Newbie: tips on how to start?
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From: Bob Masta on 13 Jul 2010 09:06 On Mon, 12 Jul 2010 23:11:54 +0100, Rui Maciel <rui.maciel(a)gmail.com> wrote: >George Herold wrote: > >> What kinds of stuff are you interested in. Computers and micro's? >> Audio stuff, hacking existing products, blowing things up and making >> big sparks, Ham radio, electric power, robots,???? > >My short term goal is to be able to make terribly simple stuff, such as LED flashlights and solar- >powered fans, but it would be great if I could go from there onto building simple peripherals that >could interface with personal computers. Just so you don't get any false hopes, note that since the demise of DOS it has gotten *much* harder to build simple peripherals. Used to be you could use the parallel printer port for lots of neat interface tricks, from digital I/O to simple A/D and D/A. But printer ports are all replaced by USB these days, so a "simple" peripheral usually requires a not-so-simple USB interface and driver software. One thing that almost every computer has, however, is a sound card. This is not only something you can use to generate and analyze audio-range signals (see sig), but it can also be a way to interface certain devices to the computer. You have to deal with the fact that sound cards don't respond to DC, nor to really high frequencies, but that still leaves a lot of room for useful projects. As one simple example, you can use the sound card to measure frequency, so if you have some sensor (temperature, pressure, etc) that only responds to DC, you can build a simple voltage-to-frequency converter and use the sound card to measure the resulting frequency. > >> Do yu have any gear or access to it? Gear is the stuff you use to do >> electronics, oscilloscopes, signal generators, power supplies, >> voltmeters, and all that. > >No, I'm a bit empty-handed on this one. What gear do you suggest? I guess at least a multimeter is >in order. You absolutely need a DMM, but you can start out with a real cheapie. Harbor Freight has nifty little units that are often on sale for a couple of bucks... including battery! The drawback over a pro-level meter is that they don't have low AC Volts ranges (but they do have low DC Volts). So, use this as an excuse to build a little precision recifier and filter circuit, so you can read AC on the DC range. You can use the sound card to measure low AC volts, including true RMS (which cheap DMMs don't do), but you'll have to calibrate the inputs if you want absolute results... there is no way to get calibration data from the sound card driver, etc. But you can do a lot of useful things with only relative measurements, which don't require any calibration. (For example, distortion is a relative measurement.) But back to simple circuits: I always enjoyed sound-generating circuits. They can be as simple or complex as your abilities, and it's great fun to hear the results. The sound card can help you visualize the results, since it was designed for just this audio range. It wouldn't hurt to have a "real" hardware scope as well, but you can save that expense for later, when you really need high-frequency or DC capabilities. I use a 100 MHz hardware scope for general-purpose stuff, and the sound card (and software) for audio stuff. The "real" scope is an old analog model, so it doesn't have the fancy spectrum analysis features that you can get on high-end digital scopes. But (for me, anyway) I can do all that with the sound card, plus lots more (like color spectrograms) that the digital scopes don't do. Best regards, Bob Masta DAQARTA v5.10 Data AcQuisition And Real-Time Analysis www.daqarta.com Scope, Spectrum, Spectrogram, Sound Level Meter Frequency Counter, FREE Signal Generator Pitch Track, Pitch-to-MIDI DaqMusic - FREE MUSIC, Forever! (Some assembly required) Science (and fun!) with your sound card!
From: Cydrome Leader on 13 Jul 2010 15:57 JW <none(a)dev.null> wrote: > On Mon, 12 Jul 2010 21:06:30 +0000 (UTC) Cydrome Leader > <presence(a)MUNGEpanix.com> wrote in Message id: > <i1g04m$aig$2(a)reader1.panix.com>: > >>you can grab a cheap am radio, remove the cover and even just poke around >>at the parts while it's on. > > Battery powered of course, if poking with your fingers! haha, yes. So what does mains shock feel like in places with 240?
From: Jamie on 13 Jul 2010 16:32 Cydrome Leader wrote: > JW <none(a)dev.null> wrote: > >>On Mon, 12 Jul 2010 21:06:30 +0000 (UTC) Cydrome Leader >><presence(a)MUNGEpanix.com> wrote in Message id: >><i1g04m$aig$2(a)reader1.panix.com>: >> >> >>>you can grab a cheap am radio, remove the cover and even just poke around >>>at the parts while it's on. >> >>Battery powered of course, if poking with your fingers! > > > haha, yes. > > So what does mains shock feel like in places with 240? Hmm, it hurts..
From: Sjouke Burry on 13 Jul 2010 16:39 Cydrome Leader wrote: > JW <none(a)dev.null> wrote: >> On Mon, 12 Jul 2010 21:06:30 +0000 (UTC) Cydrome Leader >> <presence(a)MUNGEpanix.com> wrote in Message id: >> <i1g04m$aig$2(a)reader1.panix.com>: >> >>> you can grab a cheap am radio, remove the cover and even just poke around >>> at the parts while it's on. >> Battery powered of course, if poking with your fingers! > > haha, yes. > > So what does mains shock feel like in places with 240? It makes you see stars, and makes your muscles contract violently. And there might be a small burn mark. Having good quality plastic soles under your shoes makes single contact oke. Dont use leather soles. My limit fo far is 2X500 volt from a falling radio I tried to catch..... We both survived. Automatic reflexes are so dangerous when you work with electricity.
From: John Fields on 14 Jul 2010 08:04
On Mon, 12 Jul 2010 14:47:45 +0100, Rui Maciel <rui.maciel(a)gmail.com> wrote: >I'm looking into picking up electronics as a hobby. What advice can you spare? --- stay away from sci.electronics.design. ;) JF |