Prune said:
Sorry to go OT but... nice quote. Unknown is undoubtedly the wisest person I have ever heard of
Anyway, I think I may still look further into toner as a possibility. Something paintable is another possibility.
what about something much more conductive, like a metalized adhesive?
Do we really need to go for a high resistance diaphram (btw, am I even spelling that right?)? Am I off the path thinking that?
If you're not insulating the stators, you need a high resistance diaphragm in case you hit the limits (and you will!); a low resistance diaphragm will discharge spectacularly, meaning flames and smoke. A high resistance diaphragm under these conditions will just make a small hiss or pop and at worst get a pinhole.
It's a good idea anyway to help you run in constant charge mode. That minimizes distortion.
It's a good idea anyway to help you run in constant charge mode. That minimizes distortion.
I still think quality graphite is the best solution. Another possibility, in case someone hasn't mentioned it, is detergent. Some detergents are slightly conductive even after they dry.
<OT>
johnkramer, I used to have another quote for a sig until the moderators made me change it for being too belligerent. The great physicist Steven Weinberg once said, "Religion is an insult to human dignity. With or without it you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion."
</OT>
<OT>
johnkramer, I used to have another quote for a sig until the moderators made me change it for being too belligerent. The great physicist Steven Weinberg once said, "Religion is an insult to human dignity. With or without it you would have good people doing good things and evil people doing evil things. But for good people to do evil things, that takes religion."
</OT>
I'm confirming that the toner in my laser printer doesn't conduct. I've got an HP printer with an HP cartridge in it.
Possibly a different brand of toner would give different results. Otherwise, it's back to graphite.
Acoustat used the plastic grids from fluorescent lights for frames and glued wires to them. I've never run across a burned Acoustat. The guy I bought my current house from left behind stacks of those grids. The only problem is that they are difficult to damp mechanically, which leads to the "credit card" sound that some complained of.
Come to think of it, they (Acoustat) had some kind of semi-conductive paint that they used. Any thoughts on the composition of that stuff?
Grey
P.S.: Regarding religion...is it not curious that Bush and company are trying to secularize other governments, whilst busily trying to inject as much religion as possible into ours? I wouldn't feel so threatened if it weren't for the fact that theocracies only seem to excel at oppression and conquest. For the life of me, I can't think of a single nation in all of history that has done great things while under theocratic rule.
Maybe I'll move to Australia.
Possibly a different brand of toner would give different results. Otherwise, it's back to graphite.
Acoustat used the plastic grids from fluorescent lights for frames and glued wires to them. I've never run across a burned Acoustat. The guy I bought my current house from left behind stacks of those grids. The only problem is that they are difficult to damp mechanically, which leads to the "credit card" sound that some complained of.
Come to think of it, they (Acoustat) had some kind of semi-conductive paint that they used. Any thoughts on the composition of that stuff?
Grey
P.S.: Regarding religion...is it not curious that Bush and company are trying to secularize other governments, whilst busily trying to inject as much religion as possible into ours? I wouldn't feel so threatened if it weren't for the fact that theocracies only seem to excel at oppression and conquest. For the life of me, I can't think of a single nation in all of history that has done great things while under theocratic rule.
Maybe I'll move to Australia.
Again, I doubt there is any toner out there that conducts. Toners are made of pigment particles that are just about always plastic coated. If you could dissolve away the plastic, the common pigment is carbon black, which is a class 2B (possible human) carcinogen.
Grey, I'm not sure what grids you are talking about. I have a flourescent light in my room and it has no grids. Can you point to a photo?
<OT>Back to the religion thing, PBS has transcripts of two fascinating interviews with Richard Dawkins and Steven Weinberg, who make some insightful observations on the issue.</OT>
Grey, I'm not sure what grids you are talking about. I have a flourescent light in my room and it has no grids. Can you point to a photo?
<OT>Back to the religion thing, PBS has transcripts of two fascinating interviews with Richard Dawkins and Steven Weinberg, who make some insightful observations on the issue.</OT>
Grey: As it happens, the stators in my speakers are Acoustat. The source of the credit-card sound was, I believe, the rather flimsy mounting that Acoustat used. I've got mine mounted in a rather heavy wooden assembly that provides rigidity and some extra baffling, and guess what? No credit card.
In their original diaphragms, Acoustat used a print treated Mylar with a PTF composition painted on it. The PTF appeared to be just a diluted vinyl/carbon black paint. They apparently used a second composition, much more conductive, for the diaphragm lead-out. When I originally got my panels, the coating was cracking and had a lot of pinholes in it. The cracking was worst for the higher conductivity paint. My hope is that the treatment process and composition I used will be more stable than the original. It is certainly a higher resistance.
In their original diaphragms, Acoustat used a print treated Mylar with a PTF composition painted on it. The PTF appeared to be just a diluted vinyl/carbon black paint. They apparently used a second composition, much more conductive, for the diaphragm lead-out. When I originally got my panels, the coating was cracking and had a lot of pinholes in it. The cracking was worst for the higher conductivity paint. My hope is that the treatment process and composition I used will be more stable than the original. It is certainly a higher resistance.
A lot of info can be found here The ESL circuit
Look at the ESL CICUIT/Do it yourself/Projects page. And Materials and Parts has a lot of people selling stuff like mylar and coatings.
On stators.
Most people in Holland that build ESL’s use wire-stators instead of perforated metal. Like this for instance (not mine, but I have something similar). It is a lot of work but easy to do and all you need are a few rolls (say 500m) of wire.
Look at the ESL CICUIT/Do it yourself/Projects page. And Materials and Parts has a lot of people selling stuff like mylar and coatings.
On stators.
Most people in Holland that build ESL’s use wire-stators instead of perforated metal. Like this for instance (not mine, but I have something similar). It is a lot of work but easy to do and all you need are a few rolls (say 500m) of wire.
Even under tension, I doubt these wires are nearly as rigid as a perforated panel. Thus, some of the electric energy would be converted to motion in the wires instead of just the membrane. Would this not be a source of distortion? Depending on their tension, one could imagine them acting like piano strings after a large transient. And how would moving wires affect the electric field?
I must be missing something here, because there are no egg-crates in peterr's link.
Prune,
Surely somewhere on the web there will be a picture of a disassembled Acoustat. The grid I'm describing is white plastic--probably polystyrene--comprised of small squares about 3/4" on a side. It's about 3/4" thick. The panels were 2' by 4.' The stuff cuts easily. I imagine they would have it at Lowe's or Home Depot or whatever you have up your way.
Acoustat glued wires to the grid. I don't know what they used as an adhesive. I built some narrow ESL panels of this nature about 3" wide to use for midranges and had trouble finding a glue that would bind both the insulation on the wire (PVC, as I recall) and the plastic panels. This was a long time ago, and I'm sure there are more choices out there for glues now than I had twenty years ago.
I also had trouble getting the wires straight, but I was too impatient to make a jig and was laying them by hand. Something I'd think would be of possible use here is ordinary aluminum window screen, the kind to keep the bugs out. Cheap, easily available, and close enough meshed to guarantee an even static field. Yes, I realize it's not insulated, so contact with the membrane should be avoided, but then lots of ESLs have used bare metal over the years.
Incidentally, I contrived a direct drive tube circuit to run the thing by modifying an old VM tubed integrated amp. The downfall was that the plastic I was using was too thick/heavy. I keep threatening to go back into the direct drive ESL thing, but it's a low priority at present.
SY,
No argument that Acoustat could have spent another dollar or two making their speakers more rigid.
Diluted black paint might be interesting to follow up on. I might have some old paint that I can use for a resistance test...if I can only remember where I put it.
Grey
Surely somewhere on the web there will be a picture of a disassembled Acoustat. The grid I'm describing is white plastic--probably polystyrene--comprised of small squares about 3/4" on a side. It's about 3/4" thick. The panels were 2' by 4.' The stuff cuts easily. I imagine they would have it at Lowe's or Home Depot or whatever you have up your way.
Acoustat glued wires to the grid. I don't know what they used as an adhesive. I built some narrow ESL panels of this nature about 3" wide to use for midranges and had trouble finding a glue that would bind both the insulation on the wire (PVC, as I recall) and the plastic panels. This was a long time ago, and I'm sure there are more choices out there for glues now than I had twenty years ago.
I also had trouble getting the wires straight, but I was too impatient to make a jig and was laying them by hand. Something I'd think would be of possible use here is ordinary aluminum window screen, the kind to keep the bugs out. Cheap, easily available, and close enough meshed to guarantee an even static field. Yes, I realize it's not insulated, so contact with the membrane should be avoided, but then lots of ESLs have used bare metal over the years.
Incidentally, I contrived a direct drive tube circuit to run the thing by modifying an old VM tubed integrated amp. The downfall was that the plastic I was using was too thick/heavy. I keep threatening to go back into the direct drive ESL thing, but it's a low priority at present.
SY,
No argument that Acoustat could have spent another dollar or two making their speakers more rigid.
Diluted black paint might be interesting to follow up on. I might have some old paint that I can use for a resistance test...if I can only remember where I put it.
Grey
GRollins said:
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dave
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