| promitheus |
I just finished my PCB for a relay volume control.
This is only the relay board which only has the relays, resistors and driver circuits.
The Ralays here are the Takamisawa Relays at 12 Volts. The resistors are Welwyn low noise but very good priced.
There is one more board with the PIC Microprocesor and encoder on it which looks like a small poti. I will be posting that soon. I donīt have the encoder yet.
What is very practical is that you can stack the relay pcbs to get as many channels as you want.
One board is for a stereo signal or one balanced signal. If you want to balanced signal like I will be using for the Balanced Line Stage then you can use 2 PCBs one on top of the other.
You can even use more pcbs for a surround volume.
More information will come soon. |
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| promitheus |
This the Relay board.
I tonly has the Relays, volume resistors and the driver parts.
This is the whole board. |
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| promitheus |
| This is a better pic, close up and sharper. |
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| promitheus |
| Some pics of the unfinished boards |
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| promitheus |
| These are the unfinished Control and PSU boards. |
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| sianturi |
| How 'bout the schematics? :) |
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| promitheus |
For the microprocesor control and info you can get from TIllīs website here:
http://home.tu-clausthal.de/~tpa/relais/index.html
Till was kind enough to give 2 PICs so I could start this project.
I really want to thank him for his help.
The relay part is a bit different from Tills or from Nelson Passīs.
It is a constant load attenuator. That means the load is always 5KOhms no matter what the setting.
I will find links and info on the subject.
Actualy you can find everything in this forum. |
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| till |
| Very pretty PCBs, i wish i had that pretty PCBs for my projects... Please report your findings with the corntroll, and keep in mind iīm still involved developing the firmware. Maybe you experience and ideas will help for further improvements on the code. |
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| promitheus |
Hi Till,
thanks for your nice words.
Without your help with the firmware my project would work in the first place. When I order some more boards I will give you some at cost price if you want.
Do you have done anything new with the firmware?
What I wanted to do is give the Volume control a display of some kind.
One idea is using 8 leds decoding the binary 8 bit code to decade.
Or a 7 segment led display.
Or the best but expensive a lcd display. |
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| till |
For the PCBs: Iīm interested.
The firmware is slowly but still in development. http://home.tu-clausthal.de/~tpa/relais/software.html
For display: i simply have 8 LEDs in parallel to the drivers at PortB, and i see the volume in binary. No problem. For a LCD (price starts at 7, i have some on hand) we would need more free pins, such a larger PIC. Else no problem. But i donīt know if its a good idea to have a LCD in the audio device - not really puristic and more RF noise. The pic with internal oscillator and such is choosen to have not to much noise in a minimalstic device. Of corse it would be possible to couple the PIC with a second one, controlling a display and remote reciver. I allready made a PGA2310 volume controll with LCD. |
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| promitheus |
Yeah I have heard that LCDs have a lot of RF noise going out.
I like the idea of 8 leads around the volume knob. Not in Binary though, you and I could understand it but not everybody does lol :-)
I thought of making a pcb for the frontplate with 8 LEDS that take the 8-bit data and decode it into decade from 1 to 8. Actually to do that you need only the last 3 bits.
Another Idea I have heard but donīt really like is a bar of leds with 16 Leds using the last 4 bits. |
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| guido |
| quote: | Originally posted by till
For the PCBs: Iīm interested.
The pic with internal oscillator and such is choosen to have not to much noise in a minimalstic device. |
Can you stop the clock on the pic you use? If so, you can stop the pic clock and awake the pic when pressing a button or remote input with an interrupt. I did that in my preamp, works fine.
There is one catch, it needs some time to wake-up. So you cannot decode the (e.g.) RC5 frame that comes in, but you have to wait for the second one to come by.
Regards, |
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| promitheus |
I have a few new pics from the volume control. I just tested the boards and they are ok.
The first picture here is the control panel from the back side. You can see the MicroPIC here with the data and power connector. |
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| promitheus |
Here is one more picture of the Control Panel of the other side.
You can see the Rotary Encoder from ALPS in the middle. |
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| promitheus |
Here is the last photo for tonight.
The Control Panel connected with the relay board. |
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| akira |
Hallo,
Do you have the files for building the PCBs. I d like to give it a try ...
Thanks
Akira |
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| wijgers |
Hi Promtheus,
Is one board enough for a balanced volume control, Or Do you need two boards for a balanced volume control
And Do have the board files OR pdf files and schematics, Do you want to schare them or keep them for your self?
Nils |
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| till |
| This realys are 2*change types. You need two boards for a stereo balanced control. One board would only give one channel balanced or stereo non balanced. I use a balanced control as to see on my www. |
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| promitheus |
Thatīs correct. For balanced you need 2 boards.
Iīm am now making the 2 board so I can test them together.
The problem with posting the boards is that I canīt convert the pcb or gerber files into pdf or jpeg.
If anybody has an idea how I can do that please help.
Itīs not that I donīt want to post the pcb work. |
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| Rarkov |
| quote: | Originally posted by till
For a LCD (price starts at 7, i have some on hand) we would need more free pins, such a larger PIC. Else no problem |
On the JAL List, many have contructed 2-wire LCD interfaces. (I seem to recall a competition for a one wire interface too!) Email me if you would like details...
Well done guys...looks good...Unfortunatly I've already splashed out on the APOX stuff!
Gaz |
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| promitheus |
| Well the Apox kits are very cool. |
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| sianturi |
| quote: | Originally posted by promitheus
The problem with posting the boards is that I canīt convert the pcb or gerber files into pdf or jpeg.
If anybody has an idea how I can do that please help.
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Promitheus,
U can use Neevia docuPrinter pro (trial version) at:
http://www.neevia.com/prodDP.htm#docuPrinter
I use protel dxp, and when I want to convert the PCB to PDF, I just print to the layout like printing the normal way, but the printer I used is DocuPrinter (after installing the docuPrinter).
Ciao! |
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| promitheus |
Thanks for the tip !
I will try it out. |
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| jwb |
| Very nice work. If you want, just zip the gerber files and post them. |
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| zygibajt |
Nice work Promiteus.
Till
I've seen your website with the information about relay attenuators.
Did you actually compared the relay attenuator with good (Elma for example) stepped attenuator ,series or ladder type.
I'm not that enthiusiastic about that constant load solution,becouse all of the relays are always in series with signal.That means 16 solder joints and 8 contacts in relays.
I have never bulit that kind of attenuator.I use stepped attenuators.
Looking in to service manuals of Aleph P (both of them) I can see how nice it is done.The drawback is that input impedance isn't steady,but in exchange we get 64 (Aleph P 1.0) and 256 (Aleph P 1.7) diffrent combinations.
I'm considering trying relay volume control.I'm wondering how does it compare sonicly to good ,ladder type stepped attenuator.
I even like the one from Aleph P 1.0 better.It is simplier solution,only 6 relays per channel.And what do I need 256 settings for? 64 is quite enough for me.
Did anyone compare relay type to stepped attenuators (true ladder type) sonicly?
Bartek |
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| till |
Rarkov, The LCD version will come in two versions, one with one PGA, one for multichannel or balanced stereo. It will use a 16F877, iīm working on the first test PCB right now. It will be possible to use with relays for volume control or PGAs in different firmware versions. The PCB at the pic attached was made by Pieter from Belgium, we collaborate on this project.
The apox is very nice, but much too expensive for me. Also i prefer to do it more diy.
zygibajt, i donīt have a stepped attenuator and the good quality ones are much more expensive than my solution. If i have taht much money for this hobby, i will spend it on some nice horn drivers or coax speakers before i buy expensive switches.
I built the aleph P 1.0 volume control before, and 64 steps are not enough for me. 255 are ok, if you want less its easy to modify the code to sort some out.
Also there is more than one way to use the relay attenuator.
I think about useing one for the D1 stage volume control in a DIY DAC with AD1865NK. |
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| promitheus |
So I made some pdfs. They should be in original size.
I zipped all of them in one file.
Itīs the pcb from the components side with the overlays and parts list.
Info on programmimg the PIC you can find on Tillīs website here:
http://home.tu-clausthal.de/~tpa/relais/index.html
Please note I am using another resistor system as Till is. Donīt mix the 2 up. Everything works the same but the attenuator is totaly different. |
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| sianturi |
Hello promitheus & till,
Looking at the schematics for the microprocessor part, I think we can use just 1 rotary encoder for 2 balanced channel (L + R balanced, that is for 2 relay boards, we use only 1 rotary encoder connected in parallel). Is that right?
Promitheus, could you kindly made the pdf file again? I think you missed to print the holes. There's no holes in your pdf files. Btw, very nice boards!
Thanks, |
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| promitheus |
Normaly the holes donīt show up when you print the pcbs.
What do you need the holes anyway? They will be drilled. |
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| promitheus |
You can use as many relay boards as you want with the same data bus.
You can use 3 relay boards for a surround system with a 6 channel volume control.
You can calculate any Load resistor value you want. for instance a 6 X 47Kohm volume control.
I will be using 2 boards for balanced volume control.
a 4 x 5 Kohm volume control. |
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| till |
| quote: | Hello promitheus & till,
Looking at the schematics for the microprocessor part, I think we can use just 1 rotary encoder for 2 balanced channel (L + R balanced, that is for 2 relay boards, we use only 1 rotary encoder connected in parallel). Is that right?
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As Promitheus sayed, the digital part with the PIC is able to drive a serios amount of driver transistors. So you simply hook up as many relay boards in parallel to the PIC as you need. The rotary encoder also could make use of a pushbutton function, if you want for mute, or for a change between 2 sources.
The 16F877 controller with LCD i work on will be able to read 2 encoders for more funktions. |
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| batee |
By extra functions, are you thinking of adding input selection? I've been thinking about how this could be implemented with only one pushbutton rotary encoder and a basic stamp, similar to what you're doing. A backlit LCD display would indicate the mode or function value (source, vol level, etc). Maybe a clock that just flashes 12:00...:)
Turn knob, change volume. Push button, select function by turning knob, push button to choose function (input source, etc), turn knob to change value of function. No user input for xx seconds, back to volume fumction. Push and hold button for x seconds = mute. Turn knob or push button again to unmute.
Should make a nice clean looking front panel. Any other functions we could add through this sort of interface? |
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| till |
| quote: | | By extra functions, are you thinking of adding input selection? |
I use the minimal relay version with 16F628 in my BZLS with 2 sources input selector on pushbutton. The board here http://www.diyaudio.com/forums/show...0807#post360807
allready has a connector for 5 sources selector.
| quote: | | Any other functions we could add through this sort of interface? |
I think about (does not mean all will be implemented soon):
- IR reciver for RC5 code
- support for multichannel PGA control
- support for relay control
- balance funcion ( set left and right channel independent)
- Allready implemented in the minimal version: store volume settings for sources individually, so you can A/B sources with different output levels at same volume level
- simple DSA interface for sending controls to Philips CD transport. This would be usefull for a CD PRO or CDM
based CDP with DAC, the controller tells the transport the Dac mode to use, and volume is set in the D1 I/V stage.
- Trigger outputs to switch on a power amp from the preamps control.
All would be usable with only one rotary, but it may be better to use two: sometimes you want to mute or change volume very fast. So for a multi function device it may be a solution to do mute and volume with one encoder, and all other function with a menue at the other. I just ordered a stock of alps-encoders for a good price. |
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| JC Fardo |
Promitheus
1) Could you please inform Takamisawa relay reference. I think Iīll only find Omron, Tyco or Fujitsu similares around here.
2) Is input load of your power amp 5Kohm?
3) Congratulations and thanks a lot sharing your project:)
JC |
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| promitheus |
On the board you can also use the Omron relays DPCO-G6A-234P at 12 volts, you can use the small Finder double relays.
I use the relays that Till uses. They are very good at that price.
The Balanced Line Stage from Pass DIY needs 5Kohm poti at the output for minimum distortion. An amp has 50Kohm input resistance. |
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| promitheus |
Just remembered.
You can check the pin configuration from the file Till has in the previous post. In the pdf file you can see what the pin layout is like. You can use any relays with this layout. |
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| JC Fardo |
Just a litlle clarification here:
| quote: | | The Balanced Line Stage from Pass DIY needs 5Kohm poti at the output for minimum distortion. An amp has 50Kohm input resistance. |
And on X-Pro post
http://www.diyaudio.com/forums/show...1198&highlight=
he says that the load impedance ( or the power amp ) must have the same pot resistance value. Sorry, Iīm new to this Volume Control matter. :(
Thanks again and Till for relay info and his previous write up
JC |
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| promitheus |
| It all depends where you use the volume control. This volume control at 5Kohm was calculated for the balanced Line Stage. Because the Amplifier input has a resistance of normaly 47KOhm it wonīt effect this volume control. |
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| nar |
Hi Promitheus I am very interested about your project - I like the idea of an ALPS encoder !!! Keep us informed please how things get :)
Best regards
Anael |
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| akira |
Hi promitheus,
Did you buy the rotary encoder in Germany ? I can t find it (nothing at reichelt, nothing at Farnell).
Akira |
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| akira |
Actually Radiospares in France doesn t have the one that is used by promitheus. But radiospares in germany (rscomponents) they have it.
Still if somebody (Promitheus) knows another supplier in Germany (cause I think you have to buy at leat 50 euros stuff by radiospares). |
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| nar |
Akira ,
I checked online and they don't have it . Only substitute they could propose would be STEC11B04 , but would it work?
We could do a grup buy for that one , at least 2 persons seem interested ...
I would be also interested about having 2 or 3 PIC preprogrammed , and same number of encoders .And you ?
Would go up the 50 eur barr to make command at rscomponents!!!
Waiting for replies , ;)
Best regards
Anael |
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| till |
| I have a stock of Pics, can programm them, and alps mechanical rotay encoders i have also enough. |
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| nar |
Super !!! Great news ;)
Please contact me by regular e-mail to discuss about financial aspects for encoders and prog PIC ;)
best regards
Anael |
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| promitheus |
Hi,
the encoder I used is the ALPS STEC16B vertical type order number : 265-1723 costs 2,74 |
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| nar |
Which company supplied it to u ? Searched rs and radiospares but the item does not exist...:confused:
Regards
Anael |
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| nar |
I tried to make online order at www.rscomponents.de
That didn't work :cannotbe: problem with the card , and I can't get the encoders in france :smash:
Could someone sell me some ? I need 2 , and 2 pics :)
Best regards
Anael
PS I make my own XLO like modulation cables. They sound very good ! Anyone interested contact me ;) |
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| till |
| no problem, contact me. |
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| Ruben |
Hi Till!
I like your idea very much! I have emailed you a funny story about swiss wines and attenuators...
Regards,
Ruben Begert. |
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| julius20 |
Hi,
is it possible to use this circuit in aleph P, only by changing the values???
greetings Arno |
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| julius20 |
... my question referred to promitheus`s relay circuit....
i hope you will excuse my bad english...!
Arno |
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| till |
feel free to write in german, or write a private message.
A volume control for balanced Zen line stage will be fine for aleph p, the amps are not very different. The resistor values for aleph p you can find in the service manuals. I use a control like the one i found in aleph p rev 1.7 for BZLS. My controller with 16F628 does not care how the relais are wired on the analog side.
Ruben, still waiting for some wine... |
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| Ruben |
Hi Till!
I'm quite buzy those times. I'didn't think about it since a long time, but I didn't forgot our "agrement" neither.
You can check the page http://www.dubois.ch/new/Vignerons.php and find my girlfriend on the picture (the third from the left). This is the web page of the family company.
By the way, Till, which kind of wines do you like much? I will try to send them from France, so I don't have to pay the border taxes, since Switzerland is not in european union.
Have a good day!
Ruben. |
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| till |
Ruben, iīm very happy everything is in order, take your time.
I fear i reach my language skill limitations at this point where i have to talk wine:
I like much Trocken, mittelschwere bis schwerer Körperhafte Weine, voll, oder wie es die Experten benennen. Ich trinke Weine eher nicht zur Mahlzeit sondern pur mit lauter klassischer Musik, allenfalls etwas geröstetets Brot dazu...
But its your descision what to send, and i look forward for interesting new taste experiences.
At this place i can also anounce i have now about 40 alps rotary encoders with pushbotton in stock to help out those members who cant find them localy. |
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| Demir |
| Have you tried reed relays ? Do they offer any improvement ? |
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| JasonL |
| WHat about buying some mucury wetted relays ? THey are expencive but they work better i used to have a whole pile of them but i used them in some project's.. |
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