Working with Modest Equipment

RE: Working with Modest Equipment

DAB — Sat, 06 Feb 2016 20:23:54 GMT

It is not the instruments that make accuracy, it is the attention to detail during your experiments.

They teach error analysis for a reason. It allows you to assess your results within the limits of your instrumentation.

This problem is why Heisenberg failed to come to the correct answer about the electron cloud around atoms. His data told him that the charges within the cloud were quite small and uniform, but he incorrectly concluded that he could not find the electron because his measurement instrumentation affected the electron position.

My own analysis of his experiment provided me with a different conclusion which is more consistent with other observations about the electron cloud and clarifies the relationship between the atom nucleus and the electron cloud.

DAB

RE: Working with Modest Equipment

Workshopshed — Sat, 06 Feb 2016 13:20:33 GMT

Great points, I could not find a like or helpful button for the main post although they are there for the comments.

RE: Working with Modest Equipment

shabaz — Sat, 06 Feb 2016 10:04:36 GMT

I also like that most of us have very sensitive or very high performance equipment for helping with our projects, yet some people don't realise it!

For example a radio makes an incredible test tool, possibly one of the most sensitive bits of kit and we all have it. And the cheap SDR dongles too.

The PC sound card and powerful free software allows for audio related projects.

And like Don mentions we can use high performing op-amps easily. Dev-boards are cheap, so pulling up signals and then processing them with (say) a PC is possible.

I needed a test signal, and I'm using a frequency synthesizer dev-board from TI for it, saving 4 figure expenditure on new gear and providing a signal better than the ancient test gear from ebay that might sell for $1000+. Basically individuals can now do more.

There was a time where if a microcontroller was needed inside a project then it also needed expensive equipment to program it in, and

equipment to test the code. Now none of this is needed, there are cheap dev-boards for that too (and no need to even build and test the

microcontroller portion of the project if an off-the-shelf board is used for the prototype). The bedroom lab is a real option, no need for stacks of test equipment on shelves to get a lot done. Also, there are simulation tools so testing can be virtual too. I love that many manufacturers have online tools to create circuits based on specifications, like TI has on their front page. More chance to get it right first time.

The low-cost logic analyzers like OBLS will handle logic signals up to 100MHz I think from memory (provided there is no issue with the signals! - it is no substitute for a scope).

Also the BeagleBone Black (or other SBCs) can sample and generate signals at 100MHz, supporting close to a Gbps of sustained capture too. I managed about 14Msps of 8-bit ADC capture with little effort (so more than enough to trigger on and capture 1MHz analogue signals), and there is a project by someone that managed 100Msps for use as a logic analyzer.

RE: Working with Modest Equipment

D_Hersey — Sat, 06 Feb 2016 05:06:30 GMT

There is a distinction to be drawn between precision and accuracy. The DVM did not completely supplant the analog meter, for example. In critical safety situations, glancing at a needle has been found to lead to a quicker human response than interpreting digits, not to mention the risk of sliding a decimal point. The needle implies quantity. Finite sums can be scaled to 0-1 or -1 to 1. Unipolar and bipolar meters (I don't have to remind John of this) existed.

MIG fighters used IN-9 and IN-13 displays for fuel gauges. Quickest comprehension was afforded by these devices.

I still recommend op-amp circuits to the reality-based community.

RE: Working with Modest Equipment

jw0752 — Sat, 06 Feb 2016 02:49:23 GMT

Hi Jan,

I totally agree with your approach. When I started into electronics marginal equipment was all I could afford. I was a technician involved in repairing the equipment that was designed by others. Once I got used to working with $20 analog meters and Radio Shack test equipment I stayed with it. It is easy to fool oneself into thinking that the better equipment will make a difference in the quality of the work but most of the time the difference comes back to thinking about the problem to solve it. I bought better equipment a couple times but ultimately found myself making most of my tests with my old analog meter. Obviously I got along well with my cheap meters because the complexity and precision of the equipment I was repairing really didn't demand Keithley Precision. That being said I do really appreciate it when there is a proper tool for the job at hand. There is nothing worse than trying to remove phillips head screws with a flat screw driver. A good example is the little de-soldering iron you recommended to me a while ago. That machine works extremely well and makes me wish I had purchased one years ago. The only plus, to not having one sooner, is now I know all the hard ways to salvage a circuit board.

John

RE: Working with Modest Equipment

D_Hersey — Sat, 06 Feb 2016 01:19:21 GMT

The trick to making circuits work with low test equipment is to make them self-policing. Use feedback and sensors to see that requests were faithfully honored.