building a hobby-lab

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Gents:

First post.

I'm populating a home hobby-lab to support some amusing experiments in 2-
photon light-scattering vis Levinthals Paradox. Previous attempts proved  
unsuccessful. I'm improving test equip all-around. First item is a  
digital Oscilloscope ( replacing a data-logger ) : I'm looking at the  
Siglent SDS100-series: 4-channel 200-Mhz bandwidth. Will be used to  
trouble-shoot photo-transistor based detection circuits.  Price ~ $700.  
I've always used HP/Tektronics or Fluke, but now retired I'm priced out  
of the grant-money market. Of-course the Goldilocks freq is 10^15 Hz, but  
you have to pray for sub-harmonics vis protein folding.  Anyrate what do  
you think about the OScope choice ?    

Re: building a hobby-lab
On 04/11/18 01:33, will wrote:
Quoted text here. Click to load it

I'm a boat anchor fan myself.  Check out eBay for scopes.  I've bought  
eleven of them there, and have had zero duds.  Something in a nice Tek  
TDS 544A (500 MHz, 1Gs/s) can be had for under 5 bills.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: building a hobby-lab
On Thu, 12 Apr 2018 10:55:56 -0400, Phil Hobbs wrote:

Quoted text here. Click to load it

PH:

Appreciate your comments.  Having used HP/Tektronics/Fluke for 50-years  
I'd love a classic-form OScope. However ... I profoundly distrust eBAY  
merchants ( very sharpsters ) and eBAY payment methods. You are prolly a  
much quicker business-man than I am. I prefer to deal direct with  
manufactures ( my coffee mugs come right from the Vermont potters-wheel  
and my light-scattering-cuvettes direct from a small Chinese silicon  
foundry).  

The $200 difference between shyster-Bosco on eBAY and  warranted grant-
polished paid-delivery + support Siglent is small beans. Too bad Siglent  
does not sell a well-priced sine/squ/ramp 25 MHtz function generator and  
indeed eBAY products never include the cables. Kinda like selling a  
kitchen  table with no legs, but that's eBAY style.      

Re: building a hobby-lab
snipped-for-privacy@butchersboulevard.commypanprofile says...
Quoted text here. Click to load it

If you pick the sellers that have 50 or more transactions and near 100%  
feedback you are probably ok.  I understand ebay stands behind them also  
so you canget a refund.

I have bought sevreal used things off ebay for close to $ 1000 and a  
service monitor for $ 1700.  All wree as advertised or better.

China has some new function generators on ebay for less than $ 100 that  
do well up to about 5 MHz with square waves and 25 with sine waves.  I  
bought one and there is a modification that costs about $ 20 or less in  
parts from Mouser or Digikey that makes it work even better.



Re: building a hobby-lab
On 04/12/18 11:56, will wrote:
Quoted text here. Click to load it

That's not my experience at all, but it's your money.

Cheers

Phil Hobbs

--  
Dr Philip C D Hobbs
Principal Consultant
We've slightly trimmed the long signature. Click to see the full one.
Re: building a hobby-lab
On Thu, 12 Apr 2018 15:56:02 -0000 (UTC), will

Quoted text here. Click to load it

Most of my now antique lab equipment was purchased on eBay:
<http://www.learnbydestroying.com/jeffl/pics/home/slides/lab.html>
There's plenty more stored in various corners.  I tend to buy low cost
"for parts" equipment, and fix them myself.  If I really want to buy
something to repair, I buy three of them:
<http://www.learnbydestroying.com/jeffl/pics/home/slides/BL-shop5.html>
That's one of the benefits of buying HP, TEK, and other name brand
equipment.  If you need schematics, manuals, and parts 40 years later,
you can find them.  For example, the HP 8640B signal generator is
known for having the output RF power amp get blown up.  40 years
later, you can get replacement pullout:
<https://www.ebay.com/itm/362098534959
<https://www.ebay.com/itm/232157976158
I could probably build a complete generator from scrap parts found on
eBay.  I doubt if you could find repair parts for a Siglent scope even
today.  I just downloaded the "service manual" on the Siglent SDS2000X
scope.  
<https://www.siglentamerica.com/wp-content/uploads/dlm_uploads/2017/10/SDS2000X_ServiceManual_SM0102X-E02A-1.pdf
No schematics, no parts list, some adjustments, and an assembly
drawing showing only the test points.



--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: building a hobby-lab
On Sat, 14 Apr 2018 16:45:02 -0700, Jeff Liebermann wrote:

Quoted text here. Click to load it
SDS2000X_ServiceManual_SM0102X-E02A-1.pdf>
Quoted text here. Click to load it

JL:

You make solid points about the importance of quality test equipment.  
I've prolly argued the same way to my EE lab students. Yet now, retired,  
totally unsupported with time and opportunity to attack a single amusing  
experimental task I find efficiency-of-tools the prime virtue.  

A  ( plug-N-play ) $700 Siglent Oscope that helps me build photon  
detectors, and then serves as part of the detecting system provides  
enormous value. I can focus on component design & experimental issues
knowing I'll drop dead before my Oscope needs repair.  

I would not have thought that way 20 years ago, but I think that way  
now.      

Site Timeline