Recent Posts

1

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

« Last post by RoGeorge on Today at 09:53:39 am »

Might be MIDI soundfonts, as upgrades/addons for MIDI keyboards and/or sound cards.  If they are soundfonts, they are under copyright, so they might be expensive enough to worth selling them.

2

Beginners / Re: The old "Replace blue LEDs with red LEDs" 7 segment question (74HC595)

« Last post by trondl on Today at 09:53:33 am »

It seems like dropping the supply to 3.3Vcc takes me exactly down to the ~5mA the blue LEDs operate under (Vf = 2.1).
Uncertain if the red LEDs are as bright though under those conditions.

I now consider this to be the most likely solution, as there is a 3.3V "supply" available on the PCB for the IR receiver.
Will need to investigate if it is powerful enough though, as I guess at least having 6-700mA available is a minimum for all the LEDs and logic (56 segments * 0.005mA = 280mA + logic and headroom).
There is also another 8 regular LEDs + 595 that handle the dBFS readings that still need their 5V.

I have some doubts though, as I can see on the layout that it appears that the IR supply is just a 3V3 Zener diode dropping the 5V line.
How much current can a small SMD Zener usually handle?
>1A?

3

Projects, Designs, and Technical Stuff / Re: TekBox TEM cell – how is it constructed ?

« Last post by tomud on Today at 09:53:17 am »

Well, we're slowly starting to start building the TEM cell. Let's see what the results of the test version will be... 

4

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.

5

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!

6

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

7

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.

8

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

9

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.

10

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 ?