Recent Posts

1

Other Equipment & Products / Re: Three most useful tools I got from AliExpress

« Last post by pope on Today at 09:50:04 am »

Yes, it is from "my orders" page.  Looky at the ratings as well as the number.  Came fast as well.

Regards,

Dewey

Thank you.

2

Microcontrollers / Dumped a 64mbit rom, any idea where to go from here?

« Last post by AJRube on Today at 09:45:31 am »

Hey folks.

A couple of years ago I made a silly mistake and purchased some mask roms not realising that they were not writable - definitely the sort of mistake you only make once. When the chips arrived, I stashed them away, purchased some proper Flash roms and called it a day.

More recently, I got curious about what was on them, so I dumped the contents with an Xgpro reader... I think successfully? But I'm not exactly sure.

The chips in question are Macronix 23C6410MC's - a 64mbit mask rom - in a SOP44 package - https://www.mxic.com.tw/Lists/Datasheet/Attachments/8177/MX23C6410,%205V,%2064Mb,%20v3.1.pdf

My assumption is that they are some sort of audio data, as they are stamped with Roland all over them, but I've tried various attempts at working out exactly what kind with no success (mostly trying out different encodings like FCE-DPCM or assuming they're PCM data, and running it through Audacity to see if I get anything resembling sound waveforms).

Does anyone have any ideas on how to get an idea of what the contents of the rom actually is?

I've attached a picture the beginning of the hex dump for reference - I have pored through the full 8mb worth of data for anything resembling even a hint and come up empty, no strings that look like anything vaguely user readable.

Thanks!

3

Other Equipment & Products / Re: Three most useful tools I got from AliExpress

« Last post by watchmaker on Today at 09:45:14 am »

Yes, it is from "my orders" page.  Looky at the ratings as well as the number.  Came fast as well.

Regards,

Dewey

4

RF, Microwave, Ham Radio / Re: Transistor tester

« Last post by madires on Today at 09:43:18 am »

I have some of those units, even a couple with genuine ATmega processor (AY-AT) and have never experienced a Ge trannie being identified as a JFET.

It's not a major issue and can happen when the BJT's leakage current exceeds some threshold. Or if a JFET has a very low I_DSS. If you don't use such transistors it's possible that you'll never encounter that issue.

5

Projects, Designs, and Technical Stuff / Re: a high side load switch made from n channel and p channel mosfet working princip

« Last post by BennoG on Today at 09:43:17 am »

This type of driver will only work up to about 20V, above that you need extra protection to not go above the maximum Vgs value.

Benno

6

Microcontrollers / Re: Looking for information on TEST pin and ways to DUMP mask ROM of PIC1650 PIC16xx

« Last post by jpanhalt on Today at 09:34:56 am »

Interesting read (link #1).  Link #2 might help.  I did not go through the whole thing.

https://www.eejournal.com/article/a-history-of-early-microcontrollers-part-9-the-general-instruments-pic1650/

http://bitsavers.org/components/gi/PIC/1983_PIC_Series_Microcomputer_Data_Manual.pdf

What tools to you have to read it?

EDIT: Its program ROM is only 512 12-bit words.  Do you know what the chip actually did?  If so, it might be faster and easier just to write a program to do the same on a more modern chip.

7

General Technical Chat / Re: What did you buy today? Post your latest purchase!

« Last post by tautech on Today at 09:34:38 am »

From RS
Small antistatic mat.
Antistatic gloves
25x 3W 3535 SMD LED's
HMC1118LP3D RF switches ..... any guesses what for ? 

8

EEVblog Specific / Re: EEVblog 1612 - Siglent SDS1000X HD 12 bit Oscilloscope Teardown

« Last post by shapirus on Today at 09:30:27 am »

While going frame by frame, you can see that the 2354 updates on each frame, while the 1024 usually displays a single waveform for 2 frames.

That's interesting. And we know that the SDS800X HD have crippled resolution of the displayed (but not captured/stored) waveform. I wonder if the 1000X HD does the same. And if the 800X HD has that frame rate reduction too.

That would mean they have some unfortunate bottleneck in the screen image rendering path.

9

Microcontrollers / Re: Looking for information on TEST pin and ways to DUMP mask ROM of PIC1650 PIC16xx

« Last post by woofy on Today at 09:23:21 am »

The only info on the test pin I have says "Test input not normally used".

10

Projects, Designs, and Technical Stuff / Re: role of optocoupler for biasing drain of amplifiers

« Last post by xvr on Today at 09:21:45 am »

> You said i should put a zenner diode .
did you meen in parralel to the power supply?

No. In series with R2 in my schematic

As for temperature raise, it calaculated as power, dissipated in MOSFET multiplayed by Temperature resistance (55W/C by your calculations). Power dissipation is I^2*Rdson

Graph in question shows changes of Temperature resistance via pulse characteristics.

Tja & Tjc are temperature resistancies from chip junction to ambient (this is case of bare chip in air) and for chip junction to case (this is variant of chip attached to ideal heatsink)
As you understand there is no such thing as ideal heatsink, so in later case you shoul add Temperature resistance of heatsink itself to Tjc to get real value