tcepsa: (I'll fix it!)
I spent far more time than may have been prudent playing with electronics last night.

I now have a square wave generator in the form of an astable 555 timer circuit (I've wanted one of those for years!) If I remember right, I could also use that in combination with the proper op-amp arrangement to make a triangle-wave generator (square wave + integrator = triangle wave).

This is, however, merely the means to a larger end. I then went on to try to get that to drive a resonant LC circuit. This consumed the majority of the time, and while I am not sure I have come out all that much wiser for the experience, I think I finally got to the point where I understand enough about what it's doing to actually attempt to create a receiver for it. Yes my friends, I have taken up my electronic lance and am heading full tilt at the windmills of wireless power transfer.

The irony of all of this is that it, in turn, is merely a cog in my greater scheme for an advanced human-computer interface device, which would be much more convenient if it were entirely wireless and did not need a battery (or could run off rechargeable battery and run or charge off of wireless power).

I was actually inspired to look into this by [livejournal.com profile] adularia's ongoing project, as I am hoping to do an implementation of that concept, but wireless and probably with a different sensing mechanism.

It was a good night ^_^

Cut for tangent about time management skills )
tcepsa: (Computation Suspended)
I am primarily writing this for my own edification. If you find it useful as well, so much the better ^_^

I have either been missing or unable to retain a rather important piece of knowledge pertaining to the usage of electrical measurement tools. If you've ever looked at a digial multimeter, for instance, you've probably noticed that around the dial the settings are marked in units like "2 V" "20 V" etc. I could never figure out why they were marked with a leading two; my brain kept trying to go "Okay, it reads .50, but we're on the 20 V measurement so that actually means that the value being measured is 10 Volts."

This is Very Much Not True.

The value is actually .50 V; the only thing to actually look at is the units on the display and the main number being displayed. The 20 is a reminder that 20 is the upper limit for that scale (actually 19.99). This is because the display is a "3.5 digit" display, meaning that it has 3 full LCD digits and the leftmost one can only display a 1 or be off completely. To help compensate, they shift the decimal point around (which is why you should not pay attention to the fact that it says "20"). When the scale is set to 20 V, the decimal point will be in the middle. The leftmost two digits can go up to 19, and the rightmost can go up to 99, giving you a total of 19.99 V, just under the maximum of 20. (Think of it as a mathematical "open" upper bound).
tcepsa: (TryScience!)
Last Wednesday I ended up making a trip up to Baynesville Electronics in Towson (northern edge of Baltimore). It was awesome ^_^ I'm not sure quite yet whether I'll be going back there for parts often, but it seems fairly likely. On the one hand it seems like online sites are quite a bit cheaper, but on the other hand I have not actually verified that and I really like the idea of supporting these guys, as there are, in my opinion, not nearly enough stores like that around. A (more-or-less) local alternative to Radio Shack? Sign me up! Plus the ability to just run out and get a part in under and hour vs. placing the order online and waiting for it to be delivered... sure there's the extra element of anticipation in the latter case, but even I can only take so much suspense ~grin~. And projects are more likely to end up shelved because I lost momentum while waiting for the part to arrive than if I make a run to a store (an hour of downtime could still be too much of a drag on my mental flywheel, but it's still significantly less than that of ordering a part and waiting for it to come in). That having been said, I am on the edge of my seat waiting for my Boarduino kit from Adafruit to arrive. Mmmmm, antici... pation!

So, enough philosophical rambling, back to the foray! While I didn't interact much with the staff, they seemed both knowledgeable and friendly in a way that gave me a sense that they were there because they liked being there. I spent most of the time I was there (probably about an hour-ish, maybe a little longer) just wandering up and down the rows of shelves looking at all of the different things they have stocked. While I saw a lot of neat stuff that I'd love to play with at some point, a lot of it also left me with a vague feeling of, "Huh, that thing has an interesting shape, I wonder what it does but I'm not going to make too much effort to find out right now. Maybe someday I'll know, but if not that's probably okay too." Normally I'm used to going into a place like that and needing a lot of willpower to counteract the "Oh my god it's so shiny I want it all right now!" but I think that's been happening less lately; "It looks nifty but I don't have time for it," apparently quashes that gleeful urge to buy a whole bunch of stuff really effectively.

I'm not certain I like that. In fact I'm kind of thinking I don't. "OOOO I'm going to buy all of this right now!" is not good for the wallet, but "I won't ever have time for any of this..." is, I suspect, not good for the soul. More to poke at later...

And I did buy some things, for projects that I am currently working on. If anything, I'm seeing a positive swing back in the direction of getting excited about and engaged in projects like this; I am actually actively working on a couple of things. (The Boarduino being rather important for one of them as the PIC I currently have apparently doesn't have enough memory, and the Motorola HC11 is still too obtuse for me to understand it, which is slightly ironic because my favorite class in college was programming one of those, but that was over six years ago and we had the setup done for us and basically just had to write the code. I've what little assembly I had known back then is rusty enough that I am not patient enough to re-learn it just to try to implement my current project.)

The big score for the evening was a probe connector for the oscilloscope that I got from my (recently deceased) grandfather over the holidays. I didn't find a probe for the scope, and it had a very strange-looking connector where the probe was supposed to attach. It was a thick (comparatively) connector with a jagged edge and a hole in the center; I don't remember ever seeing anything like it before. But while I was at the store I did see connectors like that. It turns out that it's a UHF connector, and I was able to get the corresponding (male) plug for it that would convert it from RCA, and an RCA connector that I could then solder leads to. It was a bit of a shot in the dark, but when I got home and checked it the connection fit like a glove. I now have a semi-functional oscilloscope! (I still haven't soldered the leads to the RCA plug, but I shall soon).

Other scores for the evening are a little box to hold SD and other memory cards (I have a handful and this will help keep the ones that I am not actively using from wandering off) and a two-PS/2-to-one-USB adapter. This will theoretically be useful with keyboards and mice and laptops... and possibly with other things ^_^

So yeah, Baynesville Electronics Trip 1: Win! ^_^

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