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#31
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Hash: SHA1 Morgans wrote: "Evan Carew" wrote Well, when last I did this, I remember the RF "bonding" tape was nickel plated coper foil with a collodial silver stickey backing. As I remember, it worked perfectly, if somewhat expensively. Sounds similar to something you can get in the heating and cooling sections of the big box hardware stores. It is thin aluminum tape with sticky on it. Seems like reversing it once in a while, or at the ends would get the al to al contact, to bypass the non conductive sticky. I have a feeling this would suffer from the same problem that riviting suffers from, namely small gaps. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCC4zhpxCQXwV2bJARAkhVAJsGG5pgDcA3y4O8d+wgB4 JoQRTJyQCguxam 8wu9R6NIWX7xfaxKfTh5mqo= =molB -----END PGP SIGNATURE----- |
#32
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Evan Carew wrote:
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Morgans wrote: "Evan Carew" wrote Well, when last I did this, I remember the RF "bonding" tape was nickel plated coper foil with a collodial silver stickey backing. As I remember, it worked perfectly, if somewhat expensively. Sounds similar to something you can get in the heating and cooling sections of the big box hardware stores. It is thin aluminum tape with sticky on it. Seems like reversing it once in a while, or at the ends would get the al to al contact, to bypass the non conductive sticky. I have a feeling this would suffer from the same problem that riviting suffers from, namely small gaps. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCC4zhpxCQXwV2bJARAkhVAJsGG5pgDcA3y4O8d+wgB4 JoQRTJyQCguxam 8wu9R6NIWX7xfaxKfTh5mqo= =molB -----END PGP SIGNATURE----- McMaster Carr sells copper tape 1/4" wide to 3" wide with conductive adhesive. The adhesive surface resistivity is .oo65 ohms/inch. The copper foil is .0014" thick. Adhesive thickness is .0035". A six yard roll varies from ~$6 to $42 depending on width. 1" width sells for ~$15 for six yards part# 76555A714. Gary Thomas |
#33
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Thank you everyone for the input, now I am looking for some
prioritization. I received the new power supply from www.mini-box.com and it is substantially better than the previous version (http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however I still get some noise in the radios. The new version is too big to fit in the previous enclosure so it is sitting slightly apart from the MB on its own. I have started to jot down what the system wants to do, pictures and status at http://69.229.202.54:8080 Under the 'Image' folder one can see the plane, the EPIA in the nose and the prototype ADC board. So now I have a case that has to heavily part for the ATX power lines to come into it & a non cased DC power supply. I have attached ferrite beads to the power lines coming in/out with little improvement. It takes time for many of the steps so I am looking for what you folks think would be the 'biggest bang for the buck', or the right priority to proceed with. (IE, build a brand new case for everything, build a seperate case for the PSU, don't build a case right away but do X,Y,Z, etc..) Thanks once again for the brains helping noodle this over. |
#34
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Hash: SHA1 JC, My comments/questions interspersed with your message: jcpearce wrote: Thank you everyone for the input, now I am looking for some prioritization. I received the new power supply from www.mini-box.com and it is substantially better than the previous version (http://www.mini-box.com/s.nl/sc.8/ca...it.A/id.356/.f ) however I still get some noise in the radios. The new version is too big to fit in the previous enclosure so it is sitting slightly apart from the MB on its own. I have started to jot down what the system wants to do, pictures and status at http://69.229.202.54:8080 Under the 'Image' folder one can see the plane, the EPIA in the nose and the prototype ADC board. So now I have a case that has to heavily part for the ATX power lines to come into it & a non cased DC power supply. I have attached ferrite beads to the power lines coming in/out with little improvement. Stupid question here JC, but it looks like you are using a PC style switching power supply [high noise] to power your standard ATX style PC board. Since most of the important voltages going into an ATX board are either 5V or 12V, why aren't you simply using regulators off the plane's battery to supply the power? It would seem to me to be both cheaper as well as inherently less noisy (not to mention lighter). You wouldn't even have to do any special parts sourcing on these regulators as they are redily available at you local radio shack (karmic regulators anyone?). For a break out of ATX voltages, see the following link: http://www.7volts.com/atx2.jpg It takes time for many of the steps so I am looking for what you folks think would be the 'biggest bang for the buck', or the right priority to proceed with. (IE, build a brand new case for everything, build a seperate case for the PSU, don't build a case right away but do X,Y,Z, etc..) Thanks once again for the brains helping noodle this over. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCD7F5pxCQXwV2bJARAhMmAKCQkWmHv3zP3v1jPgaekZ pWtSSMaQCeLvo9 RfniUGRXnB7y9YA784UsIwg= =zPpX -----END PGP SIGNATURE----- |
#35
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Evan Carew wrote:
board. Since most of the important voltages going into an ATX board are either 5V or 12V, why aren't you simply using regulators off the plane's battery to supply the power? It would seem to me to be both cheaper as well as inherently less noisy (not to mention lighter). You wouldn't even have to do any special parts sourcing on these regulators as they are redily available at you local radio shack (karmic regulators anyone?). You still need the minus voltages hence probably still an inverting power supply. I'd try mounting both in the same case for starters filtering the input 12v supply and see where you need to go from there. John |
#36
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Hash: SHA1 UltraJohn wrote: Evan Carew wrote: board. Since most of the important voltages going into an ATX board are either 5V or 12V, why aren't you simply using regulators off the plane's battery to supply the power? It would seem to me to be both cheaper as well as inherently less noisy (not to mention lighter). You wouldn't even have to do any special parts sourcing on these regulators as they are redily available at you local radio shack (karmic regulators anyone?). You still need the minus voltages hence probably still an inverting power supply. I'd try mounting both in the same case for starters filtering the input 12v supply and see where you need to go from there. John There are many different voltages coming from a power supply. Here is a quick breakdown of what the different voltages do: * -5V - Legacy ISA * -12V - Legacy ISA, Serial Ports (including PS/2) * +3.3V - Motherboard Logic, AGP, PCI * +5V - Motherboard Logic, Drive Logic, PCI, ISA * +12V - Fans, Drive Motors, PCI, ISA -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCD8S/pxCQXwV2bJARApvRAKCLfnctGxRpkQ6AkbF4jtG3i6G8mgCgvm l9 rbKSUS/yb2x5QMbfGlU0skA= =Pjh/ -----END PGP SIGNATURE----- |
#37
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Thanks for the input.
Perhaps going with a linear power supply would be the way to go, I did not as there are already three switching DC-DC power supplies on the MB, the power efficiency is less than 50% for linear and I would have to deal with the heat issues. I could just string a bunch of LM78xx and LM79xx to get the required positive and negative voltages. I've created a seperate smaller case for the PSU as creating a new single case would have taken longer and I don't know about what level of cooling issues I will have. I've noticed the PSU manufacturer (not surprisingly) has reducd the MTBF when it is in hotter conditions. (but hey perhaps I could use the heat to warm my cold toes in the Long Ez) If the weather clears tomorrow I will go flying and measure how much of a problem I have with it operating. Thanks for the continuing input. |
#38
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jcpearce wrote:
Thanks for the input. Perhaps going with a linear power supply would be the way to go, I did not as there are already three switching DC-DC power supplies on the MB, the power efficiency is less than 50% for linear and I would have to deal with the heat issues. I could just string a bunch of LM78xx and LM79xx to get the required positive and negative voltages. I've created a seperate smaller case for the PSU as creating a new single case would have taken longer and I don't know about what level of cooling issues I will have. I've noticed the PSU manufacturer (not surprisingly) has reducd the MTBF when it is in hotter conditions. (but hey perhaps I could use the heat to warm my cold toes in the Long Ez) If the weather clears tomorrow I will go flying and measure how much of a problem I have with it operating. Thanks for the continuing input. The LM79XX's will do you no good unless you have a source of negative voltage to feed them. This generally will mean a dc to dc converter which generally means switching regulators. Try putting your current powersupply in a case and attach it directly to the MB's case and use feedthrough capacitors in the common case bulkheads to feed the dc voltage in. Put fedtrough caps and ferite beads on the dc in to the powersuppply case. Cheep and will get you a good start to eliminating the noise. John |
#39
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John wrote:
jcpearce wrote: Thanks for the input. Perhaps going with a linear power supply would be the way to go, I did not as there are already three switching DC-DC power supplies on the MB, the power efficiency is less than 50% for linear and I would have to deal with the heat issues. I could just string a bunch of LM78xx and LM79xx to get the required positive and negative voltages. I've created a seperate smaller case for the PSU as creating a new single case would have taken longer and I don't know about what level of cooling issues I will have. I've noticed the PSU manufacturer (not surprisingly) has reducd the MTBF when it is in hotter conditions. (but hey perhaps I could use the heat to warm my cold toes in the Long Ez) If the weather clears tomorrow I will go flying and measure how much of a problem I have with it operating. Thanks for the continuing input. The LM79XX's will do you no good unless you have a source of negative voltage to feed them. This generally will mean a dc to dc converter which generally means switching regulators. Try putting your current powersupply in a case and attach it directly to the MB's case and use feedthrough capacitors in the common case bulkheads to feed the dc voltage in. Put fedtrough caps and ferite beads on the dc in to the powersuppply case. Cheep and will get you a good start to eliminating the noise. John About $1.00 a piece from a couple sources I checked. So about $7.00 for the PS voltages plus the dc input. (although some are sold only in 10 lots) if you have multiple projects to use them up in you can order 100 quantity for about $.50 each. John |
#40
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John wrote:
Thanks for the continuing input. The LM79XX's will do you no good unless you have a source of negative voltage to feed them. This generally will mean a dc to dc converter which generally means switching regulators. Try putting your current powersupply in a case and attach it directly to the MB's case and use feedthrough capacitors in the common case bulkheads to feed the dc voltage in. Put fedtrough caps and ferite beads on the dc in to the powersuppply case. Cheep and will get you a good start to eliminating the noise. John About $1.00 a piece from a couple sources I checked. So about $7.00 for the PS voltages plus the dc input. (although some are sold only in 10 lots) if you have multiple projects to use them up in you can order 100 quantity for about $.50 each. John Just checked Newark Catalog They have an interesting item: A feed through teminal block with built-in filter capacitors part # 95F895X where x = number of terminals from 2 to 6. Just something interesting to look into. They have a lot of ideas for cap/ferite/filter ideas. John |
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