Electrical Engineering V2 - Developers

[QUOTE=false prophet;42158433]Can someone suggest a multimeter for a beginner? I'm wanting to measure amp, voltage and resistance in a number of things that would range from 240v AC to 24v DC. Budget of $25[/QUOTE] [URL="http://www.ebay.com/sch/Electrical-Meters-/66991/i.html?_nkw=multimeter&_udlo&_udhi=25"]Ebay[/URL] is your friend, but you won't get much, probably just the basics. A decent, beginner, "career" meter will run in the range of $40 - $70. For something specific, Ideal makes some quality ish meters.: [URL="https://www.google.com/#q=ideal+multimeter&tbm=shop&tbs=vw:l,price:1,ppr_max:50"]https://www.google.com/#q=ideal+multimeter&tbm=shop&tbs=vw:l,price:1,ppr_max:50[/URL]

Lol at the dissing of cheap meters. They're perfect for beginners or when you're in a pinch. Just don't expect them to be very precise in the millivolt range, that's really the only negative bit about them.

If you keep it to low energy any of those meters will do for some very basic stuff, but you should never ever attempt to use those cheap meters on mains or you risk it exploding. Also they are lacking many important basic features like auto-range, high input impedance, AC current and micro-amps. You'd be far better off saving up for a good meter, I'd not use those kind of meters if they was free. [QUOTE=Van-man;42158868]Lol at the dissing of cheap meters. They're perfect for beginners or when you're in a pinch.[/quote] Using those on mains is asking for trouble. If you really need to be cheap a vintage meter off ebay will provide both the performance and build quality. Somewhat better meters: [url]http://www.amazon.com/MASTECH-Manual-Digital-Multimeter-MS8268/dp/B000JQ4O2U/ref=sr_1_1?s=hi&ie=UTF8&qid=1378943307&sr=1-1&keywords=multimeter[/url] [url]http://www.amazon.com/UNI-T-UT202-Digital-Multimeter-Tester/dp/B00A13E1F6/ref=sr_1_16?s=hi&ie=UTF8&qid=1378943307&sr=1-16&keywords=multimeter[/url] [url]http://www.amazon.com/Amprobe-AM-500-Digital-Multimeter/dp/B008E07C1I/ref=sr_1_43?s=hi&ie=UTF8&qid=1378943711&sr=1-43&keywords=multimeter[/url] [url]http://www.amazon.com/Extech-MN35-Digital-Mini-MultiMeter/dp/B0012VWR20/ref=pd_sbs_indust_7[/url]

At the very least make sure to get an autoranging meter, and don't ever stick them into mains unless you either want to potentially die or paid sufficiently enough money for it.

Thanks. :) Analog circuits are a lot of fun so far. If I wanted to run say, 10 3v LED's on a single 9v source what would I need to do? Could I run 2 in series followed by another 2 in parallel until I met my goal? I'm not sure it would work that way...

[QUOTE=Chryseus;42159234]Using those on mains is asking for trouble.[/QUOTE] Makes me feel alive :c00l:

[QUOTE=DrDevil;42159344]At the very least make sure to get an autoranging meter, and don't ever stick them into mains unless you either want to potentially die or paid sufficiently enough money for it.[/QUOTE] [url]http://www.ebay.com/itm/UNI-T-UT136B-Auto-Range-Digital-Multimeter-AC-DC-Frequency-Resistance-Tester-/161050852215?ssPageName=ADME:L:OC:AU:3160[/url] I've been sticking this into mains, should i not be doing that?

[QUOTE=false prophet;42163148]Thanks. :) Analog circuits are a lot of fun so far. If I wanted to run say, 10 3v LED's on a single 9v source what would I need to do? Could I run 2 in series followed by another 2 in parallel until I met my goal? I'm not sure it would work that way...[/QUOTE] 2 LEDs in series and a resistor in a parallel string will work just fine. As always to calculate the resistor use: R = (Vsupply - Vdrop) / I In this case since you have two 3V LEDs in series Vdrop will be 6V. [QUOTE=SubbyV-2;42163997][url]http://www.ebay.com/itm/UNI-T-UT136B-Auto-Range-Digital-Multimeter-AC-DC-Frequency-Resistance-Tester-/161050852215?ssPageName=ADME:L:OC:AU:3160[/url] I've been sticking this into mains, should i not be doing that?[/QUOTE] Uni-T is a decent brand so I'd not worry too much about that, it's the really cheap Chinese brands you need to look out for. Well some of the even more expensive meters are a safety hazard, if in doubt get a Fluke, Gossen, HP / Agilent, BK Precision, Phillips or Extech (horrible range switch).

So today I've been at Altium where I demoed Altium Designer. Altium is a cool company and AD is a really fantastic product. Too bad it is so expensive though! I will probably have to nag my boss for a really long time...

Finally got my Hakko FX-888, the annoyances of my old RadioShack iron are no more!

Finally I managed to get an LC oscillator working after 3 days of painfully slow experimenting using my own design, (there is a serious lack of designs) this particular oscillator is a tuned plate tuned gate oscillator (TPTG) or I guess that'll be a tuned collector tuned base in this case, it's just a variant of the classic Armstrong / Meissner / Meißner oscillator. [img]http://u.cubeupload.com/Chryseus/TwVEel.png[/img] [i]L1 and L2 can be same value, L3 must be fairly large, preferably > 10mH, C4 may be smaller.[/i] [img]http://u.cubeupload.com/Chryseus/Rpf6I0.png[/img] [i]Output from base tank, note that it is not a perfect sine with some 2nd and 3rd harmonic.[/i] [img]http://u.cubeupload.com/Chryseus/Oc5ylN.png[/img] [i]Output from collector tank, really really nasty waveform but better amplitude[/i]

Designed a power inverter built into my car. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_0040.jpg[/IMG] The inverter itself had the on/off logic removed and a Cat 5 connector installed. I was missing the endplate so I brought out the 120v and fused 10a 12V lines. Up on the dash is the push botton and three status LED's that used to be on the inverter so now I can control it while it's installed int he vehicle body and all that makes you aware it's there is a wall outlet where the rear ashtray was.

Finished wiring in the inverter. [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_0047.jpg[/IMG] [IMG]http://i11.photobucket.com/albums/a166/ballsandy/IMG_0049.jpg[/IMG] It's doing one of those things computers do where it gives an error code which all documentations says does not exist. :v: It's not blowing up shit I connect and I can see that AC ground is not going to DC ground so I'm sure this is more one of those quirks you get from using a converter to simulate real AC power and a simulated sine wave.

My cheapo LC meter arrived today and it's surprisingly good for £26 including shipping, it can easily measure capacitance from to 10fF to 100mF and inductance from 1nH to 100H with a decent level of accuracy (datasheet specifies 5% to 1% depending on range), of course it doesn't do anything fancy like ESR or Q but it's excellent for the price. Only downside I've found so far is the cheap feel and a somewhat unhappy power switch, I'd still recommend it if you're on a budget, you can also power it from USB which is a bonus and it seems to work fine measuring in circuit (powered off of course). [t]http://u.cubeupload.com/Chryseus/b7jQFI.jpg[/t]

I'm looking at the recommended components to get, and most of them seem to be on Amazon. Is there anything wrong with using Amazon if I have a Prime membership? Seems like it would be a good price with free shipping.

[QUOTE=Cittidel;42213881]I'm looking at the recommended components to get, and most of them seem to be on Amazon. Is there anything wrong with using Amazon if I have a Prime membership?[/QUOTE] Hmm Amazon isn't too bad, although you would most likely get cheaper prices shopping from a proper electronics distributor like Allied Electronics, Mouser and Digikey, on the other hand Amazon do have some low cost resistor and capacitor packs which is nice. Basically if you're in a hurry go with Amazon or spend a little more time comparing prices. Ebay is also decent for some things like LEDs.

[QUOTE=Cittidel;42213881]I'm looking at the recommended components to get, and most of them seem to be on Amazon. Is there anything wrong with using Amazon if I have a Prime membership? Seems like it would be a good price with free shipping.[/QUOTE] Ebay has way better deals.

Expecially if you are starting from nothing. For £70 I managed to get packs of components for pretty much every value and type (For common stuff anyway) plus all the storage containers for it all. (Anyone in the UK, the pound shop currently have compartmented organiser boxes in! - Just add a bit of hot glue to the dividers and job's a goodun)

Thanks guys, if I were to go the eBay route I would imagine there would be some things to look out for/brands to avoid?

It depends on what you want to buy

Alright thanks again, I'm just going to follow what's in the OP as a starting point. I'm sure I can Google components to sort out the good from the bad.

So I grabbed one of [URL="http://www.alldatasheet.com/datasheet-pdf/pdf/55110/ALLEGRO/A3953SLB.html"]these[/URL] from an old printer. How feasible is it for me to use this IC in junction with an arduino to power a stepper motor? Sorry if I'm an idiot.

[QUOTE=SteelReal;42220197]So I grabbed one of [URL="http://www.alldatasheet.com/datasheet-pdf/pdf/55110/ALLEGRO/A3953SLB.html"]these[/URL] from an old printer. How feasible is it for me to use this IC in junction with an arduino to power a stepper motor? Sorry if I'm an idiot.[/QUOTE] Well, read the datasheet and decide yourself!

[QUOTE=SteelReal;42220197]So I grabbed one of [URL="http://www.alldatasheet.com/datasheet-pdf/pdf/55110/ALLEGRO/A3953SLB.html"]these[/URL] from an old printer. How feasible is it for me to use this IC in junction with an arduino to power a stepper motor? Sorry if I'm an idiot.[/QUOTE] It's for regular brush-motors only unfortunately. Might be able to rig something up for a bipolar stepper if you found another one though.

Late to the party, but why do you all seem to think auto-ranging on a multimeter is an important function? I have one, and I must say I prefer manual ranging to be honest (I also prefer bench multimeters, but that's another talk).

[QUOTE=BuG;42228447]Late to the party, but why do you all seem to think auto-ranging on a multimeter is an important function? I have one, and I must say I prefer manual ranging to be honest (I also prefer bench multimeters, but that's another talk).[/QUOTE] It's quicker and your less likely to make mistakes when reading, it's also an indicator what your buying isn't total garbage. That said everyone should have both a digital and an analog meter.

[QUOTE=Chryseus;42228937]everyone should have both a digital and an analog meter.[/QUOTE] Why?

[QUOTE=BuG;42228447]Late to the party, but why do you all seem to think auto-ranging on a multimeter is an important function? I have one, and I must say I prefer manual ranging to be honest (I also prefer bench multimeters, but that's another talk).[/QUOTE] If you prefer a manual ranging meter, then your auto ranging meter is crap.

[QUOTE=chipset;42231856]Why?[/QUOTE] It's easier to see a change in voltage / current on an analog meter than a digital one.

[QUOTE=ddrl46;42231997]It's easier to see a change in voltage / current on an analog meter than a digital one.[/QUOTE] UNLESS you get one of those digital meters that also has a "fake" analog dial thing.