Hi,

I’m trying to build a “test bed” that will help me learn more about electricity by doing some projects and experiments.

My idea is to assemble a few pieces of test equipment that will give me quantitative (measureable) feedback about things like volts, amps, ohms, watts, frequency, etc.

So far I have a Tektronix 100MHz oscilloscope, a 20Hz Sweep/Function Generator, a multimeter, and an clamp meter with an AC line splitter (to measure in-line current).

I started with the oscilloscope and have pretty much figured it out, although I’m sure there are many uses I haven’t discovered.

While I understand digital technology (computers and networks) and the basics/concepts of electricity I’d like to be able see in real-time the relationship between the components of Ohm’s Law (including volts, amps, ohms, and watts).

To be square, I’m kind of into gadgets and I especially like meters, readouts, displays, etc. I like seeing measured results and I enjoy learning by hypothesizing and doing, as well as by reading and discussing.

So, I’m thinking about adding a DC Linear Programmable DC Programmable Power Supply (maybe a BK 1786B) and a DC Electronic Load (maybe a BK 8500). I’m also thinking about adding small stepper motor and a DC stepper motor controller to do some experimenting/learning. With these devices I’d like to observe the changing relationships between volts and amps, etc.

The motor and motor controller aren’t too expensive but before I go all-in for a linear power supply and an electronic load I thought I’d check with people here who have more training and experience to see if I am headed in a reasonable direction. My goal is to learn by doing, hopefully in a safe and practical manner.

Any thoughts/advice/questions appreciated.

Thanks! EF

 

Watch this to start

 

I don't know where you are located, but I'd recommend getting something like this kit, sold by Radio Shack:

http://www.radioshack.com/product/index.jsp?productId=3814337&retainProdsInSession=1

 

Hi davebee,

Thanks - that's a pretty/very interesting recommendation. Turns out that I purchased that exact kit several years ago and a couple days ago decided to get it out of the box and start working my way through the lessons (it had just been sitting all this time). I've but in several hours on it and it has been pretty fun and rewarding - I've learned a few things and it is a very good kit for introducing how digital technology runs on top of fundamental electricity/analog circuits but I'm thinking there might be something more "volts law" oriented. Any way, you're recommendation was nearly a mind-reader. Thanks again. EF

 

Watch this to start

Thanks - informative and entertaining!

 

Another question:

(I know the answer is probably "it depends on what you are trying to do" but since this is all experimental it is hard to say)

Which might be more useful, a DC power supply that supports 30V and 3A or a DC power supply that supports 18V and 5A? Any thoughts/reasoning on what would be more versatile? (Or would a ~30% more expensive 30V 5A unit for some reason be significantly more versatile?)

Thanks

 

Well, "it depends on what you are trying to do." I personally do mainly low powered circuits so I'd be very happy with a 3 amp output for breadboarding and experimentation; if I need more power for a specific application, I will build a power source specifically for that circuit (or raid one from other equipment ). I do think that having a split supply is terribly useful in particular if you plan on doing any work with op amps or amplifiers so I'd consider that. +/- 15 V is very useful for most circuits. More is better, of course, if your supply is efficient.

Other than that, I'd buy a bunch of assortments of resistors and capacitors, transistors, diodes, etc., and buy some of those plastic fishing boxes or bead boxes to sort out the components. But, again, "it depends on what you are trying to do." (And how much you want to spend ).

 

Yeah, what he said.
99% of the time, I am just checking a theory by building a circuit that uses only a few milliamps. After I verify the small building blocks of the design, I add up the current for all the circuits and build a power supply (or choose the batteries) for the finished project.

For me, a +/- 15V supply that can do 100 ma would be more than enough, most of the time, in fact, when I designed a supply for my workbench, I did exactly that! I used 317LZ chips that self limit at about 100 ma so there would be less smoke when I messed up.

 

Thanks for the advice - I appreciate it.

Another question: for just basically learning the relationships between the components of Ohm's Law do you have any preferences for a DC linear power supply vs. a DC switching power supply? Thanks

 

...
Which might be more useful, a DC power supply that supports 30V and 3A or a DC power supply that supports 18V and 5A? Any thoughts/reasoning on what would be more versatile?
...

BOTH! Seriously, you cannot have too many DC power supplies. For now I suggest you build some simple cheap variable supplies like LM317 supplies which will do 1.25-30v at about 1.5A. Always make sure a supply has both a voltmeter and ammeter, I really prefer analogue moving needle type ammeters, voltmeter is not so critical and could be digital or analogue.

Also variable current limiting is very useful, you can do this with a second LM317 as a current regulator before the voltage regulator LM317.

If you are going to work with 5v digital then you can use a 7805 regulator for 5v, then a LM317 before it to set a current limit. I have one of these and it is mega-useful, with a 3 position switch to set current limits 20mA/50mA/100mA.