Recent Posts

1

Projects, Designs, and Technical Stuff / Re: Can't make sense of this circuit on a controller loop

« Last post by mikerj on Today at 08:36:47 pm »

a non inverting configuration with positive feedback U301A

The common source connected transistor Q300 inverts the signal being fed back to the non-inverting input so it's negative feedback, not positive.  This is an inverting amplifier with the gain set by R302/R303, in this case a gain of -1 which corrects the inverted output of the integrator.

2

Test Equipment / Re: DH-801 Electronic load

« Last post by tszaboo on Today at 08:31:35 pm »

Mine just arrived 

Did you manage to look inside it? I'm really wondering if it has more than a TO220 transistor dissipating the heat.

3

Repair / Re: Keysight 34450A Help

« Last post by Louis_C on Today at 08:30:29 pm »

I had the 34450A connected to our Fluke 5500A during the internal cal/adjustment procedure.

4

Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD

« Last post by 2N3055 on Today at 08:29:24 pm »

Tis in the datasheets for the instrument it fits:

RTFM / RTFDS?? We have to read to get info now?? 

I would curse more quietly in your place, since you apparently did not read hpw's question. 

My suggestion to you is to browse quickly through his posts to get a feeling what kind of language is used in majority of them.
He fires off opinions on a whim, rarely verify information and is very rude and dismissive in general.
Fact that he is right sometimes does not buy him goodwill, based on attitude alone. He burned that bridge...

Sure, however he is a Siglent owner and user therefore any feedback need be received and considered despite it is sometimes confusing to decypher.
For those that use English as their 2nd language this always a challenge.

Yes Rob,

And as you know, on many occasions I to tried to explain something when I felt I could provide some information. But on many occasions he does exactly what he did here: he doesn't ask for help but just shoots of a bunch of insults and drops the mike.
In which case I can chose to reply with some comeback (which ends up being negative experience, because he never gets the message of needed change, and I get pushback from others for "patronizing" him or whatever else) or I can simply ignore it because he didn't really ask for any response. And I leave to the rest to figure out on their own what is going on.

We can do only as much.

5

Microcontrollers / Re: Powering an STM32F103C8T6 With 12 Volts?

« Last post by radiolistener on Today at 08:28:18 pm »

My point is that because modern Blue Pill boards seem to be made only with counterfeit chips, they don’t behave consistently.  It doesn’t matter that the F103 is (or was) common: the Blue Pills you can buy today don’t contain a real F103. A beginner is unlikely to be able to identify and compensate for this, so it’s better to go for a board that uses an MCU that has yet to be counterfeited, for example ESP32 or Rpi Pico.

I bought a couple of Blue Pill boards on aliexpress about 5-6 years ago, they had 128 kB FLASH instead of 64 kB and working pretty good. It is enough for my needs. I cannot say something about modern fake chips, but I hear that modern Blue Pill boards from WeAct also works good.

PS: If someone interested, I can prepare and share simple project for Black Pill STM32G431CBU6 for GCC compiler. It seems that there is not so much examples for this nice board, but it is very interesting because this is Cortex-M4 which can run at 170 MHz with 213 DMIPS and with 0-wait-state execution from flash. Also it has 128k FLASH, 32k RAM, hardware FPU, hardware CORDIC and FMAC accelerators and also has 12-bit DAC in addition to 12-bit ADC. Pretty nice board for DSP experiments. 

6

Beginners / Re: Lab PSU for learners

« Last post by JustMeHere on Today at 08:27:48 pm »

If you want linear:

https://www.amazon.com/Tekpower-TP3005P-Programmable-Variable-Regulated/dp/B06XCQN82X

If you don't care about switching power supplies than go with any of these:

https://rdtech.aliexpress.com/store/1100599049

7

Projects, Designs, and Technical Stuff / Re: Homebrew Lock-In Amplifier

« Last post by Kleinstein on Today at 08:26:15 pm »

The new data look a lot less noisy. Especially the consecutive readings are relatively similar. There is a chance to have some thermal variations if the actual signal or amplifier gain.

8

Test Equipment / Re: Enabling options on Agilent ESA series E4402B E4404B E4405B E4407B

« Last post by PA0PBZ on Today at 08:21:25 pm »

by the way may i ask how to add an option to the ESA-L1500A series without an ID number compared to the first level of 4411?

I have no idea, the option keys I can generate are based on the HOSTID so if you don't have that I'm afraid I can't help.

9

Test Equipment / Re: Siglent SDS3000X HD and upgraded SDS1000X HD

« Last post by 2N3055 on Today at 08:21:24 pm »

My suggestion to you is to browse quickly through his posts to get a feeling what kind of language is used in majority of them.
He fires off opinions on a whim, rarely verify information and is very rude and dismissive in general.
Fact that he is right sometimes does not buy him goodwill, based on attitude alone. He burned that bridge...

I do not like hpw's style either. But if we want to focus on facts for a moment, hpw had voiced specific concerns about clock jitter and phase noise (in the context of future scopes with very high acquisition rates). So tautech's datasheet reference was missing the mark, and so was Josh's usual "Someone caught a blow, let me give them another kick in the teeth" response.

Thank you for explanation.
Now let me explain better what I said.

Really, go and read. He didn't "express concern" he has been doing this snarky, rude, derogatory comments for a long time.
He is always like that. He keeps repeating this even for low end scopes. Never he explained what kind of earth shattering cutting edge science he does that requires that kind of specifications...

10

Repair / Re: IWATSU oscilloscope Cal signal square wave showing as ramped / curved signal

« Last post by Michelle on Today at 08:20:29 pm »

I did try ch2 with the same result

That's interesting.  The input circuitry, including the circuitry and attenuator switches actuated by those V/Div knobs, are not shared between channels.  Seeing the problem on both channels more or less rules out a lot of things.

Not necessarily.  Both switches have been in the same environment.  If they've been sitting around unused for years, it wouldn't surprise me to find that both of them are similarly oxidized.  Actually, just spinning the switches back and forth a few times might be all that's required to cut through the oxide layer.

Michelle, another reason to always start with the basics is that lots of beginners read these messages.  When I answer a question I often 'play to the audience' rather than just the OP.  Besides, although I'm an electrical engineer, I don't know shit about automation engineering so if you ever answer a question from me I hope you'll use words of one syllable or less!  We're all beginners!   

Ed

You’re right it probably makes just as much sense to assume someone didn’t do something basic as it does to assume they did. Either way I realize I need to provide more information at least on a forum like this where people can actually understand what you’re saying.

Sorry for having an attitude earlier I needed to eat lunch lol.