What's on your test bench?
in [Design]
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From: John Larkin on 11 Nov 2009 22:59 On Wed, 11 Nov 2009 12:13:49 -0000, "Phil O. Sopher" <invalid(a)invalid.invalid> wrote: >Over a 40 year period of interest, I've gathered some >test equipment, AF Genny, RF Genny, Freq Counter, High >Impedance Voltmeter, Wheatstone Bridge, Oscilloscope. > >None of these is particularly small and all are at least a 6" cube. > >It seems to me that the same functionality could be achieved >these days with perhaps just a few inches of bench space, but, >would it be of any use? > >The eqpt I gathered together dates very much from the days of >designing circuitry with individual componenents (R, L, C, BJT) >and offers test and validation at that level, but nowadays we don't >work at that level (even op amps have been around for that 40 year >period). > >So, what do you have on your test bench these days, how big is it, >did you design it yourself, and what would you recommend to the >budding circuit designer of today who isn't in the industry and therefore >does not have access to Spice or Matlab to validate their designs? > > ftp://jjlarkin.lmi.net/DSC01371.JPG Parts cabinet to the left, whiteboard to the right. Out of sight is a bunch of cables and adapters and other small test gear, DVMs and RLC meters and such. Big stuff can be wheeled up on a cart as necessary. This is an Ikea "computer workstation" and parts cabinet. I do a lot of live-bug breadboarding on hacked copperclad FR4 and use the Bellin SMT adapters for wiring up small stuff. ftp://jjlarkin.lmi.net/BB_fast.JPG John
From: D from BC on 11 Nov 2009 23:29 On Wed, 11 Nov 2009 19:59:00 -0800, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Wed, 11 Nov 2009 12:13:49 -0000, "Phil O. Sopher" ><invalid(a)invalid.invalid> wrote: > >>Over a 40 year period of interest, I've gathered some >>test equipment, AF Genny, RF Genny, Freq Counter, High >>Impedance Voltmeter, Wheatstone Bridge, Oscilloscope. >> >>None of these is particularly small and all are at least a 6" cube. >> >>It seems to me that the same functionality could be achieved >>these days with perhaps just a few inches of bench space, but, >>would it be of any use? >> >>The eqpt I gathered together dates very much from the days of >>designing circuitry with individual componenents (R, L, C, BJT) >>and offers test and validation at that level, but nowadays we don't >>work at that level (even op amps have been around for that 40 year >>period). >> >>So, what do you have on your test bench these days, how big is it, >>did you design it yourself, and what would you recommend to the >>budding circuit designer of today who isn't in the industry and therefore >>does not have access to Spice or Matlab to validate their designs? >> >> > >ftp://jjlarkin.lmi.net/DSC01371.JPG > >Parts cabinet to the left, whiteboard to the right. Out of sight is a >bunch of cables and adapters and other small test gear, DVMs and RLC >meters and such. Big stuff can be wheeled up on a cart as necessary. > >This is an Ikea "computer workstation" and parts cabinet. > >I do a lot of live-bug breadboarding on hacked copperclad FR4 and use >the Bellin SMT adapters for wiring up small stuff. > >ftp://jjlarkin.lmi.net/BB_fast.JPG > >John White board? This is the era of BIG LCD displays and schematic software. :P Which brings me to.. No computer monitor on the bench??? I suppose it'll get accidently poked with the soldering pen.
From: krw on 11 Nov 2009 23:40 On Wed, 11 Nov 2009 12:13:49 -0000, "Phil O. Sopher" <invalid(a)invalid.invalid> wrote: >Over a 40 year period of interest, I've gathered some >test equipment, AF Genny, RF Genny, Freq Counter, High >Impedance Voltmeter, Wheatstone Bridge, Oscilloscope. > >None of these is particularly small and all are at least a 6" cube. > >It seems to me that the same functionality could be achieved >these days with perhaps just a few inches of bench space, but, >would it be of any use? > >The eqpt I gathered together dates very much from the days of >designing circuitry with individual componenents (R, L, C, BJT) >and offers test and validation at that level, but nowadays we don't >work at that level (even op amps have been around for that 40 year >period). > >So, what do you have on your test bench these days, how big is it, >did you design it yourself, and what would you recommend to the >budding circuit designer of today who isn't in the industry and therefore >does not have access to Spice or Matlab to validate their designs? At home? Nothing, if you don't count a couple of Fluke-77s and a couple of HF DVMs (left visible, used as bait). I don't do electronics at home. I get enough in the 55 hours/week or so at work.
From: JW on 12 Nov 2009 07:27 On Wed, 11 Nov 2009 09:53:13 -0800 "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote in Message id: <fSCKm.166325$Gs.21640(a)en-nntp-01.dc1.easynews.com>: >"JW" <none(a)dev.null> wrote in message >news:4mglf5losmns7t1s7uva8448t57d6bu1ui(a)4ax.com... >> Other than the decade box, all bought defective on Ebay and repaired by >> myself. > >I'd be interesting in hearing what sorts of problems they had, if you still >recall... The Lecroy 9374M scope had a problem with the battery back up circuit on the CPU board. Lecroy 93XX (and possibly other Lecroy) scopes are weird in that if the rechargeable battery falls below or above a certain voltage it locks up the CPU. In fact, if you disconnect the battery when it's up and running, the scope will freeze up. (Agilent 545XX scopes also lock up when the battery dies) This particular one's voltage would surge up to almost 5V on a power-up and stay there, possibly back-feeding or latch-up from the real time clock - I found that putting a 33uF tantalum on the Vbat voltage would prevent that momentary surge. The floppy drive was also bad, I figured out how to adapt a standard slim floppy drive used in laptops to replace the oddball Epson drive. The Keithley 2000 would fail random self tests - a power supply re-cap fixed it. I just fixed a Keithley 2001 MEM2 with the exact same issue, but that one's for sale now. I don't need that kind of accuracy, and it's missing some functions that the 2000 has. The HP 5385A counter had a shorted over-voltage protection zener in the 5V digital supply. The Agilent 6643 power supply had a busted LCD display. Rather than spend $85 for a new one from Agilent, I found that their 3488A switch unit shares the same display - they can be had for peanuts; nobody wants 'em it seems. After replacing the display the supply would error out in overvoltage mode when programmed to output a voltage greater than 2VDC, a bad op-amp in the sense inputs. The HP 8656B, can't recall that one... >mainly as an indication of, "when it's sold as busted on eBay, just >*how* busted does it tend to be?" More often than not, much of the stuff is quite repairable as long as someone hasn't already made a mess of it in a botched repair attempt. The only piece I bought and was never able to repair is a Tek 2430A which had bad CCDs - the chips are pretty much unobtanium these days. I'd say the most likely failures are: 1. Battery failures 2. Electrolytic cap failures 3. Shorted or open semiconductors in power supply circuits. 4. Oxidation of contacts. 5. Mechanical failures Working part time for one of the used test equipment companies has allowed be to gain quite a bit of experience and knowledge in certain "magic bullet" fixes. Those are fixes where a particular piece is notorious for certain failures and cures. I'm always on the lookout on Ebay for those.
From: John Larkin on 12 Nov 2009 09:59
On Wed, 11 Nov 2009 20:29:51 -0800, D from BC <myrealaddress(a)comic.com> wrote: >On Wed, 11 Nov 2009 19:59:00 -0800, John Larkin ><jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: > >>On Wed, 11 Nov 2009 12:13:49 -0000, "Phil O. Sopher" >><invalid(a)invalid.invalid> wrote: >> >>>Over a 40 year period of interest, I've gathered some >>>test equipment, AF Genny, RF Genny, Freq Counter, High >>>Impedance Voltmeter, Wheatstone Bridge, Oscilloscope. >>> >>>None of these is particularly small and all are at least a 6" cube. >>> >>>It seems to me that the same functionality could be achieved >>>these days with perhaps just a few inches of bench space, but, >>>would it be of any use? >>> >>>The eqpt I gathered together dates very much from the days of >>>designing circuitry with individual componenents (R, L, C, BJT) >>>and offers test and validation at that level, but nowadays we don't >>>work at that level (even op amps have been around for that 40 year >>>period). >>> >>>So, what do you have on your test bench these days, how big is it, >>>did you design it yourself, and what would you recommend to the >>>budding circuit designer of today who isn't in the industry and therefore >>>does not have access to Spice or Matlab to validate their designs? >>> >>> >> >>ftp://jjlarkin.lmi.net/DSC01371.JPG >> >>Parts cabinet to the left, whiteboard to the right. Out of sight is a >>bunch of cables and adapters and other small test gear, DVMs and RLC >>meters and such. Big stuff can be wheeled up on a cart as necessary. >> >>This is an Ikea "computer workstation" and parts cabinet. >> >>I do a lot of live-bug breadboarding on hacked copperclad FR4 and use >>the Bellin SMT adapters for wiring up small stuff. >> >>ftp://jjlarkin.lmi.net/BB_fast.JPG >> >>John > >White board? >This is the era of BIG LCD displays and schematic software. :P I scribble the schematic of a breadboard and correct it as I go, and list measurements or notes on the whiteboard, then photograph everything... the breadboard, scope waveforms, the whiteboard. If any of it is interesting enough, we release it to an engineering notes folder on a server, or dump relevant bits into our parts database. Some of the whiteboard pics and scope shots go directly into customer proposals. They seem to enjoy it, a break from PowerPoint. >Which brings me to.. >No computer monitor on the bench??? I'll add a laptop if I'm talking to a serial box or background debugging firmware or things like that. >I suppose it'll get accidently poked with the soldering pen. I don't have a lot of room - this is in the corner of my office - so I bring in equipment as needed. The big sampling scope weighs about 80 pounds, and the Mantis is bolted down, so they're permanent. John |