Recent Posts

1

Microcontrollers / Re: STM 32F4: any way to make it self program its FLASH from an external SPI FLASH?

« Last post by nctnico on Today at 04:05:31 pm »

EMI coupling inside the chip

No. Read again. It would be very hard to get EMI inside a chip.

But not impossible. At some point I designed a 1000W DC-DC converter and put a temperature sensor chip next to the switching transistors. With the converter on, the temperature measurement where allover the place. At first I expected the SPI bus but that was working just fine (I routed these on an inner layer as a precaution). The chip itself just stopped working (Microchip, no surprise).

2

Test Equipment / Re: Magnova oscilloscope

« Last post by woody on Today at 04:05:19 pm »

One last observation: after being switched on for 3 hours the device does run a bit hot; (IR measured) temp of the heatsink on the back is around 50 deg C, the little plate above that (where the SG will be put behind) around 47. Ambient is 22 deg C. The scope's fan is still off though, for which I am very grateful 

3

Microcontrollers / Re: Can your program, ever damage an MCU ??

« Last post by eutectique on Today at 04:03:10 pm »

On NXP S32K, you can overstress and eventually damage flash if you write ones to already written location(s) -- that's what RefMan says.

Or think of an MCU powered by a PMIC, usually accessed via I2C. You can set a very wrong voltage or sequence which could cause physical damage. Not MCU feature, strictly speaking, but still falls under definition of "your program".

4

Test Equipment / Re: Rigol DHO800/900 new firmware... 1.03

« Last post by ptluis on Today at 04:02:42 pm »

What firmware version "bricked" your scope? v00.01.03.00.04 or v00.01.03.00.06?
I'm still able to download v00.01.03.00.06 from supportint.rigol.com

hey my friend don't do it, with any damn version, wait for Rigol to provide a new version with clarifications

Don't worry mine is still waiting in the shopping cart   

5

Test Equipment / Re: Siglent SDS804/814X HD or Rigol HDO914S for Mechatronics student

« Last post by Jack359 on Today at 04:00:39 pm »

Yes, it became clear to me. Thanks.

If I ground the scope and poke high voltage stuff with it, I can destroy the scope.
If I don't ground it, I can kill myself cause then the BNC connectors and perhaps the case become live. There are electrically insulating gloves but they are not comfortable or very cheap.
The only safe way to do it is with differential probes.

6

Beginners / Re: How to properly compensate a composite OP that aims for high open loop gain?

« Last post by magic on Today at 03:56:55 pm »

No, I showed how to shoot yourself in the foot

Problem is that the midpoint between U1 and U2 is effectively a virtual ground, so R2+C1 load the feedback resistor R1, resulting in more than unity closed loop gain at high frequencies where C1 impedance is comparatively low. That's not exactly a voltage follower anymore.

It can be fixed by "bootstrapping" the midpoint, by connecting U2 IN- to the input signal, but then U1 has to produce the same swing as U2 and requires the same error voltage at its inputs, hence open loop gain is no longer improved over the baseline single opamp case. But this scheme still appears to improve correction of U2 output stage errors, so perhaps it could have some value for audio and such.

This is all because I tried to be clever and use feedback to control U1's contribution to overall loop gain. People actually build high-gain composites, but they usually use passive RC networks between the opamps to shape frequency response. Maybe for good reason. Look up Samuel Groner's "Low-Distortion, Low-Noise Composite Operational Amplifier" for an example of that.

7

Test Equipment / Re: FNIRSI-1013D "100MHz" tablet oscilloscope

« Last post by Atlan on Today at 03:55:49 pm »

The indicator is mainly there for this gadget.


Because the original fnirsi firmware is severely limited.

The ACQ menu allows you to change the sampling frequency, thus displaying a larger part of the progress of, for example, an I2C signal.
The oscilloscope has a memory of 3000 samples in the FPGA. This indicator shows where you are in the sample memory. (I would like to complete it - it does not allow movement by dragging the finger in the lower part and does not match the size)

And I still failed to implement long memory - to use 3000 samples, although the stupid FPGA design can only use 1500, ie from the center where the trigger is.

8

Test Equipment / Re: Magnova oscilloscope

« Last post by woody on Today at 03:54:38 pm »

Hello,

will the resolution really be higher?

Best regards
egonotto

No. According to my display: 1920x1080 / 60Hz / 24bit color.
But I established the DP output works 

9

Repair / Re: Anyone have National Semiconductor "HPC" User's Manual?

« Last post by Conventional Wisdom on Today at 03:54:15 pm »

Bump.  Still interested.  Thanks!

10

Test Equipment / Re: Magnova oscilloscope

« Last post by core on Today at 03:54:14 pm »

Can the right columns be hidden to use more space for the signal?

Yeah, things are getting a bit crammed on that little screen.

It's not about size. It's about pixels.

At first glance the columns on the right take up say 180 pixels. That leaves 900 for signal.
So it approaches the DHO1000, which has 800 pixels horizontally.

If the full width can be used for signal, it will make a significant difference.

Now I hope the point of the question is understood.

Later edit : nope, it takes from 1920, not from 1080. So It's OK