Big crowbar module for <4VDC?
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From: Jim Thompson on 19 Dec 2008 09:52 On Thu, 18 Dec 2008 18:53:34 -0800, Joerg <notthisjoergsch(a)removethispacbell.net> wrote: >Jim Thompson wrote: >> On Thu, 18 Dec 2008 18:32:11 -0800, Joerg >> <notthisjoergsch(a)removethispacbell.net> wrote: >> >> [snip] >>> The proper way to do a crowbar is with a TL431. >>> >>> [...] >> >> Of course. TL431 was one of my jelly-bean-parts-of-choice during the >> mid '70's thru late '80's. >> > >With me they still are. When I feel extra generous I might even spring >for a TLV431 on regular circuits (not crowbars), but not often. I roll my own versions of TL431 now ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine Sometimes I even put it in the food
From: Jim Thompson on 19 Dec 2008 09:53 On Fri, 19 Dec 2008 10:51:25 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Thu, 18 Dec 2008 18:32:11 -0800) it happened Joerg ><notthisjoergsch(a)removethispacbell.net> wrote in ><TID2l.10279$yr3.2278(a)nlpi068.nbdc.sbc.com>: > >>> http://www.hobbyprojects.com/thyristor_triac_and_diac/thyristor_as_a_crowbar.html >>> >> >>Has the author ever heard of a gate trigger voltage? Assume 1.5V for >>now: Zener 5.1V plus Vgt = 6.6V. Phssst ... crackle ... pop ... *BANG* >>... there goes the majority of connected logic chips. Many of those >>won't take anything above 6V. >> >>The proper way to do a crowbar is with a TL431. > >Crowbars are to protect the LOAD, not the supply, and should be at the OUTPUT. >In case of a 100K$ load and a 100$ supply, the choice is easy. >Shorting before the regulator does not guarantee energy in any caps and >or inductors in the circuit does not make it to the load. >Simple. Nope. Simple-minded analysis. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine Sometimes I even put it in the food
From: Jim Thompson on 19 Dec 2008 09:55 On Fri, 19 Dec 2008 10:51:25 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote: >On a sunny day (Thu, 18 Dec 2008 18:32:11 -0800) it happened Joerg ><notthisjoergsch(a)removethispacbell.net> wrote in ><TID2l.10279$yr3.2278(a)nlpi068.nbdc.sbc.com>: > >>> http://www.hobbyprojects.com/thyristor_triac_and_diac/thyristor_as_a_crowbar.html >>> >> >>Has the author ever heard of a gate trigger voltage? Assume 1.5V for >>now: Zener 5.1V plus Vgt = 6.6V. Phssst ... crackle ... pop ... *BANG* >>... there goes the majority of connected logic chips. Many of those >>won't take anything above 6V. >> >>The proper way to do a crowbar is with a TL431. > >Crowbars are to protect the LOAD, not the supply, and should be at the OUTPUT. >In case of a 100K$ load and a 100$ supply, the choice is easy. >Shorting before the regulator does not guarantee energy in any caps and >or inductors in the circuit does not make it to the load. >Simple. But, according to Joerg, $1 for a fuse is too much ;-) ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine Sometimes I even put it in the food
From: Jan Panteltje on 19 Dec 2008 10:06 On a sunny day (Fri, 19 Dec 2008 07:53:00 -0700) it happened Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote in <q9dnk45qjgfe4u4upnc3a7kvpivet4f0r1(a)4ax.com>: >On Fri, 19 Dec 2008 10:51:25 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: >>Crowbars are to protect the LOAD, not the supply, and should be at the OUTPUT. >>In case of a 100K$ load and a 100$ supply, the choice is easy. >>Shorting before the regulator does not guarantee energy in any caps and >>or inductors in the circuit does not make it to the load. >>Simple. > >Nope. Simple-minded analysis. Maybe you can address this issue: 'Shorting before the regulator does not guarantee energy in any caps and or inductors in the circuit does not make it to the load.' versus insulting, you leftist commie ;-) My view is: Measure temperature where you want to know it, Measure voltage where you want to know it. And limit voltage where you want it limited, not at the power plant LOL.
From: Jan Panteltje on 19 Dec 2008 10:14
On a sunny day (Fri, 19 Dec 2008 07:55:41 -0700) it happened Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote in <cednk493j5aj8ncfdgsm1tb4kjbk2d15pp(a)4ax.com>: >On Fri, 19 Dec 2008 10:51:25 GMT, Jan Panteltje ><pNaonStpealmtje(a)yahoo.com> wrote: > >>On a sunny day (Thu, 18 Dec 2008 18:32:11 -0800) it happened Joerg >><notthisjoergsch(a)removethispacbell.net> wrote in >><TID2l.10279$yr3.2278(a)nlpi068.nbdc.sbc.com>: >> >>>> http://www.hobbyprojects.com/thyristor_triac_and_diac/thyristor_as_a_crowbar.html >>>> >>> >>>Has the author ever heard of a gate trigger voltage? Assume 1.5V for >>>now: Zener 5.1V plus Vgt = 6.6V. Phssst ... crackle ... pop ... *BANG* >>>... there goes the majority of connected logic chips. Many of those >>>won't take anything above 6V. >>> >>>The proper way to do a crowbar is with a TL431. >> >>Crowbars are to protect the LOAD, not the supply, and should be at the OUTPUT. >>In case of a 100K$ load and a 100$ supply, the choice is easy. >>Shorting before the regulator does not guarantee energy in any caps and >>or inductors in the circuit does not make it to the load. >>Simple. > >But, according to Joerg, $1 for a fuse is too much ;-) Joerg uses narrower PCB traces as fuse perhaps? |