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design | Re: design help
There are 6 messages in this thread.
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Re: design help - John Larkin - 2009-02-26 19:19:00
On Thu, 26 Feb 2009 18:08:03 -0600, John Fields <j...@austininstruments.com> wrote: >On Thu, 26 Feb 2009 12:48:34 -0800, John Larkin ><j...@highNOTlandTHIStechnologyPART.com> wrote: > > >>>>>>+V>-----------+--------+-----+----+--------+ >>>>>> | | >>>>>> [10k] [COIL] >>>>>> | | >>>>>> | d >>>>>> ____ | diode | >>>>>> O O---+----ak--+-----+----------g-| nfet >>|>>> | | | | >>>>>> | 100uF ~1M s >>>>>> | | | | >>>>>>GND>---+---------------+-----+-------------+ > >Cute. :-) > >Wimpy contact release and consistency, though. > >JF Probably good enough for lots of apps. Turnoff is slow enough that it doesn't need a flyback diode. It can be flipped into a follower, too... >>>>>>+V>-----------+--------+-----+----+--------+ >>>>>> | | >>>>>> [10k] | >>>>>> | | >>>>>> | c >>>>>> ____ | diode | npn >>>>>> O O---+----ak--+-----+----------b-| darl >>|>>> | | | |e >>>>>> | 100uF ~1M coil >>>>>> | | | | >>>>>>GND>---+---------------+-----+-------------+ in which case the relay dropout voltage contributes to the time delay. John
Re: design help - John Larkin - 2009-02-26 19:22:00
On Thu, 26 Feb 2009 17:11:26 -0700, Jim Thompson <T...@My-Web-Site.com> wrote: >On Thu, 26 Feb 2009 15:51:15 -0800, John Larkin ><j...@highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 26 Feb 2009 13:35:10 -0600, John Fields >><j...@austininstruments.com> wrote: >> >>>On Thu, 26 Feb 2009 08:45:47 -0800, John Larkin >>><j...@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Thu, 26 Feb 2009 10:32:55 -0600, John Fields >>>><j...@austininstruments.com> wrote: >>>> >>>>>On Thu, 26 Feb 2009 09:14:12 -0600, John Fields >>>>><j...@austininstruments.com> wrote: >>>>> >>>>> >>>>>>--- >>>>>>But... something esle was running around in my head and here it is: >>>>>>a _much, much_ better way to do it, Duh... >>>>>> >>>>>> >>>> >>>>Or just... >>>> >>>> >>>>>>+V>-----------+--------+-----+----+--------+ >>>>>> | | >>>>>> [1M] [COIL] >>>>>> | | >>>>>> | e >>>>>> ____ | / -----b pnp darlington or >>>>>> O O---+------------------/ c low threshold pfet >>>>>> | | | >>>>>> | [68µF] | >>>>>> | | | >>>>>>GND>---+------+--------+-----+-------------+ >>> >>>--- >>>Huh??? >>> >>>RTFM >>> >>>JF >> >>Keep working on your 555 thing. If you add enough parts, you may >>eventually get it right. >> >>John > >John L, Methinks you need to revisit the original SOW, before >throwing stones... > >"I'm ok with fixing and adapting circuits but not so good with design. >I've come up with an electronic switch circuit but I think it could >use improvement. The goal is to turn on a 12v relay with a switch >that is closed when off and open when on. The switch also has to have >one leg grounded. It's a pressure switch with a single terminal. I >also want the relay to stay closed (on) for a couple minutes when the >switch goes from on (open) to off (closed). Here's what I've got now >and it does work. But I had to use a pretty big capacitor and I'm >still only getting about a minute of delay when going to the off >state. Because I can't make the 10k resistor any bigger. I'm >thinking that it is likely possible to get a longer delay and do it >with a smaller capacitor if I was better at designing this. The other >flaw is that this slowly lowers the voltage to the relay until it >drops. The relay stays pulled to about 3 to 4 volts. I also suspect >there is a better way to keep it fully on until the rc timer expires. >Thanks in advance for any suggestions :-)" > > > ...Jim Thompson I'm sure you and Rich will post some great circuits and show us how wrong we are. John
Re: design help - John Larkin - 2009-02-26 21:11:00
On Thu, 26 Feb 2009 18:23:57 -0700, Jim Thompson <T...@My-Web-Site.com> wrote: >On Thu, 26 Feb 2009 19:11:49 -0600, John Fields ><j...@austininstruments.com> wrote: > >>On Thu, 26 Feb 2009 12:50:56 -0800, John Larkin >><j...@highNOTlandTHIStechnologyPART.com> wrote: >> >[snip] >>> >>>The original description wasn't a model of clarity. >> >>--- >>Onward through the fog. Seems a couple of us got it, you not included, >>first time out. >>--- >> >>>But if you keep score and rejoice in mistakes, enjoy. >> >>--- >>Oh, my... how passive aggressive. > >Bwahahahahaha! Damn! Almost snorted wine up my nose :-( > >> >>A guilt trip you'd like to have laid on us for finding "the Larkin" at >>fault? >> >>It's not about rejoicing in mistakes, its about rejoicing in catching >>those who profess to be free from making mistakes and, when they do, >>blaming it on someone else. >> >>Your: "The original description wasn't a model of clarity." is a prime >>example, since you blamed the OP for _your_ inability to understand what >>he was talking about, while at least two of us did. >> >>JF > >Bwahahahahahaha! > > ...Jim Thompson TWO old hens. John
Re: design help - John Fields - 2009-02-27 08:43:00
On Thu, 26 Feb 2009 18:11:32 -0800, John Larkin <j...@highNOTlandTHIStechnologyPART.com> wrote: >On Thu, 26 Feb 2009 19:11:49 -0600, John Fields ><j...@austininstruments.com> wrote: > >>On Thu, 26 Feb 2009 12:50:56 -0800, John Larkin >><j...@highNOTlandTHIStechnologyPART.com> wrote: >> >>>On Thu, 26 Feb 2009 19:28:44 GMT, Rich Grise <r...@example.net> wrote: >>> >>>>On Thu, 26 Feb 2009 17:13:40 +0000, James Arthur wrote: >>>>>... >>>>> Maybe I misunderstood, >>>> >>>>Nope. >>>> >>>>> but wasn't the goal to engage a >>>>> relay when a switch opens, then release the relay a minute >>>>> or two or three after the switch re-closes? >>>> >>>>Yup: >>>>"The goal is to turn on a 12v relay with a switch that is closed when off >>>>and open when on." >>>> >>>>O frabjous day! Callooh! Callay! Both Johns have scresed one up today! >>>>;-D >>>> >>> >>>The original description wasn't a model of clarity. >> >>--- >>Onward through the fog. Seems a couple of us got it, you not included, >>first time out. >>--- >> >>>But if you keep score and rejoice in mistakes, enjoy. >> >>--- >>Oh, my... how passive aggressive. >> >>A guilt trip you'd like to have laid on us for finding "the Larkin" at >>fault? >> >>It's not about rejoicing in mistakes, its about rejoicing in catching >>those who profess to be free from making mistakes and, when they do, >>blaming it on someone else. > >I make mistakes all the time, some here. And I freely admit the ones >that are obvious. We just sometimes disagree on what's actually a >mistake. > >> >>Your: "The original description wasn't a model of clarity." is a prime >>example, since you blamed the OP for _your_ inability to understand what >>he was talking about, while at least two of us did. >> >>JF > >Get a life. You're turning into an old hen, strutting and clucking. > >If I misunderstood the OP's polarities, so what? --- You didn't just misunderstand the polarities, you misunderstood the circuit's raison d'ętre. Big difference. Besides, you're the one who's always preaching about being careful, checking your work, etc., etc., etc., so it seems sort of hypocritical that you'd give this app a lick and a promise. --- >Get a life. --- Translation "Get out of my face." Even if mine doesn't please you, it does me, which is what matters. JF
Re: design help - John Larkin - 2009-02-27 10:00:00
On Fri, 27 Feb 2009 06:42:57 -0600, John Fields <j...@austininstruments.com> wrote: >On Thu, 26 Feb 2009 15:51:15 -0800, John Larkin ><j...@highNOTlandTHIStechnologyPART.com> wrote: > >>On Thu, 26 Feb 2009 13:35:10 -0600, John Fields >><j...@austininstruments.com> wrote: >> >>>On Thu, 26 Feb 2009 08:45:47 -0800, John Larkin >>><j...@highNOTlandTHIStechnologyPART.com> wrote: >>> >>>>On Thu, 26 Feb 2009 10:32:55 -0600, John Fields >>>><j...@austininstruments.com> wrote: >>>> >>>>>On Thu, 26 Feb 2009 09:14:12 -0600, John Fields >>>>><j...@austininstruments.com> wrote: >>>>> >>>>> >>>>>>--- >>>>>>But... something esle was running around in my head and here it is: >>>>>>a _much, much_ better way to do it, Duh... >>>>>> >>>>>> >>>> >>>>Or just... >>>> >>>> >>>>>>+V>-----------+--------+-----+----+--------+ >>>>>> | | >>>>>> [1M] [COIL] >>>>>> | | >>>>>> | e >>>>>> ____ | / -----b pnp darlington or >>>>>> O O---+------------------/ c low threshold pfet >>>>>> | | | >>>>>> | [68µF] | >>>>>> | | | >>>>>>GND>---+------+--------+-----+-------------+ >>> >>>--- >>>Huh??? >>> >>>RTFM >>> >>>JF >> >>Keep working on your 555 thing. If you add enough parts, you may >>eventually get it right. > > >Maybe, but you certainly don't have any room to criticize, what with the >paucity of parts on that abomination above. "Paucity of parts"? I'm trying to come up with the simplest circuit that will work, and you're trying to come up with the most complex one. Different design goal. John
Re: design help - Rich Grise - 2009-02-28 16:46:00
On Thu, 26 Feb 2009 18:11:58 -0800, John Larkin wrote: > On Thu, 26 Feb 2009 18:23:57 -0700, Jim Thompson >>On Thu, 26 Feb 2009 19:11:49 -0600, John Fields >>>Your: "The original description wasn't a model of clarity." is a prime >>>example, since you blamed the OP for _your_ inability to understand >>>what he was talking about, while at least two of us did. >> >>Bwahahahahahaha! > > TWO old hens. And one Polly Prissypants. ;-) Cheers! Rich