DIY 40 step attenuator, anyone interested in such???

[BrianGT]

Thanks Brian.

They unfortunately dont have anything but grade 2 wire, I need grade 5 (Al6V4), and the sheets are too thick as well.

I need 1mm wire or 0.3-0.5mm sheet.

Any other ideas, Im really in a tight spot ??

Cheers

Magura

They have 0.016" sheets of grade 5, which google tells me is 0.4064 millimeters

--
Brian

 

[Magura]

They have 0.016" sheets of grade 5, which google tells me is 0.4064 millimeters

--
Brian

My calculator (and lately my brain as well) agrees with you...dunno why, but everytime I get in touch with imperial units things tend to go south

6*6*0.016 is not a bad option. I honestly would prefer wire though (just to be a pain now that I can get sheet)

Peter: The material is needed for the arm thats to connect the slider with the axle and work as a spring (rotary switch...im sure youve taken such apart at some point).

Magura

 

[Kravchenko_Audio]

Why titanium for the arm???

As one of those who can build a rotary switch ahem ahem

Why do you need titanium for your contact spring?? Would'nt half hard brass with an isolated silver contact be up to the stress??

Mark

 

[Magura]

Brass, steel and the like goes tired over time. Another reason for using titanium is that the elaticity is much higher, so its somewhat easier to make a liniar action spring.

The mating contact materials should also be different, so for the contact I intend to use CuBe2.5 as its readily awailable and seems to suit the purpose. You must never make 2 pieces of the same material and hardness slide against eachother, it will make heavy wear and loads of abrasion and the like as a consequence of that.

Magura

 

[fdegrove]

Hi,

You must never make 2 pieces of the same material and hardness slide against eachother, it will make heavy wear and loads of abrasion and the like as a consequence of that.

Bi-metal contacts aren't exactly ideal either when there some voltage on them, remember?

Cheers,

 

[Magura]

Hi,



Bi-metal contacts aren't exactly ideal either when there some voltage on them, remember?

Cheers,

True, but of two evils, I prefer the galvanic issue over a guaranteed slow death. The only solution to this would be to use a piece of solid platinium....which is unfortuantely rather expensive unless you have something up your sleeve I have overlooked??

Magura

 

[Peter Daniel]

Reading Cello broshure it says that "the contacts are made of platinum/palladium, cut from strips of custom made alloy, formed in their own tooling".

 

[Magura]

Reading Cello broshure it says that "the contacts are made of platinum/palladium, cut from strips of custom made alloy, formed in their own tooling".

Where can I find Cello on the web? A search gave me a whole lot of links to music instruments

Cheers

Magura

 

[Peter Daniel]

Cello is probably out of business now. It was a company started by Mark Levinson. You might try to search under Cello Music System. Here's the pic of their attenuator.

 

[Peter Daniel]

And here's switch description

 

[Magura]

Thanks Peter.

This is pretty much what I intend to make, just with 40 positions, no indexing and the whole thing will be sealed.

When the whole thing is sealed, I dont see much reason for spending another 200USD for platinum for the contacts ??

Magura

 

[fdegrove]

Hi,

When the whole thing is sealed, I dont see much reason for spending another 200USD for platinum for the contacts ??

Errrr...How much is it you think this whole thing is going to cost on materials and manhours again?
Price for a mono unit is O.K, $ or Euros too...
You can even use my one of my tooth fillings if it reduces cost...

Cheers,

 

[Magura]

Hi,



Errrr...How much is it you think this whole thing is going to cost on materials and manhours again?
Price for a mono unit is O.K, $ or Euros too...
You can even use my one of my tooth fillings if it reduces cost...

Cheers,

The total price of a stereo switch would end up between 1000 and 1500 USD if Id just go out and have it all made and paid by the hour. So you see, its not likely to be a mega seller

The material cost is a fraction of that...I know, but considering this switch would have material cost like 200USD for a stereo, adding another 200USD for something thats not going to make any difference....seems like a lot of money then

Did I understand your question right?

Magura

 

[fdegrove]

Hi,

Did I understand your question right?

I'd like to think so...but:

adding another 200USD for something thats not going to make any difference....

What's not going to make any difference? The platinum?
Dunno about you but I'd rather use coinsilver than platinum at that price.
$200,00 in production costs is a truckload % wise IMHO.

Lotsa peanuts indeed.

Cheers,

\using Hg wetted reed relays ages ago already...

 

[agent.5]

AT this price point, may I suggest pure silver for contact?

 

[Magura]

What's not going to make any difference? The platinum?
Dunno about you but I'd rather use coinsilver than platinum at that price.
$200,00 in production costs is a truckload % wise IMHO.

Lotsa peanuts indeed.

Cheers,

\using Hg wetted reed relays ages ago already...

Oups..I realize Im talking in riddles...yes I meant the platinum.

200USD is a whole lot of bottle collecting in the local park

Magura

 

[Magura]

AT this price point, may I suggest pure silver for contact?

Thats whats going to be used. CuBe2.5 for the slider.

Magura

 

[fdegrove]

Hi,

AT this price point, may I suggest pure silver for contact?

Unfortunately pure silver is rather too soft to be much use here.

Cheers,

 

[Magura]

Hi,



Unfortunately pure silver is rather too soft to be much use here.

Cheers,

If the surface of the contacts is big enough it should work fine. It must though be mated with CuBe2.5 to avoid wear.

EDIT: Well not pure silver but what they call fine silver, its got some copper content, about 7.5%.

Magura

 

[Brian Donaldson]

Bump


How's the progress?