Hello Patrick
I did test the old licron which was based on Tinoxide. I didn't test the new, crystal clear, one. According to the producer the crystal version is based on a 'propietary polymer'. Like other products there is little or no information about the product in regarding to the use in ESLs (I assume it wasn't designed for that so I can't blame them). So, just for example, to what degree this product resists ozone is unknown te me. This makes any comparison prior to use very difficult and you could consider just buying some licron and see how it holds on the long term.
The shelf-life of the EC/HTEC-coating-fluid itself is limited (that's why it has to be stored in the fridge) but once applied this is no issue. Sold it from 2003 to 2009 to DIY and based on the feedback from that period and afterwards I can say it is very stable.
I did test the old licron which was based on Tinoxide. I didn't test the new, crystal clear, one. According to the producer the crystal version is based on a 'propietary polymer'. Like other products there is little or no information about the product in regarding to the use in ESLs (I assume it wasn't designed for that so I can't blame them). So, just for example, to what degree this product resists ozone is unknown te me. This makes any comparison prior to use very difficult and you could consider just buying some licron and see how it holds on the long term.
The shelf-life of the EC/HTEC-coating-fluid itself is limited (that's why it has to be stored in the fridge) but once applied this is no issue. Sold it from 2003 to 2009 to DIY and based on the feedback from that period and afterwards I can say it is very stable.
At the moment I'm also trying to build some ESL-elements. I stumbled upon this thread, but it's a bit long to read everyting.
I'm using a can of kontaktchemie 100 antistatik : http://www.kontaktspray.hu/?download=A-100_TDS_EN.pdf
This works quite well for the moment. (I don't know how long it lasts)
I do have some problems with leaking of the charge. This shouldn't be related to the sort of coating, but it might... (more likely it's some glue used in the construction which is leaking)
Anybody else tried this already?
I'm using a can of kontaktchemie 100 antistatik : http://www.kontaktspray.hu/?download=A-100_TDS_EN.pdf
This works quite well for the moment. (I don't know how long it lasts)
I do have some problems with leaking of the charge. This shouldn't be related to the sort of coating, but it might... (more likely it's some glue used in the construction which is leaking)
Anybody else tried this already?
Humidity shouldn't be the problem. And I don't know what their definition of mechanical stress conditions is. There isn't that much stress on the membrane. It's mostly only forward and backward pushing, but not much stretching. (and stretching would be the largest problem I think...)
Hmm, It also says that after 83 days the resistance has risen from 2MOhm to 46MOhm. But that's still low enough
Hmm, It also says that after 83 days the resistance has risen from 2MOhm to 46MOhm. But that's still low enough
Hi,
Yes, if the HDPE package is properly closed that will be absolutely safe. However, care must be taken to avoid accidental ingestion by children.
The expiration-date is printed on the package and is valid under the mentioned storing conditions which is in the fridge.
A detailed instruction is available for users; it is brushed on the Mylar®.
Martin-Jan
Hello EUVL,
There was a technical article in the February 1956 issue of Wireless World on this topic.
They author claimed that distortion free operation for large diaphragm excursions could only be obtained if the two sides of the diaphragm were charged and insulated from each other by feeding the HV thru independent high resistances.
In the Letters to the Editor in the March 1956 issue, Peter Walker explained that if the capacitance through the diaphragm, from one coating to the other, is large compared to the capacitance between the coatings and adjacent stators then the operating conditions approached those of a single coating on one side of the diaphragm fed through a high resistance. Another letter provides the equations showing why separation of charges on either side of the diaphragm has no advantage over a single conductive side with the same net charge.
As MJ Dijkstra already mentioned, minimizing the mass added to the diaphragm is a very good reason to stick with one sided coatings.
If anybody is interested, I could see about getting an electronic copy posted if the copyright has expired.
Measuring coating resistance
I am measuring comparatively Acoustat coating and my own formulation. I notice many of you cite surface resistances in the Megaohms. For example with my multimeter probes I get around 340 KΩ with the probes 1 inch apart on the Acoustat coating and on my formulation at the same distance apart the meter reads 38 MΩ. The farther apart the probes are the more resistance I read. I know this might sound a bit plebeian, but when numbers are cited by those measuring coating resistance is there some particular length of coating that is being measured?
I am measuring comparatively Acoustat coating and my own formulation. I notice many of you cite surface resistances in the Megaohms. For example with my multimeter probes I get around 340 KΩ with the probes 1 inch apart on the Acoustat coating and on my formulation at the same distance apart the meter reads 38 MΩ. The farther apart the probes are the more resistance I read. I know this might sound a bit plebeian, but when numbers are cited by those measuring coating resistance is there some particular length of coating that is being measured?
Hi,
@zweetvoetje. The Diaphragm finds itself under a constant mechanical stress, added the movement when a music signal is applied. It doesn´t matter how the diaphragm moves, because every movement means a mechanical stress. I doubt that the coating could proove to be longtime stable. A resistance of 46Mohm is a rather low value of surface resistance.
@Bolsert. a elec copy would be appreciated
jauu
Calvin
@zweetvoetje. The Diaphragm finds itself under a constant mechanical stress, added the movement when a music signal is applied. It doesn´t matter how the diaphragm moves, because every movement means a mechanical stress. I doubt that the coating could proove to be longtime stable. A resistance of 46Mohm is a rather low value of surface resistance.
@Bolsert. a elec copy would be appreciated
jauu
Calvin
@speedracer, if you coat a rectangular piece of diaphragm, the resistance shouldn't vary on size.
I do have some final ESL's, from ~10years old, and they have coating on both sides, with (i think, didn't measure) opposite voltages accros.
To me this just seems like extra weight.
However, high-coating resistance definitely has advantages, that's important for low frequencies.
I do have some final ESL's, from ~10years old, and they have coating on both sides, with (i think, didn't measure) opposite voltages accros.
To me this just seems like extra weight.
However, high-coating resistance definitely has advantages, that's important for low frequencies.
Sheet resistivity is normally expressed as ohms/square.
The resistance of a square conductive sheet is the same no matter what size it is so long as it remains a square.
Two point probe measurements of sheet resistivity is problematic due to contact resistance.
Here is a post outlining a method I described last year using foil tape to avoid contact resistance issues:
http://www.diyaudio.com/forums/planars-exotics/109789-esl-diaphragm-coating-17.html#post1897769
Pictures of a two point probe with some discussion:
http://www.diyaudio.com/forums/plan...-do-you-measure-your-coating.html#post2142968
Calvin's post from earlier this year describing measurement technique:
http://www.diyaudio.com/forums/planars-exotics/93444-conductive-coatings-4.html#post2107923
More discussion of measurements techniques including the use of non-square measurement probes to provide amplification of the resistance measurement:
http://www.diyaudio.com/forums/plan...rface-resistance-measurement.html#post1346091
And more:
http://www.diyaudio.com/forums/planars-exotics/93444-conductive-coatings-2.html#post1101259
you get the idea....search utility is your friend
Attachments
As others mentioned it would be reasonable to contact manufacturers of PET capacitors
or even plants directly. Normally they do not mind selling a small batch of the film, usually leftovers.
RC hobby shops are O'K as well, also the pricing is outrageous.
Al is easily removed by sodium carbonate or very diluted sodium/potassium hydroxide.
Basics also promote adhesion for your coating.
Do not use strong solutions - they'll destroy thin film in no time.
Hi,
I recently run into this problem. I've been using PVA glue, water, and black ink as my coating formula. It has been working well for me. But, it's now rainy season and it has been raining and raining everyday. The humidity is extremely high. I start to notice the charge indicator (little neon bulb) that use to blink only 2 -3 times per minute now blinks more than one time per second. And I also notice the distortion in sound once in a while. Do you think that this phenomena is related to diaphragm coating? If so, can anybody suggest me a better coating material?
Wachara C.
I recently run into this problem. I've been using PVA glue, water, and black ink as my coating formula. It has been working well for me. But, it's now rainy season and it has been raining and raining everyday. The humidity is extremely high. I start to notice the charge indicator (little neon bulb) that use to blink only 2 -3 times per minute now blinks more than one time per second. And I also notice the distortion in sound once in a while. Do you think that this phenomena is related to diaphragm coating? If so, can anybody suggest me a better coating material?
Wachara C.
Assuming your coating is able to charge the Mylar film fully at both low and high humidity conditions, I can only adress the higher blinking rate to increased discharge. The latter may be caused for example by accumulated dirt which gets more conductive at higher humidity.
As a result the effective polarisation voltage may be decreased resulting in increased distortion
I'm not sure if Techspray "Licron Crystal" is available where you live but it's easy to apply, dries clear to about 2 microns thickness, it sounds great in my speakers and I haven't noticed any degradation when it rains. The label says it's not affected by humidity.
Hi MJ,
Thanks for your response. I look inside and I found some traces of maybe insect disintegration. Could that be the case? I'll try to clean them out and try again.
Wachara C.