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500-in-1 Electronics Kits?
Oneamp asks: "I'm interested in a '500-in-one' type electronics kit. Amazon lists a few, but I've seen some user reviews that maybe they are not all they're cracked up to be. Most of the complaints seem to be of the 'Manual sucks' variety. Nevertheless, I'm sold on the idea. Can any of you, who have had actual experience with any of these kits, recommend a good one?"
Surely the manual won't explain the electronics behind it... but if you want to have fun building stuff, then go ahead a try it.
;)
I had a few of these as a kid, and they were almost certainly not disappointing... It makes me want to buy one right now!
Ditto
To be honest, I think your best bet is to get the kit and the "manual" separately.
A few years ago I had the opportunity to tutor an absolutely prodigal young kid, who happened to be 'into' electricity that season. I couldn't find any electricial kits that seemed up to snuff in both the hardware and manuals departments, so instead I ended up taking one of the bigger Radioshack kits, and then using some of the Forrest M. Mims III books as project guides. Why they don't have that guy do the manuals for the kits I have no idea, because he's really quite good.
For the few projects we wanted to do where the board didn't have the right parts, I just hacked them on, either in place of parts that I thought were trivial (resistors, etc.), or just by drilling a new hole in the board surface and adding it in.
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I remember playing with these in the early 80s. I think I had a 150 in one, and then they came out with the 160 and 500, but it has been so long I don't remember for sure. There were no ICs, just bunches of resistors, capacitors, etc., all with wire jumpers that were held in place by springs. Seems like there were all kinds of circuits you could build, from water and light sensors, to a radio.
I don't know if they are "worth it" as far as parts are concerned, but if a kid is wanting to play with and learn about basic electricity and electronics, it can be a good toy. In my case, my father worked on electronics and I grew up calculating resistor values by color and reading schematics.
Kits like these might be a good way to gauge the interest of a young person in electronics. If they really enjoy the kit, then it's probably going to be worthwhile to invest in more serious projects, books, and so on.
It used to be you could buy all kinds of chips and components from radio shack to build your own stuff. Over time a lot of those have fallen by the wayside. It's still possible to get some of them, but not like it used to be. Instead, I find Fry's Electronics to have all kinds of kits and things to build, like Radio Shack used it.
. 62,400 repetitions make one truth -- Brave New World, Aldous Huxley
Weird this question should come up. I'm just sort of starting to learn about how electronics work, and picked up this thing at Fry's for $12.99. It's for kids, and I'm in my 30s. But what the hell.
It comes with a 76 page illustrated book that takes you through building circuits of greater and greater complexity. I'm only up to page 22 or so (capacitors). The illustrated book is fairly clear, uses a water/pipe analogy to explain what's happening..
This, along with this free book, has provided hours of fun and an interesting intro to how these electric devices we see all the time actually work...
I haven't used a 500-in-1 kit yet, but considering how cheap this was, I feel like I've already gotten my moneys worth in watching a capacitor charge at different rates depending on the resistance I throw in front/behind it.
I know, I know. I'm easily entertained. Can't wait to make the transistor radio. That'll be cool. I mean, when it's done... I'll know how a radio works!
For anyone who's ever been interested in electronic machines and how they operate, I highly recommend the book ("Lessons In Electronic Circuits"), which is easy to read, and getting one of these little kits. Good times.
When I was younger I had this 200-in-1 kit which I am amazed to see is still being made! The manual for this one was good, at least in the edition I had. It included circuit diagrams for everything along with some explanation. Early circuits included wiring instructions - later on, you were supposed to figure those out from the circuit diagram. The projects start simple: by the end, you're using almost all the components on the board.
I see that the same company makes a 500-in-1 kit. Assuming this is of the same quality, it would be worth considering.
The problem with the 200-in-1 kit is probably common to all such kits. The transistors, ICs and LEDs are real - they are easy to damage by incorrect connection. You can replace the transistors with a bit of effort, but some components are soldered directly to a board. It's a real pain if you damage anything. I also don't like the use of batteries as a power source. I suppose that's a safety thing, but I'd prefer a good quality low-voltage PSU with an electronic fuse.
I think the next step after a kit like this is making your own circuits from 74-series logic ICs, which provide basic logic functions and some more complex devices like flip-flops, registers and counters. You can make all sorts of fun stuff with this, and you really only need a data book that covers the 74 series, a breadboard and a 5 volt PSU. This is great fun. Especially when you add a microcontroller!
>north
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An op-amp is basically two transistors with the emitters joined together and connected to ground through a large resistance (ideally, a constant-current sink; but bear with me for now). The collectors are connected to supply via load resistors, and one of them is labelled as the output. (The other collector can be used as an inverted output, for connection of another stage to give more gain.) The two bases, with series resistors, are the inputs; the non-inverting input is the base of the transistor not serving the output.
When a voltage is presented at the inverting input, a current flows into it; the transistor on that side tries to let a larger current through its collector (and thus its emitter). The voltage at its emitter -- the output -- goes down. When a voltage is presented at the non-inverting input, a current flows into the base of the transistor on that side and it tries to let a larger current through. But the shared emitter resistor means that the other transistor can't let so much current through anymore, so the voltage at its collector goes up.
The reason for using a constant-current sink in the emitter path is that the changing collector-emitter resistances of the transistors can be significant, making the transfer function horribly non-linear unless the device is only working over a very narrow voltage range (much less than the supply voltage). This was never a problem with valves, when the circuit was called a "long-tailed pair" in reference to the large resistance between the two common cathodes and ground. Fortunately, constant-current sources and sinks are not hard to build using transistors, as long as you can find a pair which have similar electrical properties (obviously) and are in good thermal contact (so temperature variations affect both equally). Such conditions are easily met in an IC.
Get this one: http://www.radioshack.com/product/index.jsp?produc tId=2102913
It has a VERY good "manual". Actually, there are two - one focused on digital, one on analog. This is the kit that started me on a long journey from "I don't know what a resistor is" to taking graduate classes in electrical engineering.
You will also want to get Horowitz and Hill's "The Art of Electronics". If you have any interest at all in learning about circuits, you'll want that book.
Yes. And it's not really a short circuit, because no current flows through it.
The reason why the input voltage difference is nearly zero when negative feedback is applied, is because the amplifier is operating linearly. So actually, the difference between the two input voltages is the output voltage, divided by the open-loop gain. But the open-loop gain is huge, so the input voltage difference will be tiny.
Now, there's a thought. If you applied the same inputs to a second op-amp on the same chip (so, hopefully, having the same open-loop gain), would you get a sane voltage at the output, even with no negative feedback?
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