Equipting a test bench

Something like this:

ftp://jjlarkin.lmi.net/DSC01371.JPG

John

A deep memory (1M or more) digital oscilloscope. The Rigol DS1052E is sufficient. Deep memory is essential for digital and analog debug work.

An old analog oscilloscope, 100MHz+ bandwidth. Pretty cheap and might come in handy.

Two soldering irons for SMD work, and SMD concave tips too.

A x4 or x6 magnifying lamp for SMD work.

A PC based digital logic analyser. Combined LA's in digital oscilloscopes can be handy, but USB ones offer better bang-per-buck.

Two good quality digital multimeters, preferably one with 4.5digit and

Speaking of USB logic analysers, anyone tried one of these?

Speaking of USB logic analysers, anyone tried one of these?

Eight channels can be enough for lots of uses. I used to have an Ant8 (RockyLogic, no longer sold retail) as my "carry around" USB logic analyzer; thought it was great.

A couple of points about the Saleae analyzer:

1. Input voltage range is -0.5 to 5.25V. The trigger is fixed at -0.5 to

0.8V (low) and 2 to 5.25V (high). That's great if you're looking only at traditional TTL logic levels. Not so good if you need to look at something as exotic as RS232. That fixed trigger could also be a problem with 3.3V and below CMOS gates, as well.

1. It looks like the timestamps and the "200M+ samples, absolute limit depends on system ram" are applied on the PC side, not the device side. It communicates over a packetized bus (USB), therefore the timestamps can be affected by other traffic on the USB. If there are, say, a USB serial port and USB JTAG or ISP also on the bus, then accurate time stamping will be ... problematic. Trying to figure out how much jitter there is with an interrupt service routine? Good luck.

USB logic analyzers can have a lot of bang for the buck (and I use mine nearly every day). They tend to fall into two general classes: deep sample memory or shallow + compressed sample memory. The deep memory devices (typically around 1 Mbit per channel) force a tradeoff between precision and total capture time. Sampling with a 0.1 usec precision can't run for longer than 0.1 seconds. Is that a problem? Could be in some scenarios.

The compressed sampling devices tend to run a few Kbits per channel. They do allow for long delays between events at quite high precision. However, they can also be quickly exhausted if one of the channels has a lot of high speed transitions. Getting long and precise captures of neighboring signals would probably require dropping the very active channel.

So, look at the front end and consider if it is wide enough and flexible enough. For my own use, I needed one that could handle down to -15V and trigger at -6V (for NTDS "A", not common but if ya need it ya need it), as well as being able to tweak the trigger setting for more ordinary stuff like CAN bus signals. Even just for RS232, to get outside of the "gray zone" needs a trigger outside of +/- 3V and needs to handle inputs that could reach as far as +/- 15V.

On the sample side, I would run away, fast, from any one that added the timestamps on the PC side of a USB connection. On the deep versus compressed memory, I personally go with compressed for the flexibility.

--
Rich Webb     Norfolk, VA

Make sure it has A and B sweep!

The samplerate is way too low. I have been debugging some SPI DAC problems with the Intronix USB logic analyzer from Pctestinstruments but I still don't like the UI. I recently picked up a TLA704 from Ebay, fitted it with a 800x600 screen and more memory. Still waiting for the 136 channel 4M acq. module to arrive. If things get messy nothing beats the real deal...

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
                     "If it doesn\'t fit, use a bigger hammer!"
--------------------------------------------------------------

My scopes have one screen of memory, which seems to be enough.

Why? A 100 MHz digital scope works fine.

Metcal!

Mantis!

I've never used a logic analyzer. A digital scope can spot the obvious glitch-type errors, and all a LA does after that is force you to do the thinking you should have done in the first place. They take so much time to connect and use, it's a lot quicker and easier to just think.

The fungen+scope IS an ESR meter. And a lot more. But personally, I very rarely need to measure ESR.

I'd vote for an AADE LC meter instead.

And good lighting. And a enormous power strip or three.

And a whiteboard on the wall within easy reach.

John

Sometimes the danged datasheets need interpreting, though. Running up an I2C channel on a new processor family that needs to chat with another never-used slave device and "Did I understand all the registers and results on both ends of this correctly?" It's awfully handy to be able to connect onto SDA and SCL, and then tell the analyzer that those two are an I2C channel.

And a stool for the cat(s) so they have a place to nap instead of on the workbench!

--
Rich Webb     Norfolk, VA

And everyone, absolutely, needs one of these. Or three, to be safe:

John

Yep, almost as necessary as the beer fridge. ;)

(Your model is a great deal better than the old SRS one I used to have, which had 5 ps settability and 200 ps jitter. And people think that only delta-sigmas have that kind of specsmanship.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

We get down around 5 ps RMS jitter for short delays. The SRS clock-quantization-compensation technique is inherently tricky for both jitter and insertion delay. A couple of ramps have to be perfectly linear and perfectly matched, and that's hard to hold long-term. We just start a burst oscillator at trigger time and work off that.

But seriously, everybody should have a pulse generator of some sort, an old HP or Philips... something with a rate generator, pretrigger out, delay, and width. Great for pulsing fet gates and relays and logic and such.

John

Hmm, the interface is a bit 80-ish. Where is the touchscreen? All the stuff I designed lately that needs controls or user input has a GUI with a touchscreen (and optionally support for different languages which some customers manage to tweak to Chinese as well). Image not having to drill all those holes and do without a PCB that holds buttons? And I bet an LCD with touchscreen is cheaper than the VFD. Think about it :-)

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
                     "If it doesn\'t fit, use a bigger hammer!"
--------------------------------------------------------------

[snip]

Won't do any good, if I don't give my cat proper attention, he ignores the "stool" and plants himself firmly on top of my papers...

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | Coming soon to the elementary school in your neighborhood...

I pledge allegiance to Dear Leader Barack Hussein Obama and to the community organization for which he stands: one nation under ACORN, unchallengeable, with wealth redistribution and climate change for all.

That stool looks at least 10 years old... I wonder why people keep buying those for their cats. It must be a message to visitors saying 'look I spend money on my cat' :-)

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
                     "If it doesn\'t fit, use a bigger hammer!"
--------------------------------------------------------------

He's a carbon copy of Thunder (my well named cat)!

My cat sleeps in it... when I'm not at my desk. The shutters are usually open, I closed them to take the photo. The cat likes to sit up there and look out the window... until I sit down, then he moves to park on my desk ;-) ...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
Coming soon to the elementary school in your neighborhood...

I pledge allegiance to Dear Leader Barack Hussein Obama and to the
community organization for which he stands: one nation under 
ACORN, unchallengeable, with wealth redistribution and climate
change for all.

We did. This is really easy to drive, especially when you want to look at a scope screen and dial in the proper timing with the spinner knob, by feel, without looking at the DDG. If we're 80's, the SRS unit is

70's.

Small touch screens are a real PITA.

Of course an LCD is cheaper than a VFD. The VF looks much better.

John

I am surprised that you even achieve one single functional circuit on that "bench". The work "pad" is an insulator, a HUGE ESD no-no. Do your customers know that you take ZERO ESD precautions?

For the OP, the word "equipting" is NOT a word at all.

Scope memory is usually declared as a function of sample counts.