Groups > sci.electronics.design > #447335

Re: PNP for soft switch and reverse battery protection

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From	rickman <gnuarm@gmail.com>
Newsgroups	sci.electronics.design
Subject	Re: PNP for soft switch and reverse battery protection
Date	Sat, 11 Feb 2017 18:46:00 -0500
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On 2/11/2017 1:07 PM, Jim Thompson wrote:
> On Sat, 11 Feb 2017 11:38:32 -0600, Peabody
> <waybackNO584SPAM44@yahoo.com> wrote:
>
>> Jim Thompson says...
>>
>>> https://s28.postimg.org/8tdthq4il/Peabody_breadboard.jpg
>>
>>> What is you load current?  I think you're doing
>>> something wrong... don't open the friggin' base!
>>
>> As I said, I changed all the resistors to 47K.  So the base
>> pullup resistor is 47K, the base resistor is 47K, and the
>> load resistor is 47K.  I removed the diode.  And the power
>> supply is 12V.
>>
>> When I insert the transistor backwards, the ON performance
>> is essentially the same as when it's in normal orientation.
>> The base current is about .25mA, and load current is also
>> .25mA, both of which are right for 47K resistors.
>>
>> The problem comes when I try to turn the transistor OFF by
>> disconnecting the base resistor from ground, leaving only
>> the base pullup resistor connected.  If the base pullup is
>> connected to the collector (i.e. - directly to the 12V power
>> supply), I still get 75 uA of current through the load.  If
>> instead I connect the pullup to the emitter as you suggest,
>> the load current increases to 190 uA.  The problem of course
>> is that with the base pullup tied high, the transistor
>> should be completely off, and there shouldn't be any load
>> current at all.
>>
>> The OFF load current only happens if the transistor is in
>> the opposite orientation from normal, and even then only if
>> the power supply is above about 8V (for my 2N3906's at
>> least).
>>
>> Even though this effect doesn't appear to involve the E-B
>> voltage, I do wonder if the Vebo rating of a transistor
>> affects the 8V threshhold.  But I don't have a high-Vebo
>> part to test.
>>
>> If anyone actually breadboards this (not Spice) and
>> gets a different result, please let me know.
>>
>
> What is "motor"?

I believe that is "meter", the thing in series with the voltage source 
on the left.

-- 

Rick C

Thread

PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-09 13:16 -0600
  Re: PNP for soft switch and reverse battery protection John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-09 11:34 -0800
    Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-09 16:47 -0600
      Re: PNP for soft switch and reverse battery protection John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-09 15:40 -0800
        Re: PNP for soft switch and reverse battery protection bitrex <bitrex@de.lete.earthlink.net> - 2017-02-10 10:47 -0500
          Re: PNP for soft switch and reverse battery protection John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-10 08:30 -0800
      Re: PNP for soft switch and reverse battery protection George Herold <gherold@teachspin.com> - 2017-02-10 07:25 -0800
        Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-10 11:37 -0600
          Re: PNP for soft switch and reverse battery protection Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-10 11:19 -0800
            Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 12:48 -0700
            Re: PNP for soft switch and reverse battery protection George Herold <gherold@teachspin.com> - 2017-02-10 12:24 -0800
          Re: PNP for soft switch and reverse battery protection George Herold <gherold@teachspin.com> - 2017-02-10 12:22 -0800
  Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-09 13:21 -0700
    Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-09 16:46 -0600
      Re: PNP for soft switch and reverse battery protection "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-09 17:01 -0600
        Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-09 18:59 -0700
          Re: PNP for soft switch and reverse battery protection "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-10 13:17 -0600
      Re: PNP for soft switch and reverse battery protection Winfield Hill <hill@rowland.harvard.edu> - 2017-02-10 14:29 -0800
        Re: PNP for soft switch and reverse battery protection Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-10 17:58 -0500
          Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 16:40 -0700
      Re: PNP for soft switch and reverse battery protection M Philbrook <jamie_ka1lpa@charter.net> - 2017-02-10 18:23 -0500
  Re: PNP for soft switch and reverse battery protection Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-09 14:55 -0800
  Re: PNP for soft switch and reverse battery protection bill.sloman@ieee.org - 2017-02-09 17:31 -0800
  Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 08:50 -0700
    Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-10 11:18 -0600
      Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 12:41 -0700
        Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-10 16:28 -0600
          Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 16:44 -0700
            Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-10 20:49 -0600
              Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 20:10 -0700
                Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-11 11:38 -0600
                Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-11 11:07 -0700
                Re: PNP for soft switch and reverse battery protection rickman <gnuarm@gmail.com> - 2017-02-11 18:46 -0500
                Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-11 11:15 -0700
                Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-11 18:31 -0600
                Re: PNP for soft switch and reverse battery protection rickman <gnuarm@gmail.com> - 2017-02-11 19:50 -0500
                Re: PNP for soft switch and reverse battery protection Clifford Heath <no.spam@please.net> - 2017-02-12 12:44 +1100
                Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-11 23:26 -0600
                Re: PNP for soft switch and reverse battery protection Clifford Heath <no.spam@please.net> - 2017-02-12 18:19 +1100
                Re: PNP for soft switch and reverse battery protection Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-12 08:18 -0800
                Re: PNP for soft switch and reverse battery protection rickman <gnuarm@gmail.com> - 2017-02-14 01:52 -0500
                Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-11 18:04 -0700
                Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-11 23:14 -0600
                Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-12 08:18 -0700
                Re: PNP for soft switch and reverse battery protection John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-12 08:29 -0800
    Re: PNP for soft switch and reverse battery protection whit3rd <whit3rd@gmail.com> - 2017-02-10 13:54 -0800
  Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-10 08:53 -0700
  Re: PNP for soft switch and reverse battery protection M Philbrook <jamie_ka1lpa@charter.net> - 2017-02-10 18:08 -0500
    Re: PNP for soft switch and reverse battery protection Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-10 15:15 -0800
      Re: PNP for soft switch and reverse battery protection M Philbrook <jamie_ka1lpa@charter.net> - 2017-02-10 18:34 -0500
  Re: PNP for soft switch and reverse battery protection Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-02-11 12:47 -0700
  Re: PNP for soft switch and reverse battery protection Jasen Betts <jasen@xnet.co.nz> - 2017-02-14 06:13 +0000
    Re: PNP for soft switch and reverse battery protection whit3rd <whit3rd@gmail.com> - 2017-02-14 00:52 -0800
      Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-14 22:26 -0600
    Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-14 22:16 -0600
      Re: PNP for soft switch and reverse battery protection John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-14 21:42 -0800
        Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-15 00:21 -0600
          Re: PNP for soft switch and reverse battery protection Jasen Betts <jasen@xnet.co.nz> - 2017-02-15 11:44 +0000
            Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-15 08:15 -0600
              Re: PNP for soft switch and reverse battery protection makolber@yahoo.com - 2017-02-15 09:30 -0800
                Re: PNP for soft switch and reverse battery protection Peabody <waybackNO584SPAM44@yahoo.com> - 2017-02-15 11:50 -0600
                Re: PNP for soft switch and reverse battery protection makolber@yahoo.com - 2017-02-15 10:07 -0800
                Re: PNP for soft switch and reverse battery protection "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-02-15 21:19 -0600
                Re: PNP for soft switch and reverse battery protection George Herold <gherold@teachspin.com> - 2017-02-15 11:30 -0800
                Re: PNP for soft switch and reverse battery protection makolber@yahoo.com - 2017-02-15 11:52 -0800
                Re: PNP for soft switch and reverse battery protection George Herold <gherold@teachspin.com> - 2017-02-15 12:00 -0800
          Re: PNP for soft switch and reverse battery protection John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-15 10:41 -0800

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