DIY ribbon mic w/ Mylar as a ribbon material?

[cyrano]

A company in Japan made optical mics a few decades ago. The Japanese radio (education dept) had these on test for years. Expensive stuff. No problems with electrical/magnetic noise. Very small pickup, optical fiber.

Afaict, these are still made for hostile industrial environments.

Now if I could only remember the companies name...

While looking for that company, I came across a 1999 press release from Kenwood. Apparently, they were looking at optical mics too:

https://www.kenwood.com/jp/en/news/microphone.html

One of the leading companies was Phone-Or Ltd. Israeli defense industry.

I think the Japanese company commercially evolved into this:

https://www.optoacoustics.com/industrial/optical-microphones?gad_source=1

 

[sr1200]

No, metalized mylar does not work as ribbon material: too high self-resistance... pure aluminium for a 5 cm long and 1-2 micrometer thick ribbon tipically used in mikes has 0.01 to 0.1 ohm self-resistance, permitting the few microampere current developed by it to circulate in the step-up transformer primary winding.

I guess what im not understanding is if its got, say gold sputter on there, why is the mylar even in the conversation at that point, isn't the signal going to pass through the gold (lower resistance) over the mylar? Wouldnt the mylar just be the carrier of the conductive material at that point?

 

[gyraf]

I guess what im not understanding is if its got, say gold sputter on there, why is the mylar even in the conversation at that point, isn't the signal going to pass through the gold (lower resistance) over the mylar? Wouldnt the mylar just be the carrier of the conductive material at that point?

yes, but as I mention earlier, there's too little gold

 

[Biula]

I guess what im not understanding is if its got, say gold sputter on there, why is the mylar even in the conversation at that point, isn't the signal going to pass through the gold (lower resistance) over the mylar? Wouldnt the mylar just be the carrier of the conductive material at that point?

In a conductor what defines the specific resistance is its section area: 10 angstrom sputtered gold (say, 5 millimeters wide) ribbon has negligible cross section, a 1 micron x 5 millimeters aluminium one has 1000 times the area, hence much lower resistance.

 

[sr1200]

In a conductor what defines the specific resistance is its section area: 10 angstrom sputtered gold (say, 5 millimeters wide) ribbon has negligible cross section, a 1 micron x 5 millimeters aluminium one has 1000 times the area, hence much lower resistance.

Ahhh ok i think i get it now. So we're saying because the gold or aluminum or whatever is coated on the mylar, that surface area winds up having a higher resistance since the area is 'smaller' than something made entirely out of that material. I think.

Thats very interesting. I had bought a conductive ink set a while back with these pens that essentially draw a silver conductive line on paper or anything the ink will stick to. I've actually repaired some things around the house with that when a trace pulled up or something with varying degrees of success. I would think that that would have high resistance, but it doesn't. I assume the ink is a heckuva lot thicker than a sputtered surface though so that makes sense if i got the above correct.