Hmmmm.... The Digilent Lab in a Box has dual channel 14-bit 105 MSPS ADC and can do 2 x 5 MHz inputs. Labview's MyDAQ which I have does dual 12-bit 200KSPS inputs, and is not much use above 20 KHz.
Rats...I've been had!! Would much rather have the LIAB.
Note to self - check if Digilent have an outlet in Aussie....
Simulation is like a short skirt: it's supposed to looks attractive while covering up essential parts.
Having said that, there's always a reason for a difference between the simulation and bench measurement. If it's important, it can be found and accounted for in the simulation. The trick is that such fixes often require being familiar with, ahem, the internal features of the simulation environment.
As Rodney Brooks once said about robot simulators, "Simulations are doomed to success." You can do things in simulations that appear to work very nicely but would not work in the real world. The difference is all the parameters and limitations NOT included in the computer models. This is an old problem.
Bob Pease of National had lots of fun showing that the real world and the SPICE simulation of it were often different. Some designs that worked well on the bench for explainable reasons could not be accurately simulated in SPICE, and vice-versa. The argument is that you have to know what the simulation is doing.
IMO, a big piece of this is learning the "knowledge in the hands" that comes from working with real components in the real world. This knowledge is essential for good designs. If you have this knowledge, SPICE can be valuable for you to increase the precision of your design.
Hands-on knowledge will also let you know when the SPICE is not working, as in it has done the equivalent of taking the square root of your social security number: simultaneously precise and meaningless.
Excellent idea, but can't we get the same affect by using pspice or a cheaper (student) version of many analog simulation programs. There are even how-to books to go along with them. A few years ago, on ebay, I bought an electronic trainer consisting of several pegboard-like hook up slabs with .1" spacing, fixed and variable power supplies, and a waveform generator, all packaged into a neat carrying case. I am not sure who made those, but they should bring them back. So a student could create a circuit using the computer simulator, then actually build it to see how it performs in real life. No million dollar labs reqd. I still do that when my circuit is in a concept stage, before going to prototype.
This is a great idea! Gone are the days when Saturday morning was tied up in a lab (because that was the only time slots open). I can think of a better way to get students engaged then hands on work with the real thing. With the low cost this should be a major help for students and could possibly be in every intro to engineering course.
I am doing a course at the moment and as a consequence of that I managed to get my hands on a student version of Labview with their MyDaq module - $199 the lot. It has 2 analogue inputs and 2 outputs and 12 Digital I/O, and a multimeter. Apart from the Labview software which allows you to program and design custom "Virtual Instruments", it comes with a suite of ready-made ones, including a DMM, scope, function generator, AWG, bode analyser, spectrum analyser.... The one limitation I've found annoying is that the ADC/DAC are 200 KSPS and the associated instruments only go up to 20KHz. But for most basic student work this is not toooo big a deal. I'd be interested to see how Digilent's offerings compare with this. Anyone used both?
Hats off to ADI and Digilent for doing this. Students really benefit from the hands-on learning that can only come from playing with real components, and it does seem that universities have been "virtualizing" lab course work for quite some time now.
Back when I was a student teaching assistant we still had real lab courses with a parts stockroom and lab equipment. I always got a chuckle out of seeing otherwise brilliant students scratch their heads in dismay when they built a circuit and found that the measured voltages & currents were not precisely what their calculations predicted -- or when things changed as components heated up. You can lecture a student about parameter tolerances and temperature coefficients, but nothing beats building a circuit and experiencing those effects first-hand.
Another humorous memory from those days: a two-stage bipolar transistor amplifier design project with feedback. Nearly every student would ask "what value should I use for the beta of these transistors? The data sheet says minimum 60, maximum 300." And of course I would tell them to make sure the amplifier meets all specs for beta = 60 all the way to beta = 300.
The ensuing look of terror on their faces was priceless!
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