ST35 Rev.D finished in Europe

[Guest]

Hi,

first of all a happy new year to all, even if the old ended that badly for so many people in Asia. My best wishes are with them.

Here are the first photos of my recently finished ST35, Rev.D. There is nothing special except that it can be controlled with a remote control (switch on / off and volume setting) and the bias currents are displayed as small bargraphs beneath those sweet little tube symbols on the display.
The volume setting is done with a relay attenuator, that is also controlled with the microcontroller.

If you have questions, ask :-)




Jochen

[JochenH]

Damn, this login feature doesn't work for me. That was my post.

Jochen

[Guest]

NICE WORK.


Question: how did you hook up the LCD screen, and is it actually taking readings on the tubes? Any info about the remote control?

More pics would be nice too.

[JochenH]

Hi,

i used an Atmel ATMega8 microcontroller to control the VFD display, the relay attenuator, the power relays and the IR receiver.

The VFD is a 140x16 dots display which is connected in parallel mode.

I pick up the voltages from the testpoints, which are about 350 mV in respect to GND and convert them with the internal 10bit ADU of the microcontroller and finally display these bargraphs.

The software can decode RC5 remote commands, currently "Power ON/Off", "Mute", "Vol-" and "Vol+" are implemented. Due to size constrains the volume can only be set for both channels the same (no balance)

Here is a detailed picture of the diplay content, unfortunately my camera is really bad.



More pictures coming soon.

Jochen

[Guest]

I take it you wrote all the software yourself for the microcontroller? Is there a compiler one can use, and if so, what language? Assembler or some higher language?

[JochenH]

Yes, i wrote the complete software for the microcontroller myself, this is my profession so not the problem.
I used the freely available WinAVR (AVR GCC) package from http://www.avrfreaks.net to write the software in 'C' and then used the Atmel starterkit STK500 to program the software into the microcontroller. The binary is about 7.5 KB because all the softfonts i used for the display take a lot of space in flash memory.

Jochen

[Shannon Parks]

Yes, i wrote the complete software for the microcontroller myself, this is my profession so not the problem.
I used the freely available WinAVR (AVR GCC) package from http://www.avrfreaks.net to write the software in 'C' and then used the Atmel starterkit STK500 to program the software into the microcontroller. The binary is about 7.5 KB because all the softfonts i used for the display take a lot of space in flash memory.

Jochen

Hi Jochen,

Excellent work, Jochen! My workplace is fairly Atmel centered these days (PICs and Motorolas are in our legacy products). We like the ATMega16 and ATMega128 a lot - all coded assembly. I just hate it when I forget to set the fuses properly.

Would you open source your code? You could stipulate 'free hobbyist use only'. I'd send you a couple more ST35 boards or and Ike set if you were interested. I'd host any files.

Pictures of the innards would be sweet.

Shannon

[JochenH]

Hi Shannon,

glad you like it. Yes, I would make the source code along with the schematics of the control circuit public available.
I have to add some comments in English and i also will add a learning fuction for the remote control so one can use other IR senders than i do. I have done this in another project, so this is no problem. I hope i can finish this by next weekend. I will then also have more photos for you and other interested DIYers.

Jochen

[Guest]

awesome. :D


I might just have to order another st35 now.....darn.

[JochenH]

Hi all,

here are the links to the schematics and the PCB of the preamp in PDF format:

Schematics:
http://www.jhartnacke.de/media/pdf/st35/st35.sch.pdf

PCB:
http://www.jhartnacke.de/media/pdf/st35/st35.brd.pdf

The revision of the source code is not complete, i will try to finish this in the next days.

Productive comments are welcome :-)

Jochen

[JochenH]

OK, here are some photos from the inside. Hope you like it.











Jochen

[dhuebert]

I would appreciate a block diagram of the whole system and a brief circuit description. A kit would be great fun.

Don

[JochenH]

Hi,

OK, here is the link to the sorce code of this project.

http://www.jhartnacke.de/media/archives/st35/st35-intl.zip

If you program this into the controller, set the fuses for the internal RC oszillator with 8 MHz! Or change the source (rc5.c and st35.c) to use another frequency.
My time for commenting is limited at the moment, but if you have questions i try to answer them.

@Don:
Have you downloaded the schematics and want a block diagram for this or for the whole amp?
I cannot provide a kit i think because it doesn't make sense to send this standard PCB around the world, especially because of the current euro/dollar ratio. Good time for me to buy in USA :-)

Jochen

[JochenH]

Hi again,

here are the last bits and pieces for you.

Link to the Cadsoft Eagle schematics and board file (free version compatible):
http://www.jhartnacke.de/media/caddata/st35/st35.sch
http://www.jhartnacke.de/media/caddata/st35/st35.brd

You can download Eagle for free at http://www.cadsoft.de

And here is the windows simulator i wrote for developing the user interface. It is a Windows executable for you to have a preview on the display content of "the real thing":
http://www.jhartnacke.de/media/program/st35sim.exe

Have fun

Jochen

[Shannon Parks]

Hi again,

here are the last bits and pieces for you...

You went above and beyond, Jochen. Thanks a million!

Shannon