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The Simpson 260

Started by John S June 19, 2015
I have many instruments. The most valued and cherished one is the 
Simpson 260. I can easily do some things with it that is almost 
impossible with a DVM, oscilloscope, etc. I hope I never have to do 
without it.
I have a Simpson 260, and I agree. It's almost as good as my Avometer 8 Mk IV, which is the best analogue MM ever built. (And which I'm using today.)

Cheers

Phil Hobbs
On Friday, June 19, 2015 at 8:55:01 AM UTC-4, John S wrote:
> I have many instruments. The most valued and cherished one is the > Simpson 260. I can easily do some things with it that is almost > impossible with a DVM, oscilloscope, etc. I hope I never have to do > without it.
OK What kind of things? I used a Simpson in the past. but now just struggle along with my 'scope and DMM. :^) George H.
On 6/19/2015 8:20 AM, George Herold wrote:
> On Friday, June 19, 2015 at 8:55:01 AM UTC-4, John S wrote: >> I have many instruments. The most valued and cherished one is the >> Simpson 260. I can easily do some things with it that is almost >> impossible with a DVM, oscilloscope, etc. I hope I never have to do >> without it. > > OK What kind of things? I used a Simpson in the past. but now just > struggle along with my 'scope and DMM. :^) > > George H. >
Well, being analog, I can watch fluctuations on the pointer rather than an undecipherable display of rapidly changing digits. In other words, it inherently integrates the readings. I can see when my board's processor wakes up and handles things by the blip, if it is long enough to see it on the pointer. With a DVM, it looks like a momentary problem. I have used it to test the function of transformers by noticing the apparent change in resistance when the probes are applied. Transformers have a relatively large inductance and when the meter is applied, the resistance reads high momentarily and then drops to the dc value. The larger the inductance, the longer it takes to change. Therefore, the inductance is relatively good if there are no short circuits. When I was working on 460V inverters, it was the best tool I had in my arsenal. DVMs are better for accuracy, but for utility, I like the 260.
On Fri, 19 Jun 2015 07:54:55 -0500, John S <Sophi.2@invalid.org>
wrote:

>I have many instruments. The most valued and cherished one is the >Simpson 260. I can easily do some things with it that is almost >impossible with a DVM, oscilloscope, etc. I hope I never have to do >without it.
Haven't used one for 20+ years and don't miss it much, except maybe low ohms range. Reminds me I should dust off that big-meter analog milliohmeter I got for almost free at an auction.. just needs a modern replacement for the Hg batteries. -- Best regards, Spehro Pefhany Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8 Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48
On Fri, 19 Jun 2015 10:09:13 -0400, Spehro Pefhany
<speffSNIP@interlogDOTyou.knowwhat> wrote:

>On Fri, 19 Jun 2015 07:54:55 -0500, John S <Sophi.2@invalid.org> >wrote: > >>I have many instruments. The most valued and cherished one is the >>Simpson 260. I can easily do some things with it that is almost >>impossible with a DVM, oscilloscope, etc. I hope I never have to do >>without it. > >Haven't used one for 20+ years and don't miss it much, except maybe >low ohms range.
Ditto. It's been so long that I have to think about the switch setting and the ranges to read the right value off the meter. I used to do that automatically. I'm getting lazy, expecting the meter to show me decimal millivolts or whatever. My Keithley really takes thinking, what with the multipliers https://dl.dropboxusercontent.com/u/53724080/Gear/Keithley/Keithley.JPG The low input impedance of an old VOM can be a mixed blessing. Analog scopes confuse me now too. All of the traces are the same color! Mo found this at a flea market and gave it to me https://dl.dropboxusercontent.com/u/53724080/Gear/HF_Ammeter.JPG It's probably thermocouple based. -- John Larkin Highland Technology, Inc picosecond timing laser drivers and controllers jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Fri, 19 Jun 2015 06:20:03 -0700 (PDT), George Herold
<gherold@teachspin.com> wrote:

>OK What kind of things? I used a Simpson in the past. but now just >struggle along with my 'scope and DMM. :^) >George H.
<http://simpson260.com> Note that the Simpson 260-8 is still being made and sold: <http://www.simpsonelectric.com/products/test-equipment/vom-multimeters/260-8-260-8p> <http://www.simpsonelectric.com/products/test-equipment/vom-multimeters/260-8xi-260-8xpi> <http://www.stanleysupplyservices.com/simpson-model-260-8-v-o-m/g/1031> I have several and use them occasionally for tuning commercial land mobile radios when I can't find where my official test set is hiding. This is an old photo of my bench, but it's the 2nd instrument from the right: <http://802.11junk.com/jeffl/pics/home/slides/BL-shop1.html> The nice thing about an analog meter is that it's NOT granular like a simulated display using a bar graph. Any abrupt changes while tuning is an indication of instability and possibly oscillation. I look for those, which are difficult to see on a scope or computah display, but much easier on an analog meter. It also difficult to tune or adjust anything with a constantly changing digital display. A bar graph is better, but an analog meter is the best. Another common use is in high RF environments such as mountain tops, where amplified instrument front ends tend to rectify all the RF and produce erroneous measurements. The Simpson 260 will also rectify some RF, but after I added some ferrite beads and bypass caps inside, it's quite immune to RF. However, my most important reason is that I know how the meter responds to various common measurements and functions. I've been using a Simpson 260 since tube days. I can put the probes across a car battery or AC line and tell if all is well without reading the scales. After 50+ years of measuring the same things, I know where the pointer is suppose to stop. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On 6/19/2015 5:54 AM, John S wrote:
> I have many instruments. The most valued and cherished one is the Simpson 260. > I can easily do some things with it that is almost impossible with a DVM, > oscilloscope, etc. I hope I never have to do without it.
I have a fondness for pinball machines (and other arcade pieces) -- and have serviced them professionally and as a hobby for ~45+ years. I recall an "old-timer" I met on a job a long time ago. His "most valued" tool was a length of *wire* that he kept, wadded up, in his pocket. The insulation was old and cracked, ends were frayed, etc. It was amusing to watch me working with a pocket multimeter and him with that old piece of wire; each doing the same job with the same results but with vastly different "tools"! I've no idea how he made the transition to the "solid state" machines... As far as Simpsons... I rarely take my 260P out because its tucked away on the bottom shelf in my equipment closet. I've so many other DMM's lying around that *tend* to be more convenient (e.g., I have an 8840 sitting in the garage JUST for my routine car battery checks)
On Friday, June 19, 2015 at 6:20:09 AM UTC-7, George Herold wrote:
> On Friday, June 19, 2015 at 8:55:01 AM UTC-4, John S wrote:
...
> > Simpson 260. I can easily do some things with it that is almost > > impossible with a DVM, oscilloscope, etc. I hope I never have to do > > without it. > > OK What kind of things? I used a Simpson in the past. but now just > struggle along with my 'scope and DMM. :^)
The AC scale is duplicated in logarithm (dBm) units, so you can quickly determine gain or attenuation. Also, a small offset adjustment is possible using the meter zero adjust, which means you can line up the pointer at a reference tick, and watch for small deviations from the mark. Or, just apply a post-it with a pencil mark... When tweaking an adjustment for maximum or minimum, the moving needle is a lot more friendly than the DMM's little bargraph (and updates much faster than the DMM's digits). For extra credit: what impedance is implied by the dBm scaling? Why?
On Fri, 19 Jun 2015 11:24:21 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

>On Friday, June 19, 2015 at 6:20:09 AM UTC-7, George Herold wrote: >> On Friday, June 19, 2015 at 8:55:01 AM UTC-4, John S wrote: >... >> > Simpson 260. I can easily do some things with it that is almost >> > impossible with a DVM, oscilloscope, etc. I hope I never have to do >> > without it. >> >> OK What kind of things? I used a Simpson in the past. but now just >> struggle along with my 'scope and DMM. :^) > >The AC scale is duplicated in logarithm (dBm) units, so you can quickly >determine gain or attenuation. Also, a small offset adjustment is >possible using the meter zero adjust, which means you >can line up the pointer at a reference tick, and watch for small deviations >from the mark. Or, just apply a post-it with a pencil mark... > >When tweaking an adjustment for maximum or minimum, the moving >needle is a lot more friendly than the DMM's little bargraph (and updates >much faster than the DMM's digits). > >For extra credit: what impedance is implied by the dBm scaling? Why?
600 ohms, right? The telecom standard. -- Best regards, Spehro Pefhany Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8 Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48