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mildred
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Post subject: Multimeter questions  Posted: Sat Jan 16, 2010 8:56 pm |
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Joined: Sun Dec 27, 2009 8:48 pm
Posts: 19
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COMPAQ- is the brand of computor-perhaps same as HP I don't know. Scott mentioned in his 18th. edition about useing a multimeter in testing voltages in a computor, is it a high Z model? I still have a V.T.V.M. that has a 100,000 ohm per volt impedance with a wheatstone bridge built in. most multimeters I have owned are rather low Z about 20,000 ohm per volt, which can load down a delicate system. _ carl
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Scott
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Post subject: Re: Vista and intenet explorer script errors Posted: Sun Jan 17, 2010 8:56 am |
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Joined: Sun Feb 04, 2007 11:44 am
Posts: 6114
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You can use any type of voltmeter on a computer. Old style analog ohm meters however (e.g. those with internal 9V batteries) should not be used on digital circuits. For measuring resistance, use a modern digital VOM instead. Scott.
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mildred
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Post subject: Re: Multimeter questions Posted: Sun Jan 17, 2010 6:38 pm |
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Joined: Sun Dec 27, 2009 8:48 pm
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Dear Scott, I have a Digital meter that talks to me so I don't have to take my eyes off what I have the Probe on. It is also has a 7 Segment Liquad Crystal Display, I have never had it apart, so what powers the LCD if it does not have batterries or battery in it ?- Carl
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Scott
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Post subject: Re: Multimeter questions Posted: Sun Jan 17, 2010 8:05 pm |
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Joined: Sun Feb 04, 2007 11:44 am
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Your meter sounds fine, you just don't want one that uses 9V batteries. Scott.
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mildred
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Post subject: Re: Multimeter questions Posted: Mon Jan 18, 2010 12:31 pm |
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Joined: Sun Dec 27, 2009 8:48 pm
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Dear Scott I see where you are coming from, Most resistors etc. are double rated in voltage etc. Back when I was being schooled in Tech School, I am not disagreeing , just stateing what I was taught, I agree that 3- 5 volt powered meter is safer, The V.T.V.M. only used a 1 1/2 volt battery= Thanks For your prompt and polite answers !- Carl
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spiderman
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Post subject: Re: Multimeter questions Posted: Wed Sep 27, 2017 2:01 am |
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Joined: Wed Jun 01, 2011 11:59 am
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mildred wrote: Your meter sounds fine, you just don't want one that uses 9V batteries. Scott. scott Why don't you want to use a meter with a 9v batteries?
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spiderman
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Post subject: Re: Vista and intenet explorer script errors Posted: Wed Sep 27, 2017 2:06 am |
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Joined: Wed Jun 01, 2011 11:59 am
Posts: 468
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Scott wrote: You can use any type of voltmeter on a computer. Old style analog ohm meters however (e.g. those with internal 9V batteries) should not be used on digital circuits. For measuring resistance, use a modern digital VOM instead. Scott. What are digital circuits? is a voltmemter same as a mutiltmeter?
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Scott
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Post subject: Re: Vista and intenet explorer script errors Posted: Wed Sep 27, 2017 10:28 pm |
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spiderman wrote: What are digital circuits? Digital circuits are binary circuits in a computer that typically work on switching 5V (or lower voltage) signals. Compare this to analog circuits, which use continuously variable signals of any voltage level. Quote: ...is a voltmemter same as a mutiltmeter? A voltmeter measures voltage. A multimeter measures voltage, current and resistance. Multimeters include a voltmeter. Quote: Why don't you want to use a meter with a 9v batteries? Because only older (mostly analog) multimeters use 9V batteries and injecting 9V into a circuit that runs on only 3V or less may cause damage. Scott.
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spiderman
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Post subject: Re: Multimeter questions Posted: Fri Oct 13, 2017 3:29 am |
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Joined: Wed Jun 01, 2011 11:59 am
Posts: 468
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Quote: Because only older (mostly analog) multimeters use 9V batteries and injecting 9V into a circuit that runs on only 3V or less may cause damage. Now would this be also with a digital multimeters that use a 9v batteries as well. have you seen a 9v batteries that is higher then 9v like 10v what is the deal with that. I test a new 9V battery and it shows as 10v on three meters.... weird...
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Scott
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Post subject: Re: Multimeter questions Posted: Fri Oct 13, 2017 8:44 am |
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Joined: Sun Feb 04, 2007 11:44 am
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spiderman wrote: Now would this be also with a digital multimeters that use a 9v batteries as well. Any digital multimeter would be fine no matter what battery it used. Quote: have you seen a 9v batteries that is higher then 9v like 10v what is the deal with that. I test a new 9V battery and it shows as 10v on three meters.... The zero-load voltage of an alkaline battery can be up to 1.65V. Since a 9V battery has 6 cells it can show a no-load voltage of up to 9.9V
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FatGuy
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Post subject: Re: Multimeter questions Posted: Fri Oct 13, 2017 3:44 pm |
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Joined: Tue May 08, 2007 8:54 pm
Posts: 1780
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Scott. I have Radioshack Digital Auto Ranging Multimeter. It's Catalog no. 22-801. This is the only thing I could find on it. I still have the manual and everything. I don't remember when I purchased it but it does have a 9 Volt battery. I assume it's fine. I just opened it up today to check it out. I changed the battery and it seems to power up fine. Only remember using it once to try "back-probing" a PSU as described in your book. I'm guessing you really miss RadioShack Scott.
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Scott
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Post subject: Re: Multimeter questions Posted: Fri Oct 13, 2017 8:30 pm |
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Joined: Sun Feb 04, 2007 11:44 am
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That meter should be fine. I have been a customer of Radio Shack since the early 1970s and even worked at a store for a short time in the early '80s. They are an American institution. While they are not gone they are not what they used to be (but neither is anything else): https://www.radioshack.com/
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