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#51
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Hash: SHA1 As a general rule, if you are thinking of solidifying such a design, you generally go out & purchase one of those hardened PC systems such as PC104 or like. These systems come with features such as extended temperature ranges, G tested, & slower clock rates so you don't have to use fans. Most of the systems I have seen in this class also have slots for CF cards & can get by on ~15 watts of power, or just about what your average night light is rated for. Evan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCFO6ipxCQXwV2bJARAoijAJ9uyFiGJsaghTBrb0hH+X cGVmSncwCfaoSK 0zoNS5oI56uVEBP39MDuFcA= =KaXv -----END PGP SIGNATURE----- |
#52
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Thanks everyone. A brief update.
With the new power supply the mini itx people sent me the problem almost went away, I was able to do flight tests with it but .... very rarely it would still cause enough interference to cut into the Radio's, something clearly unacceptable as sooner or later it would happen when the tower would be talking to me. So I suppose I will pursue the linear regulator route. John you mentioned there was an IC to take 12V and invert it to -12v, do you know the part #? Before I read the recent post I had all the TO-3's to make one and was going to try and just omit the -12V and see what happens as I could not find out what this was used for, but I see in the posts it is used for serial communication which I do use. The ADC board I built sends over the sensors data via serial and I log all the GPS NMEA data via serial. I like the idea of linear regulators, low noise and a low part count. There should not be a heat problem as the nose of the Long EZ has circulating air (which is a bane at high altitudes). Looking at the ATX power supply specifications they state there is a sequencing of voltages and when everything is OK, a PW_OK line is dropped low. I would rather not get into sequencing and keep as much as possible to the K.I.S.S. mindset. Does anyone have an idea on whether this is truly important? I was hoping to just apply power and be ready. Thanks again to everyone and the recent replies from John, Evan & UltraJohn Evan Carew wrote: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 As a general rule, if you are thinking of solidifying such a design, you generally go out & purchase one of those hardened PC systems such as PC104 or like. These systems come with features such as extended temperature ranges, G tested, & slower clock rates so you don't have to use fans. Most of the systems I have seen in this class also have slots for CF cards & can get by on ~15 watts of power, or just about what your average night light is rated for. Evan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCFO6ipxCQXwV2bJARAoijAJ9uyFiGJsaghTBrb0hH+X cGVmSncwCfaoSK 0zoNS5oI56uVEBP39MDuFcA= =KaXv -----END PGP SIGNATURE----- |
#53
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jcpearce wrote:
Thanks everyone. A brief update. With the new power supply the mini itx people sent me the problem almost went away, I was able to do flight tests with it but .... very rarely it would still cause enough interference to cut into the Radio's, something clearly unacceptable as sooner or later it would happen when the tower would be talking to me. So I suppose I will pursue the linear regulator route. John you mentioned there was an IC to take 12V and invert it to -12v, do you know the part #? snip Looking at the ATX power supply specifications they state there is a sequencing of voltages and when everything is OK, a PW_OK line is dropped low. I would rather not get into sequencing and keep as much as possible to the K.I.S.S. mindset. Does anyone have an idea on whether this is truly important? I was hoping to just apply power and be ready. Thanks again to everyone and the recent replies from John, Evan & UltraJohn http://www.jameco.com/Jameco/catalogs/c251/P38.pdf This is one chip its a higher power version of the ICL7660/7662 TC962CPA Converts +voltage to -voltage ie +12v to -12 volts or +5 volts to -5 volts. About $2.50 a piece in single quantities. They do use switching but with the low power should not be the problem that the high power switchers in the +5 atx power supplies. I think they're rated at 80ma 95+% efficiency it should be enough for rs232. Also check weather your video uses - voltages it probably does. Put an ampmeter in series with your - powersupplies to see what draw it needs. As far as pw_ok is you could probably use a generic pnp transistor such as an 2n2222 with a resistor from the + voltage to the collector, ground the emitter and then a resistor from the + voltage to the base and a 10uf+ capacitor from the base to ground. connect the collector to the pw_ok. This would keep the collector (pw_ok) high till the capacitor charged enough the it would go to ground. You could also use a generic ic inverter to do the same thing. Hope this helps. John ps via has a board similiar to what your running but it is designed from scratch to run from just 12v it retails for $183.00. |
#54
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"jcpearce" wrote in message ups.com... 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. Check out this machine, only +5vdc required, linux capable... http://www.diamondsystems.com/products/prometheus I'm sure there are many more similar... |
#55
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Hash: SHA1 Blueskies wrote: "jcpearce" wrote in message ups.com... 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. Check out this machine, only +5vdc required, linux capable... http://www.diamondsystems.com/products/prometheus I'm sure there are many more similar... All Right! Now that's what I call an embedded system. Actually I use systems almost exactly the same as these in my line of work... Put Linux on them too. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCFqZ1pxCQXwV2bJARAq0WAKCQoWnkN5Ncza2Q/smCjFLG3+Xs4wCgi6Gx EoJRK6xJaoaAcln6lG69Hcg= =8+p8 -----END PGP SIGNATURE----- |
#56
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Blueskies wrote:
Check out this machine, only +5vdc required, linux capable... http://www.diamondsystems.com/products/prometheus I'm sure there are many more similar... Looks to be a nice system to play around with. It has the possibility of handling both the data interface and computations. The main problem I see with this system is no windowing system ie KDE and I think that was part of his need. John |
#57
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Hope this helps. John ps via has a board similiar to what your running but it is designed from scratch to run from just 12v it retails for $183.00. Product info: http://www.logicsupply.com/product_i...roducts_id/174 VIA EPIA TC10000 Mini-ITX Motherboard (on-board DC-DC converter) $183.00 The ultimate platform for low profile networked devices, integrating an onboard 12V DC-DC converter and horizontal SODIMM for complete system design flexibility. Measuring 17 x 17cm, the ultra compact VIA EPIA TC Mini-ITX Mainboard is a highly integrated and configurable x86 platform with rich connectivity and multimedia options that enables the development of a wealth of small, slim and low noise networked systems. The rich built-in feature set of the VIA EPIA TC alleviates the need for system developers to source extra components, reducing cost and time to market. VIA EPIA TC Specifications • VIA C3™ processor • VIA CLE266 North Bridge, VT8235 South Bridge chipset • 1 x 200-pin DDR266 SODIMM memory socket, up to 1GB • Integrated VIA UniChrome™ 2D/3D graphics with integrated MPEG-2 accelerator, motion compensation and DuoView support • 1 PCI Expansion Slot • 2 x UltraDMA 133/100/66 IDE connectors, direct DOM support (VCC set to 5V/3.3V on the 20th pin) • 12V, 5V, 60W Max onboard DC-DC Converter • VIA Networking Tahoe VT6103 Fast Ethernet 10/100 PHY-ceiver onboard LAN • VIA VT1612A 2-channel AC'97 codec onboard Audio • Onboard I/O Connectors: 2 USB connectors for 4 additional USBv2.0 ports, 1 Front-panel audio connectors (mic-in and line-out), 1 Serial port header, 1 LPT port-connector, 1 CIR connector (Switchable for KB/MS), Wake-on LAN connector, 2 Fan connectors CPU/Sys FAN, 1 + 12V power connector • Back Panel I/O: 1 DC-in jack, 1 PS2 mouse port, 1 PS2 keyboard port, 1 RJ-45 LAN port, 1 Serial port, 2 USB 2.0 ports, 1 VGA port, 3 Audio jacks: line-out, line-in and mic-in • Mini-ITX (4 layer) form factor 17 cm x 17 cm (6.7” x 6.7”) Additional Information: • This motherboard has an integrated DC-DC power converter wich needs a 12V power supply. ONLY use a 12V, 5A (60W) power supply with this board. If you plan on using this motherboard in a car or boat, you will need to use a power stabilizer. |
#58
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I built a test linear regulator power supply this evening and the TO-3
regulator bringing ~12v down to 3.3 Volts nearly burnt a hole in the test board. I looked over the wiring which was OK so it looks like the thermal output of bringing 12volts down to 3.3 for 3 amps is just way too high. So so much for that idea (unless I am missing something) I may just end up getting on the EPIA TC models as UltraJohn mentioned and hope that their EMI/RFI solution is better. The plane battery voltage is ~12volts idle and ~14 volts running, what is a way of doing the "power stabilizing" necessary for the EPIA TC which requires 11.6-12.4 Volts? If I just put a 12V linear regulator on there the drop off in voltage would prevent the system running off battery. |
#59
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How much does one of these development systems cost? Check out this machine, only +5vdc required, linux capable... http://www.diamondsystems.com/products/prometheus I'm sure there are many more similar... |
#60
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 jcpearce wrote: I built a test linear regulator power supply this evening and the TO-3 regulator bringing ~12v down to 3.3 Volts nearly burnt a hole in the test board. I looked over the wiring which was OK so it looks like the thermal output of bringing 12volts down to 3.3 for 3 amps is just way too high. So so much for that idea (unless I am missing something) I may just end up getting on the EPIA TC models as UltraJohn mentioned and hope that their EMI/RFI solution is better. The plane battery voltage is ~12volts idle and ~14 volts running, what is a way of doing the "power stabilizing" necessary for the EPIA TC which requires 11.6-12.4 Volts? If I just put a 12V linear regulator on there the drop off in voltage would prevent the system running off battery. JC, Look at the specs for the part. They often require X many square inches of copper, or equavelent in a heat sink to disipate the thermal energy they throw away. Evan -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFCFz1ipxCQXwV2bJARAovDAKDKOkN1Gy5Q/cGya6uLaOOLOtjHKACgqokZ 560wu/RjK/LtNav/eepuZrs= =scfz -----END PGP SIGNATURE----- |
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