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Discussion Groups | BasicX | RE: Digest Number 2752
Discussion forum for the BasicX family of microcontroller chips.
RE: Digest Number 2752 - Lauren Vanderhoof - Aug 10 11:38:51 2007
Ian,
The quick answer is, yes, the BUZ71A power MOSFET is more than adequate
for the purpose at 12A, 50V, Vgs of 4V max and RDSon of 0.12 Ohm.
Connect the Gate to the appropriate pin on the BX-24, the Source to the
common (ground) shared by the BX-24 and the Drain through the nichrome
wire to the main or auxiliary battery.
Having said that a couple of warnings:
1) MOSFETs are extremely sensitive to ESD, so use proper procedures
when handling them.
2) I'd recommend some kind of 'arming' capability. Could be as
simple as a mechanical switch in series with the nichrome wire that is
set to the arm position before launch and after the power to the control
electronics has been turned on, is stable, and the control pin to the
gate has been state to the NOT 'fire' state (presumably 0 V). It was
also mentioned that the nichrome igniter might not be fired if certain
conditions weren't met, so it'd be good to have some way to disarm the
circuit when it comes back down unfired. There may be some others with
more knowledge in this area that can make suitable suggestions.
Regardless, remember Murphy's Law and how things can and do go wrong.
Cheers,
Lauren
________________________________
Will this work:
http://www.allelectronics.com/cgi-bin/item/BUZ71A/search/N-CHANNEL_POWER
_MOSFET,_T0220_.html
Thanks
[Non-text portions of this message have been removed]
(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )
The quick answer is, yes, the BUZ71A power MOSFET is more than adequate
for the purpose at 12A, 50V, Vgs of 4V max and RDSon of 0.12 Ohm.
Connect the Gate to the appropriate pin on the BX-24, the Source to the
common (ground) shared by the BX-24 and the Drain through the nichrome
wire to the main or auxiliary battery.
Having said that a couple of warnings:
1) MOSFETs are extremely sensitive to ESD, so use proper procedures
when handling them.
2) I'd recommend some kind of 'arming' capability. Could be as
simple as a mechanical switch in series with the nichrome wire that is
set to the arm position before launch and after the power to the control
electronics has been turned on, is stable, and the control pin to the
gate has been state to the NOT 'fire' state (presumably 0 V). It was
also mentioned that the nichrome igniter might not be fired if certain
conditions weren't met, so it'd be good to have some way to disarm the
circuit when it comes back down unfired. There may be some others with
more knowledge in this area that can make suitable suggestions.
Regardless, remember Murphy's Law and how things can and do go wrong.
Cheers,
Lauren
________________________________
Will this work:
http://www.allelectronics.com/cgi-bin/item/BUZ71A/search/N-CHANNEL_POWER
_MOSFET,_T0220_.html
Thanks
[Non-text portions of this message have been removed]
(You need to be a member of basicx -- send a blank email to basicx-subscribe@yahoogroups.com )