author8
25Instructables2,204,662Views2,859CommentsCambridge (UK),IRC@PKMJoined June 23rd, 2006

Tell us about yourself!

Complete Your Profile

Achievements

1K+ Comments Earned a gold medal
1M+ Views Earned a silver medal
Discover Green Science Fair for a Better Planet
Contest Winner Fourth Prize in the Discover Green Science Fair for a Better Planet
Let It Glow!
Contest Winner Second Prize in the Let It Glow!
Show 2 More »
  • PKM commented on randofo's instructable IPhone Camera Spinner18 days ago
    IPhone Camera Spinner

    So, if you can arrange it to turn the camera end-over-end at the right speed (which I did with a GoPro by crashing my quadcopter into the ground), the rolling shutter will make it take a nice 360 panorama as it rolls from sky to ground to sky again. Having only achieved it by blind luck I'm not sure how easy it is to synchronise with frame rate though...

    View Instructable »
  • PKM commented on SimonRob's instructable The Earth Clock4 weeks ago
    The Earth Clock

    Take that, flat earthers ;)

    View Instructable »
  • Keyrings Made From Ice Cube Trays and Pony Beads

    These look great, I love the look of the mixed purple beads one in the last image.This could be part of a great small batch manufacture process: build/carve/CNC/3D print a part, make a negative mould with pourable silicone, cast a bunch of pieces. That way you aren't limited by what you can find ice cube trays for :)

    View Instructable »
  • You can Google for the product name you have and "amps per meter", or "watts per meter" and divide that by 12? Even if it didn't come with any documentation someone online might know. If you're lucky you'll find a site like this that does the calculations for you http://www.ledlightsworld.com/page.html?id=38You could cut a short section, say 1m, and connect that to your wall wart with a multimeter set to amps in series with it. There's no way a 1m section will draw 5 amps so you'll be fine, your wall wart will happily power any demand up to 5A. (Some people worry that "my LEDs only need 1A but my supply puts out 5, will it blow up?" to which the answser is "no" - apologies if you already know this isn't how amps work)Or you could guesstimate, ...

    see more »

    You can Google for the product name you have and "amps per meter", or "watts per meter" and divide that by 12? Even if it didn't come with any documentation someone online might know. If you're lucky you'll find a site like this that does the calculations for you http://www.ledlightsworld.com/page.html?id=38You could cut a short section, say 1m, and connect that to your wall wart with a multimeter set to amps in series with it. There's no way a 1m section will draw 5 amps so you'll be fine, your wall wart will happily power any demand up to 5A. (Some people worry that "my LEDs only need 1A but my supply puts out 5, will it blow up?" to which the answser is "no" - apologies if you already know this isn't how amps work)Or you could guesstimate, as iceng says: each individual LED will use something like 10 to 20 milliamps, so if it's 3 LED in series and 60 LEDs per meter that would be (60/3)*20mA = 400 milliamps or 0.4A per meter, so you could probably power 10m of strip with your 5A supply.

    View Instructable »
  • PKM commented on boom man56's forum topic Arduino alarm clock help!5 weeks ago

    There are two ways of "pressing a button" on an alarm clock that should work on almost any clock: use a servo to physically press the button, or use a relay to connect the two contacts together. The servo can be more fiddly but means no electrical work on the alarm clock at all, the relay is an electrical solution that needs a bit more work.If you're using a servo, just physically attach it to the clock somehow with a horn positioned to press the button when you move it to a certain position. If using a relay, you'll want to connect the normally open (NO) and common terminals to the two wires on the button you are replacing. To drive a relay from an Arduino I think you'll need a transistor to drive the coil, a resistor for the transistor's base pin and a diode connected backw...

    see more »

    There are two ways of "pressing a button" on an alarm clock that should work on almost any clock: use a servo to physically press the button, or use a relay to connect the two contacts together. The servo can be more fiddly but means no electrical work on the alarm clock at all, the relay is an electrical solution that needs a bit more work.If you're using a servo, just physically attach it to the clock somehow with a horn positioned to press the button when you move it to a certain position. If using a relay, you'll want to connect the normally open (NO) and common terminals to the two wires on the button you are replacing. To drive a relay from an Arduino I think you'll need a transistor to drive the coil, a resistor for the transistor's base pin and a diode connected backwards across the relay coil to prevent flyback from harming the transistor or Arduino. There are probably many Instructables on driving a relay with an Arduino - the Aruidno website has a circuit diagram here http://playground.arduino.cc/uploads/Main/relays.p...Regarding making the Arduino wait for some time before pressing the button, you will want a main loop that continually checks whether the button is pressed. If it is, it can keep checking how much time has elapsed while the button is pressed until the desired time is reached, or reset the elapsed time if the button is no longer pressed. The code you linked only cares if the button is pressed when the timeout is reached and won't reset if the button is released during that period.You shouldn't need any kind of special power supply, if you are only driving a single relay you could probably do it with USB power from a phone charger as long as the relay is one that will switch with a 5V supply.------More general Arduino advice: If I was building a new project like this I'd try to break it down into parts. Write some code that will turn on an LED when you hold down a button for more than five seconds. Glue a servo to your alarm clock so the servo sweep code will press the button, or wire up a relay to turn on and off so you can flash an LED with that. Once you have all the parts, you can combine them into the complete project you want to make, and if you have problems with any individual part you can look for help with eg. relay control without involving the timing part of the code as well.

    View Instructable »
  • PKM commented on Sejma's instructable Some Cool Batch Applications5 weeks ago
    Some Cool Batch Applications

    -f means force shutdown without asking to close running applications. See more switches and their meanings at https://www.computerhope.com/shutdown.htm

    View Instructable »
  • PKM commented on bricobart's instructable Hole Saw Adze7 weeks ago
    Hole Saw Adze

    So is that metal stud in the last pictures just there to make it look like a horsey? Because it looks like a horsey.

    View Instructable »
  • PKM commented on Creativity Buzz's instructable MINI LAPTOP2 months ago
    MINI LAPTOP

    Well, I trust this more than the "how to make a DIY mains powered glue gun" video William Osman warned us about :) though it does use the same music which is a little unsettling. Maybe the battery powered screen isn't bright enough to show up well on video, maybe the one they made had some other issue like a broken ribbon cable and editing in a screencap was easier than fixing it, maybe the raspberry pi is too slow to make good video and they went with the smartphone advert "sequences shortened" approach :) whatever the cause, I'm relatively confident something like this could work even if it needs a couple of tweaks to perform properly.

    View Instructable »
  • PKM commented on PKM's instructable Astrophotography: Star Photo Stacking2 months ago
    Astrophotography: Star Photo Stacking

    Because we use stacking software to align all the photos together so you only ever see 10 seconds worth of star movement. 50 x 10s exposures comes out looking the same as a 500 second exposure where you re-oriented the camera to the apparent movement of the sky every 10 seconds. (This is the alternative approach: make a motorised mount which tracks the sky and then just stack all of your exposures directly on top of each other).

    View Instructable »
  • PKM commented on StephenCartwright's instructable Floating Data Landscape4 months ago
    Floating Data Landscape

    I saw the thumbnail and expected this to be "turn on your Hololens and fire up some 3d graphing software". It's all made of acrylic triangles and hand-bent angle connectors? That is some serious work!

    View Instructable »
  • PKM commented on bricobart's instructable 'Shave Mouse' Aka Revisited Shave Horse 8 months ago
    'Shave Mouse' Aka Revisited Shave Horse

    Bart's back!Hold on while I put goesting in my lexicon of words that will let me think about my situation better. So typical of the English, hygge (drinking hot chocolate in bed while wearing a woolly jumper) goes viral but we haven't caught on to a word that means "passion".Here's hoping the north Atlantic stays less windy for your crossing than it has been recently. I blame El Nino.

    View Instructable »
  • PKM commented on lingib's instructable CNC Pen and Wash Portrait9 months ago
    CNC Pen and Wash Portrait

    Seriously... this is embarrassing. I've been planning (plotting? har har) to build one of these for years, I just recently got my hands on a traditional X-Y plotter and started drawing things with it, and felt pretty pleased with myself that I'd generated a drawing with hatched shading so it could draw more than just linework. Then I see your instructables and you've done all the same stuff but to better quality and written an Instructable about it. I'll get back in my box...

    View Instructable »
  • PKM commented on Alex in NZ's instructable Fence Stake Driver9 months ago
    Fence Stake Driver

    It's called lean manufacturing :)When I was building this I went around the shop looking for food that came in the right size of can and that's what I had for dinner that day...

    View Instructable »
  • PKM commented on lingib's instructable CNC Pen Lift9 months ago
    CNC Pen Lift

    Did you publish this after seeing the analytics of me searching for about a hundred variations of "servo pen lift" last week looking for inspiration on how to build my own? Using tool clips is a great idea, probably more convenient than my "V blocks with elastic band superglued over them" holders.

    View Instructable »
  • PKM commented on Donald Bell's instructable Too $hort Cat9 months ago
    Too $hort Cat

    Also for hilariously awful borderline self-parody hip hop, may I suggest Slim Jesus's magnum opus "Drill Time"?

    "Something about this cat’s salacious gyrations spoke to me"There's a sentence I never expected to read. My headphones are broken so I can't really hear the music that well but I get the gist, and it's fantastic.

    View Instructable »
  • Folding Workshop Workbench! 折疊式工作臺!

    My shed definitely needs one of these. The only problem is I need another shed to put all the stuff from the first shed into when I'm using the workbench. Then that shed will need a folding workbench as well, which means ...

    View Instructable »
  • Make Mini Drone (Simple and Cheap)....!

    So on the existing helicopter (looks like a Syma S107 or clone) there are two counter-rotating blades for lift and rotation, and a separate vertical tail rotor for tilting forward/backwards. How do these controls let you tilt the drone forwards/backwards and left/right if the two pairs of motors are connected to the helicopter's two main motor connections?

    View Instructable »
  • PKM commented on AMAL MATHEW's instructable Quad Copter From Scratch10 months ago
    Quad Copter From Scratch

    Those motors look a lot heavier than most of the brushed motors I've seen on quadcopters- I just bought a Syma X5C and the motors are 7mm diameter, barely thicker than a ballpoint pen. Your motors are a lot bigger so will probably need much more lift, which will mean bigger props.The bigger problem here will be control: how do you propose to vary the speed of the motors when it's flying?You should definitely keep at it, you might well get this model flying while tethered to the ground - or alternatively, build a fixed wing plane and attach a long string to one wingtip so you can fly tethered outside. Once you've done that you can move on to adding R/C features and maybe have yourself something controllable :)

    View Instructable »
  • PKM commented on PKM's instructable Simple Arduino Sunrise Lamp11 months ago
    Simple Arduino Sunrise Lamp

    Hi Inga,I measured the LEDs drawing 650mA at 5V, which means the power was 5*0.65 = 3.25W. You could use whatever wattage of LEDs you wanted as long as your transistors are capable of switching enough current. Small electronics transistors like the 2N222A can only switch about half an amp so if you want more than a couple of watts you'd be better off finding some bigger power transistors or a dedicated LED driver device.I used an old Arduino Duemilanove, you could use whichever type you want as this project only needs one digital output pin. The code should work on any Arduino (but you might have to change pulsepin if yours doesn't have a pin 11).

    View Instructable »
  • PKM commented on brichtl's instructable Transfer Images to Fabric11 months ago
    Transfer Images to Fabric

    The oil you are using is this one https://artnaturals.com/artnaturals-lavender-oil-heals-burns-cuts-stings-and-bites-4-fl-oz-118-ml-15-00.html ? I was going to ask if it had any alcohol or other solvents in it but it doesn't look like it does from their description. I'd guess lavender oil is a stronger solvent than the usual edible oils. Perhaps you could make it work with a little rubbing alcohol or similar solvent in a different oil.

    View Instructable »
  • PKM commented on KarelK16's instructable Converting a Dollar-motor to Lego1 year ago
    Converting a Dollar-motor to Lego

    I think the outside diameter of those pieces is 7mm

    Just a thought- could you drill out the gear large enough to accept an axle connector like this one, so you could use whatever length of axle you wanted, or have it only protrude out of one side of the motor?

    View Instructable »
  • PKM commented on sdobbie's instructable Storing Files on an Audio Cassette1 year ago
    Storing Files on an Audio Cassette

    If the second trace is what you got back from the tape recording, your output level when recording is too loud. The signal is clipped (https://en.wikipedia.org/wiki/Clipping_(audio)) which means it's distorting and losing information. Great for electric guitar music, not so great for data storage.If you try it again, turn down the sound volume on your computer when you record the data to the tape. I'd do this with the output slider in Audacity- put the volume to 50%, let it play for a minute, turn down the volume to 40%, another minute, then 30% etc. You'll then be able to look at what recorded on the tape when you play it back and find the right volume where the audio waveform isn't distorted but is still loud enough.

    View Instructable »
  • PKM commented on dpeach's instructable LED Trunk Light Upgrade1 year ago
    LED Trunk Light Upgrade

    Ah! I was meaning to do this to my car over winter and I was intending to splice the LEDs in parallel with the bulb so both worked at the same time, but was put off by the idea of modifying the wiring. Using the festoon bulb holder to mount spade connectors is a great idea and completely reversable if you want to sell the car, maybe I'll revisit it

    View Instructable »
  • PKM's instructable Simple Arduino Camera Trigger's weekly stats: 1 year ago
    • Simple Arduino Camera Trigger
      99 views
      5 favorites
      0 comments
  • PKM commented on rschoenm's instructable Nested Helix1 year ago
    Nested Helix

    Because the first one is so pale, I saw the thumbnail and thought "huh, that's a neat 3D printing demo". Then I read the article and went "Holy ****, they are made of wood? How on earth..."

    View Instructable »
  • PKM commented on MRHoffman's instructable DIY Chicken Wire Ghosts1 year ago
    DIY Chicken Wire Ghosts

    I love it! Genuinely unsettling halloween decorations are my favourite, way better than smiling cartoony pumpkins and vampires (if you don't have to worry about terrifying small children).One tip: if you don't have glow in the dark paint but you're going to use a blacklight, highlighter ink glows strongly under UV light so you could use that instead. You can take the felt ink reservoir out of a highlighter pen and soak it in water to make your own glow fluid- see 3 Ways To Make Water Glow. This way you can even get different colours, though it won't be as bright as glow in the dark paint.

    View Instructable »
  • PKM commented on MWiggs's instructable Starcraft 2 Jim Raynor Armor1 year ago
    Starcraft 2 Jim Raynor Armor

    You and this guy need to meet up :)

    View Instructable »
  • Flawless geometric designs made with tape

    I guess this doesn't even have to be done with glaze on pots - you could use the same technique to apply, say, fabric paint to a plain cylindrical lampshade? As long as what you are using for the design doesn't dissolve the tape or bleed under it, it should be good.

    View Instructable »
  • PKM commented on fs woodworking's instructable The Wooden Light Bulbs1 year ago
    The Wooden Light Bulbs

    Clever! I have some leftover LED strip, might have to make one of these into a table lamp...

    View Instructable »
  • PKM commented on jessyratfink's instructable microwave cake1 year ago
    microwave cake

    I made this tonight but it was gone before I had time to take photos! I used Tejana15's suggested metric weights (65g flour, 55g butter) and cooked for 60s in a coffee mug in a 900W microwave, turned out pretty good! Nice springy sponge, the first crumbled a bit on taking it out of the mug because i overcooked slightly, the second had a tiny uncooked bit around the bottom edge where it was in the bottom corner of the mug - maybe don't use heavy walled containers as they suck the heat out while cooking.It smells quite strongly of egg and butter while cooking, but just tastes like sponge cake. I made mini victoria sponges with jam and whipped cream in the middle, the cream definitely helps as the cake was a bit dense in texture.One word of warning: according to this site (http://healthyea...

    see more »

    I made this tonight but it was gone before I had time to take photos! I used Tejana15's suggested metric weights (65g flour, 55g butter) and cooked for 60s in a coffee mug in a 900W microwave, turned out pretty good! Nice springy sponge, the first crumbled a bit on taking it out of the mug because i overcooked slightly, the second had a tiny uncooked bit around the bottom edge where it was in the bottom corner of the mug - maybe don't use heavy walled containers as they suck the heat out while cooking.It smells quite strongly of egg and butter while cooking, but just tastes like sponge cake. I made mini victoria sponges with jam and whipped cream in the middle, the cream definitely helps as the cake was a bit dense in texture.One word of warning: according to this site (http://healthyeating.sfgate.com/convert-fat-grams-calories-5127.html) there's over 900 calories in the single recipe (50*9 + 100*4 + egg and milk) before you start adding toppings, so make sure you have someone to share with! The whole thing took about 20 minutes start to finish so they are dangerously easy to make...

    View Instructable »
  • Grow Ten Tons of Organic Vegetables: Leeks, Onions, Potatoes, Broad Beans, Cabbage, Cauliflower, Sweetcorn, Courgettes & Marrows, Sugar Beet, Beetroot, Carrots, Swede, Kale, Calebrese & Broccoli, Brussel Sprouts & Strawberries

    "North west Wales on an island" - Anglesey?I'd be interested to see how your sugar beet wine/vinegar turns out. Aside from the strawberries, are you growing any fruits or aromatics you might use to flavour the results?

    View Instructable »
  • PKM commented on ModMischief's instructable Vibrator - a Layered Shot1 year ago
    Vibrator - a Layered Shot

    If you want something to do with almond liqueur you have sitting around, layer it with raspberry vodka and irish cream for a bakewell tart shot :)

    View Instructable »
  • PKM commented on unusual architect's instructable Dremel Table Saw1 year ago
    Dremel Table Saw

    "I needed to make a small insinuation"I think you might have meant "incision" there- an incision is a small cut, whereas insinuation means hinting or suggesting something. Just a thought.I like the look of this, although the table is quite small- if you made a bigger table this could be a really cool project.

    View Instructable »
  • PKM commented on bricobart's instructable Screwdriv'ify your knife1 year ago
    Screwdriv'ify your knife

    What paradise do you live in where hex-head wood screws are common? I went to buy a box of Torx head wood screws because I'm putting in and taking up floorboards so often in my wreck of a house, but the stupid hardware store had virtually none, all the wrong size and they cost something like £8 for 25. 100 Pozidrive screws were half the price, but at what price my sanity having to deal with all those mangled screw heads?

    View Instructable »
  • PKM commented on Penolopy Bulnick's instructable Unusual Uses for Mouthwash2 years ago
    Unusual Uses for Mouthwash

    I thought alcohol helped deal with head lice because they breathe through pores in their skin, and the alcohol poisons them. When I was a kid the DIY cure for head lice was methylated spirits on the hair- I wouldn't recommend that, but mouthwash with alcohol in (Listerine is over 25% alcohol!) may well have the same result.

    View Instructable »
  • PKM commented on EurekaFactory's instructable How to Fact Check2 years ago
    How to Fact Check

    I had a friend who used to send me all those chain emails witg crazy hoaxes in them- people selling perfume using ether to knock you out and mug you, spider eggs in new bras, that sort of thing. I made it into a game to see if I could disprove it with a reliable source (usually Snopes) while holding my breath. I told her about this game every time I got one of the emails and it must have sunk in eventually because she stopped sending them to me.The point was to demonstrate that checking an unbelievable story online isn't an arduous task, almost always a 30 second google will give you either corroborating sources or a "this is a hoax" writeup.

    View Instructable »
  • PKM commented on balsuryana's instructable From Old Motors Into Signal Booster2 years ago
    From Old Motors Into Signal Booster

    I wondered how signal boosters work, so I looked it up on Google. I found http://www.andybrain.com/extras/cellphone-antenna-... which I think tells you everything you need to know (they don't work at all and may make your reception worse).If you don't want to take this one guy's word for it (after his double blind experiment), what about the 184 people who gave this signal booster sticker a 1 star review on Amazon? https://www.amazon.com/Cellular-Innovations--BOOSTER-Universal-Antenna/dp/B00009WCAP/ref=sr_1_5?s=wireless&ie=UTF8&qid=1468241391&sr=1-5&keywords=signal+booster+sticker

    View Instructable »
  • PKM commented on Cactus workshop's instructable Vintage Oil Can Lamp2 years ago
    Vintage Oil Can Lamp

    20-W-40 - does that mean 20 to 40 watts? :)

    View Instructable »