My new multichanel passive balanced pre-amp, battery/solar powerd, remotecontrol. - diyAudio
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Old 5th October 2003, 10:00 PM   #1
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Talking My new multichanel passive balanced pre-amp, battery/solar powerd, remotecontrol.

Almost done here, Gerbers should be going out tomorrow night. Canít wait!!!

Here are the architectural outlines, they will explain everything:

The attenuator module.
http://pages.infinit.net/helloftp/attenattenuator.png

The main processor & display / keypad PCB module.
http://pages.infinit.net/helloftp/attenprocessor.png

Here is the latest schematic of the attenuator. This should give you an idea of how the relay pot is wired.
http://pages.infinit.net/helloftp/attennewsmall.png
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Old 5th October 2003, 10:58 PM   #2
x-pro is offline x-pro  United Kingdom
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Hi Brian,

What is the attenuation range and steps on your design?

Regards

x-pro
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Old 5th October 2003, 11:04 PM   #3
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Listed in the first illustration in the top middle white box.

64 steps, 96Kohm, 48Kohm, 24Kohm, or 12Kohm, Constructed with 0.1%, or 0.5%(econo) resistors.

Current draw is listed in the bottom left hand corner box.

Module sizes are in the bottom right hand box.

If you are having problems seeing the fine text, it's Internet Explorer, you just need to un-zoom the image, or, download it & view with a picture viewer.

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HELP!!! I notice some over-sized image posts do not make
Internet explorer crunch up the image, how do I do that???
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Old 5th October 2003, 11:21 PM   #4
cowanrg is offline cowanrg  United States
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if the picture is shrunk to fit, hold the cursor over it, and you will see icons appear, in the bottom right, click that icon, will goto full size.
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Old 5th October 2003, 11:32 PM   #5
x-pro is offline x-pro  United Kingdom
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Hi again,

thanks for a quick reply, I didn' t read the text properly, sorry. There is stated clearly that the pots are linear. I did somewhat similar design couple of years ago, however I did use 7 relays per channel to give me 80 steps of 1 dB = 79 dB max attenuation + one more relay for a complete mute. My design had logarithmic curve for volume, otherwise it looks quite familiar .

Good luck!

x-pro
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Old 5th October 2003, 11:43 PM   #6
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Well, if you look at the software options on the processor page, I have a Volumetric, or Logarithmic software emulation.

However, that just makes a nicer volume curve with 24 steps, 24 sending the full 63 level on the relays. It does not simulate the surface resistance charactersist of a real logarithmic pot, or does it? Man, now my head is now spinning off in the wrong direction.
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Old 5th October 2003, 11:56 PM   #7
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Quote:
Originally posted by x-pro
Hi again,

I did somewhat similar design couple of years ago, however I did use 7 relays per channel to give me 80 steps of 1 dB = 79 dB max attenuation + one more relay for a complete mute. My design had logarithmic curve for volume, otherwise it looks quite familiar .

Good luck!

x-pro
Thanks!

You should see the new relays I'm using, Omron G6KU-2G. They latch & they are the puniest thing i've ever seen. They are 10mmX6.5mmX5.2mm that's SMALLER than a DIP8. I even broke 1 open to see the distance on the contact switches, they are so short and small, you almost need a magnafying glass to get a good look at the contacts.
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Old 6th October 2003, 12:04 AM   #8
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Here's a better view of the attenuator's schematic.

http://pages.infinit.net/helloftp/attennew.png
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Old 6th October 2003, 05:17 AM   #9
x-pro is offline x-pro  United Kingdom
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Hi Brian,

I did use exactly the same relays - G6K, thought not the latching type. These are not just small, they've got very good contacts quality as well and very low current consumption. Excellent choice . I did look at the larger schematics and have to say that the way you've organised the switching is quite different from what I did.

Cheers

x-pro
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Old 6th October 2003, 07:21 AM   #10
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[QUOTE]Originally posted by Brian Guralnick
[B]Here's a better view of the attenuator's schematic.

----------------------------------------------------------
Brian

Looks very good. Are you making pcbs and building plans available and at how much pl?

What are the attentuator steps and the reistors types used?

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