I am trying to build a circuit to turn off an alarm when a passive infrared sensor detects a human in a room. Yes this is a bit backward but it is for turning off a door alarm when our receptionist is at her desk rather than detecting intruders. I know enough about electronics to just get myself in trouble (which isn't much), so any advice on parts and construction would be excellent. Thanks!
I want to drive 20ish LEDs, should I run them as series or parallel and why ? [more inside]
I was with a person that had an older style cell phone, I think it was an LG, but not sure. He was showing me pictures, but I was distracted with a series of around 10-12 numbers that were displayed on the screen, to the left and top of the picture area (not inside). They kept changing about once a second, each digit with no regularity. One would think that it may have been GPS coordinates but the numbers were too random and not changing in any particular sequence. What the heck was that? A tracking device? When I asked him what it was he very quickly deflected the question.
I can't quite get to the bottom of a USB peripheral auto-switching circuit diagram. [more inside]
Help me rediscover an electronics project from Radio Shack from back in the '80s. [more inside]
What is going on in LED lightbulbs? I mean the devices, not the industry. [more inside]
My USB Mic started picking up an omnipresent hum all of a sudden. It never used to. Any ideas what could have changed? [more inside]
Help me find a place to purchase this tiny car part for a Scion xB! [more inside]
How smart are smartpens? [more inside]
I am looking for an interesting or exciting video that would, in some small way, get Grade 7 kids excited about electronics or science in general. The video will be one part of a talk by Skype I'll be giving to a teacher friend's Grade 7 class. Ideally, the video would be less than 15 minutes and deal with electricity or electronics directly.
I tripped over an RCA cable connecting my amp to my laptop...and the RCA cable broke off, leaving the actual plugs stuck inside the amp. How the heck can I get them out? [more inside]
Help me identify a mystery component from the board of one of two damaged/crippled Nokia 6820 phones and determine if it's possible for me to get one working Frankenphone out of the two. [more inside]
Where can I get a replacement A1242 transistor? [more inside]
What are some reasonably complex and conceptually interesting electronics projects that I can make for my class? [more inside]
I'm trying to interrupt a standby timer on a DVD player for a homebrew projector dowser project and I need some help with capacitors and resistors. I've wired a momentary switch across the eject switch terminals to pop the cd tray from a distance. [more inside]
Where to source cheap LED strands? [more inside]
It's been cold recently (-15C) and I burned out two bulbs in my dutch bike's headlamp in a short time. Since the bulbs are hard to find, I thought this was a good time to replace the bulb with a 1-Watt LED light. What I built works, but I don't quite know why. [more inside]
Today I bought a Nokia 2730; stupidly, I took the battery out before taking it home. Now, even though it says the battery is charged, the phone won't work. Help! [more inside]
I am looking for recommendations for DIY synth kits. I recently built the Weird Sound Generator and Voice of Saturn kits and am now looking for more to build. Does anyone here know of any similar noise-making PCB kits, or something else in general I should look into? Thanks.
How can I connect my TV (via my stereo system) to my wireless bluetooth speakers? [more inside]
Cheap wall USB charger seems to interfere with iPod headphones, do I just need a better charger? [more inside]
I'd like to use a single 5mm UV LED (3.4Vf, 20-25mA) to charge a daub of glow-in-the-dark paint. It only needs to be lit around 1 minute of every 10 (or 6 seconds of every 60), and only when the (room) lights are out. What battery/circuit would be most economical to operate, and require the least-frequent battery changes? [more inside]
I am in search of a 3.5mm male-to-male coupler. [more inside]
vintage technology fi: help me connect a VCR to a TV [more inside]
What is the best way for me to sell (in the United States) an electronic device designed for the Japanese market? [more inside]
Recommend places to shop for cheap import electronics in Seattle. Think knockoff ipads, android tablets, unlocked smartphones, and other geeky gadgets straight off the boat from China...The kinda stuff you can get at sites like www.chinavasion.com
I have a lot of (old) ICs Integrated Circuits. (Also, crazy piles of capacitors and resistors, etc. but let us concentrate on the ICs.) Is there a website where an average citizen with these items can sell them to buyers? I fear they would just get lost buried or unseen on "ebay", even moreso on "craigslist". SeekIC.com seems like the kind of site I am after, but I would like to sell to buyers in the USA. [more inside]
My mother-in-law's old DVD player bit the dust recently and we would like to get her a blu ray player. She does not have internet and has a Magnovox 27 inch analog TV. She just wants to be able to view DVD and Blu ray movies. Any recommendations on a good, basic player?
My boyfriend has a Phillips 32" in flat LCD HDTV, that appears to be from 2006 or 2007. The screen seems to still be in great shape, but the speakers have developed an annoying buzz. Is it likely that the speakers could be fixed at a reasonable cost, or do we need to junk the tv completely and just get a new one?
What interesting projects can I make with my Arduino and scavenged radio parts or other household items? [more inside]
Can anyone recommend a good, inexpensive English-Spanish lexicon of TV/Cable/Broadcast technology terms? My sister does Spanish-language technical support for a large TV cable and Internet provider. She's first-language fluent in Spanish, but like many Spanish-speaking U.S. natives, leans heavily on Spanglish for many of the neologisms ("el remote") of the electronic age. [more inside]
Name this electronic component / construction technique! Found inside a late 1980s Datron 1081 bench multimeter. [more inside]
Recently, a friend's beat up old car was stolen the old fashion way - with a screwdriver to the ignition. This made me wonder about auto theft and newer, computer chip laden cars like the 2011 Volvo that I rode in yesterday. Has the computerization of automobiles led to new ways to steal cars? Basically, is there an car thief app for that?
Why does stuff disappear from Costco.com website without an out of stock indication? [more inside]
I finally figured out the perfect gift to get the boyfriend but am having trouble finding what I want. Help me navigate the world of diy audio kits with respect to guitar amps! [more inside]
where can i buy a dog door with a timer OR how can i make one OR is there somewhere i can commission such a thing? [more inside]
My 4.5 year old got to play with my friend's Ipod Touch, loved it, and is now adamant that Santa is bringing her one. This ain't going to happen. However, I would like to find her some kind of age-appropriate equivalent toy for Christmas. We don't do huge Christmas celebrations or massively expensive gift-giving, so this will be her big present, even if it's under $75. What can you recommend that won't make her ultra-disappointed (understanding that disappointment is a part of life, yadda yadda yadda)?
I need help parking in my apartment garage parking space. [more inside]
Does anyone make a thumb drive that plays MP3s? [more inside]
How can I wire a bass so that the volume and tone knobs are bypassed? [more inside]
Should I replace my MiFi with a hotspot-enabled Droid? [more inside]
Why does my TV signal disappear into static for minutes or hours at a time? [more inside]
I have a 5mW laser module. What do I need to attach it to to power it? [more inside]
Can I use my Kindle charger for my Blackberry Bold? [more inside]
Circular multi-segment LED displays? Who makes them? [more inside]
Where in Manhattan should I go to look at and possibly buy gadgets, electronics, and computery type stuff that would be hard to buy (excluding online) anywhere else?
Does a 120V AC -->12V DC power supply need an RF choke when used to power a small DC motor? [more inside]
Please recommend a "soldering mat" or other heat-resistant surface. [more inside]
I need an easy, yet cool-looking electronics project. In around one month, I'll be visiting Tokyo, including a day-long trip to Akihabara. Inspired by this post I think it would be really, really cool if I spent part of that day buying parts in order to create something electronic. Difficulty: I have close to zero experience with electronics. [more inside]
I'm going to travel a bit and might try to combine that with shopping. (a very novel notion, I know) Price-comparisons wanted. [more inside]