Re: [altusmetrum] Pyrochannels broken(?)
On a sort of similar note, how many amps at say, 12 volts, can you put through the outputs for say, 1/5 of a second? I can't seem to find any mention of a similar spec in the manual. Bdale sent me this some time ago on this topic, I found it very helpful: The FET switches we're using on all of our current products that have pyro channels are the Vishay Siliconix Si7232DN. These parts have exceptionally low Rds(on) values, better than 0.02 ohms! That means they aren't making a lot of heat... and the limit on current is package limited, meaning it's all about how much you can heat the die before something breaks. Cutting to the chase, the Si7232DN specs are 25 amps *continuous* at 20V at a temperature of 25C. In pulsed mode, they're rated for 40A. However, those specs are a little mis-leading because it really is all about the heat generated... you can get something like 85A through one briefly. Note that a typical commercial e-match only needed about 13 microseconds to fire in tests on my bench a couple years ago! So a great plan is to use something like an e-match as the initiator and build up pyrogen(s) as required to actually light what you're trying to light... But if you want to use a high-current igniter, we can probably handle it! [end of quote] There should be a little piece of wire connecting the 'lipo' screw terminal to the 'pyro' screw terminal. That provides power from the main lipo battery to all of the pyro channels. Yeah, I had this pice of wire inserted. It doesn't make any difference. Also, all other pyro chanels besides Apogee and D show around 4.2 V (or 11.6 V with pyro battery) as they should while at the same time these two chanels show 0.0 V... - Andreas ___ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum
Re: [altusmetrum] Pyrochannels broken(?)
On Thu, Feb 5, 2015 at 2:11 PM, andreas.pah...@gmx.de wrote: Cutting to the chase, the Si7232DN specs are 25 amps *continuous* at 20V at a temperature of 25C. In pulsed mode, they're rated for 40A. However, those specs are a little mis-leading because it really is all about the heat generated... you can get something like 85A through one briefly. Note that a typical commercial e-match only needed about 13 microseconds to fire in tests on my bench a couple years ago! Thanks! -Andrew ___ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum
Re: [altusmetrum] Pyrochannels broken(?)
andreas.pah...@gmx.de writes: Hi guys, one of our TeleMega devices shows a very strange behavior with its pyro channels Apogee and D. Both of them show no continuity, which means 0,00 V reading of the corresponding igniter voltage. If you have a voltmeter, probing around to see if there's actually voltage on the board would be a good thing to do. Also, when fired manually they do nothing at all. That makes me think not. I can't see any damage on neither the board nor the components. Also, the circuit diagram and PCB layout lets me see no direct correlation between the two channels. I agree, this is very strange. Probing the board using a voltmeter with the help of the schematic and PCB artwork may help you figure out what is going on. If not, I can open an RMA for you to send the board back to me for diagnosis and repair if necessary. Bdale signature.asc Description: PGP signature ___ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum
Re: [altusmetrum] Pyrochannels broken(?)
On a sort of similar note, how many amps at say, 12 volts, can you put through the outputs for say, 1/5 of a second? I can't seem to find any mention of a similar spec in the manual. Thanks, -Andrew On Wed, Feb 4, 2015 at 6:36 PM, Keith Packard kei...@keithp.com wrote: andreas.pah...@gmx.de writes: Hi guys, one of our TeleMega devices shows a very strange behavior with its pyro channels Apogee and D. Both of them show no continuity, which means 0,00 V reading of the corresponding igniter voltage. Also, when fired manually they do nothing at all. I can't see any damage on neither the board nor the components. Also, the circuit diagram and PCB layout lets me see no direct correlation between the two channels. Has anyone experienced a similar behavior or suggestions for further testing (or even solutions)? There should be a little piece of wire connecting the 'lipo' screw terminal to the 'pyro' screw terminal. That provides power from the main lipo battery to all of the pyro channels. -- -keith ___ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum ___ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum
Re: [altusmetrum] Pyrochannels broken(?)
andreas.pah...@gmx.de writes: Hi guys, one of our TeleMega devices shows a very strange behavior with its pyro channels Apogee and D. Both of them show no continuity, which means 0,00 V reading of the corresponding igniter voltage. Also, when fired manually they do nothing at all. I can't see any damage on neither the board nor the components. Also, the circuit diagram and PCB layout lets me see no direct correlation between the two channels. Has anyone experienced a similar behavior or suggestions for further testing (or even solutions)? There should be a little piece of wire connecting the 'lipo' screw terminal to the 'pyro' screw terminal. That provides power from the main lipo battery to all of the pyro channels. -- -keith signature.asc Description: PGP signature ___ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum
