.58, I first need to check whether my programmer supports the memory chip installed in the Giga-tronics.
The memory chips are in inconvenient packages, such as TSOP56.

9

Beginners / Re: Simpson 260- 270 On going efforts

« Last post by watchmaker on Today at 11:05:48 am »

Hi, can you please keep your posts about this meter in a single thread (I see that you already have two).

If you keep starting new threads on the same subject, people reading them lose the context of the previous ones. This will limit the quality of replies as people tend to be too busy to go back and search for them. They also get (rightly) irritated when they find that somebody else has posted the same information in one of the other threads.

Gyro,

This is one of the most nice, non aggressive reminder about double threads I have seen.

Regards,

Dewey

10

Test Equipment / Re: Program that can log/control many multimeters and other devices.

« Last post by HKJ on Today at 11:04:41 am »

So :color: is for buttons (exception is separator).

Documentation says:
:color: Color for an indicator, can be a name or (r,g,b) values. It Is is used on buttonson indicator, "Set" buttons and separator.

Why is there not a :fontcolor: option?

Java supports it: button.setForeground(Color.RED);

From start I wanted a simple to define style for the controls. For that reason I kept settings at a minimum.
Over time some more settings has been added and helped improve the look, usually they are optional, i.e. it is still possible to define they layout in a fairly simple way.

A tag to control font color would not change that, but I do not see much reason for it, most control do not really have a good way to use a fontcolor, info and infoAsk is about the only ones where it could be used.