author
3Instructables5,594Views64CommentsMelbourne (Australia)Joined November 10th, 2007
The thumbnail shows me explaining angular momentum to mum.

Achievements

  • Caspar commented on adafruit's instructable PIR Motion Sensor Tutorial12 days ago
    PIR Motion Sensor Tutorial

    Its not a Fresnel lens, rather a set of small lenses each of which focusses a heat image onto the detector. As someone walks past, a series of (hot) images cross the detector (with gaps in between). The circuit relies on a series of hot-cold-hot-cold signals before it registers. So it's a "motion sensor". The lens is polyethylene becaust it transmits IR radiation. (Glass absorbs IR)

    View Instructable »
  • Caspar commented on LargeMouthBass's instructable Stop Time With an LED Stroboscope!7 weeks ago
    Stop Time With an LED Stroboscope!

    For high speed work, you may need a single colour LED. White LEDs have a phosphor which takes time (maybe a millisecond) to fully stop emitting light.

    View Instructable »
  • Caspar commented on cutprogram1's instructable How to Accuratly Measure Between Two Holes11 months ago
    How to Accuratly Measure Between Two Holes

    If holes are the same size, measure one of them and re-zero the vernier (it must be the digital type). Note that the zero now showing is the distance between 2 fictitious holes, one directly over the other. (Duh!) So now measure the distance from the outer edge of one hole to the outer edge of the second. Voila !

    View Instructable »
  • How to Make a Touch Switch Using One Mosfet

    I understand that the circuit was so simple that it could be drawn on a chalkboard. As a retired electronics engineer of 30+ years, may I suggest that a combination of a photo of the completed assembly and a "proper" schematic circuit diagram would be very useful in educating other electronics newbies. The photo would show all the wires clearly, and where they went to, and maybe include some little paper labels for clarity. If the construction was to be packaged, an exploded view might make for a better photo. The schematic would show pin numbers, voltages, and useful notes for the hobbyist. I couldn't work out how the touch switch worked, and think it was due to a capacitance effect or static electricity on the person. A data sheet showing the high insulation of the gate, and...

    see more »

    I understand that the circuit was so simple that it could be drawn on a chalkboard. As a retired electronics engineer of 30+ years, may I suggest that a combination of a photo of the completed assembly and a "proper" schematic circuit diagram would be very useful in educating other electronics newbies. The photo would show all the wires clearly, and where they went to, and maybe include some little paper labels for clarity. If the construction was to be packaged, an exploded view might make for a better photo. The schematic would show pin numbers, voltages, and useful notes for the hobbyist. I couldn't work out how the touch switch worked, and think it was due to a capacitance effect or static electricity on the person. A data sheet showing the high insulation of the gate, and the voltage needed to turn it on would be useful. Others commented negatively about the lack of schematic, and I found myself frustrated also. Pictures and talking are ok, but "A schematic is worth a thousand words" ps. just noticed your night-light circuit. A good way to combine a photo and schematic in one. For your next version (230V), you may want to include some notes on safety.

    View Instructable »
  • Caspar commented on lonesoulsurfer's instructable Lightening Detector and Counter1 year ago
    Lightening Detector and Counter

    "Lightning", not "Lightening"

    View Instructable »
  • Caspar commented on bekathwia's instructable Solar Soil Moisture Meter With ESP82661 year ago
    Solar Soil Moisture Meter With ESP8266

    My point was that 2 holes were needed, not just one. To illustrate: I had to troubleshoot a meteorological cloud searchlight (a light aimed up at 45 degrees so that an observer some distance from the base of the light could measure the elevation angle of the spot where the light hit the clouds, and using some tables could estimate the cloud height. Superseded by laser and radar methods these days) But I digress. The problem was that the searchlight glass misted up which caused the light do diffuse too much. I found that the asbestos seal (yes - it was a long time ago) had just one notch cut out at the bottom as a drain hole. I simply cut another at the top to let water vapor out. Solved. With regard to your Temp/RH sensor, the sintered metal(?) covering should have a hydrophobic lay...

    see more »

    My point was that 2 holes were needed, not just one. To illustrate: I had to troubleshoot a meteorological cloud searchlight (a light aimed up at 45 degrees so that an observer some distance from the base of the light could measure the elevation angle of the spot where the light hit the clouds, and using some tables could estimate the cloud height. Superseded by laser and radar methods these days) But I digress. The problem was that the searchlight glass misted up which caused the light do diffuse too much. I found that the asbestos seal (yes - it was a long time ago) had just one notch cut out at the bottom as a drain hole. I simply cut another at the top to let water vapor out. Solved. With regard to your Temp/RH sensor, the sintered metal(?) covering should have a hydrophobic layer to allow water vapor but not water through. I tried dipping a plastic RH sensor in clean water to remove salt mist from sea spray, but it never worked after that.

    View Instructable »
  • Caspar commented on bekathwia's instructable Solar Soil Moisture Meter With ESP82661 year ago
    Solar Soil Moisture Meter With ESP8266

    In my career as a scientist, I made lots of sensors for outdoor work. My mantra was: "If you can't hermetically seal the enclosure, ventilate it." Ventilation means 2 holes at least, otherwise changes in air pressure or temperature will allow moist air in, and in accordance with Murphy's Law, it will condense on circuit boards and not escape. So I filled connectors (for ocean use to 200m) with vaseline, pushed (flowable) silastic into the voids between conductors in a cable, potted electronics etc.

    View Instructable »
  • Caspar commented on mikeasaurus's instructable Unusual Uses for Magnets1 year ago
    Unusual Uses for Magnets

    Plastic bags are ok but too pliable to release the steel items easily. I use a strong magnet and a thin walled plastic dish (drink bottle, yogurt tub...) . Run the dish over the area, then lift the magnet to release the steel.

    View Instructable »
  • Caspar commented on DevCoder's instructable How to Build a Tesla Coil1 year ago
    How to Build a Tesla Coil

    Don't forget it sparks generate ozone. If you can smell it, it's above the safe exposure limit.

    I agree. And if the glass is very clean and dry there will be no surface leakage. I have used stacked perspex and Al foil to make a HV cap.

    A teaspoon of salt should be ample.

    View Instructable »
  • Caspar commented on wilgubeast's instructable 11 Unusual Uses for Baby Oil1 year ago
    11 Unusual Uses for Baby Oil

    Sorry, Codswallop, a better term to describe it would be "mineral oil". Nothing like paraffin or paraffin oil.

    View Instructable »
  • Caspar commented on wilgubeast's instructable 11 Unusual Uses for Baby Oil1 year ago
    11 Unusual Uses for Baby Oil

    Paraffin oil. It used to be available in supermarkets.

    View Instructable »
  • Smart Lock USB. Use Magnet Polarity to Unlock and Lock Usb.

    Does the Hall sensor short the data lines? I like it but wouldn't a reed switch do the same?

    View Instructable »
  • Caspar commented on tomatoskins's instructable Double Marble Puzzle1 year ago
    Double Marble Puzzle

    My grandparents had a pressed metal one, 2" square with diagonal grooves and an end stop in the middle to keep 4 balls in their own tracks. The top cover was celluloid. Polycarbonate was not around in 1950. Spinning the toy briefly would bring the balls to the corners. I could do it in a second (behind my back, which mystified my school mates).

    View Instructable »
  • Caspar commented on mikeasaurus's instructable Unusual Uses for Zip Ties1 year ago
    Unusual Uses for Zip Ties

    They can be joined together to make a longer one.

    btw: If using to secure a rubber hose to a metal pipe, wrap the tie around twice to reduce the possibility of a leak where the zip could pinch the hose.

    You forgot to mention holding burglars until the police arrive, or on the other hand, tying up home-owners while you ransack their houses. ;-)

    Someone mentioned using a pin to release the ratchet to undo the tie. There are ties available with extended ratchets to enable easy undoing.

    View Instructable »
  • Extend Defective Fluorescent Tube-Light Life

    I made something similar in the antarctic in 1972. A motor-start capacitor across the tube, value chosen to be series resonant with the existing choke. It could boost the voltage across the tube to 1000V, enough to start the fluoro at -30 degrees C, without the starter. The situation was quite tough for the tube and it only lasted a few weeks then the capacitor blew up.

    I made something similar in the antarctic in 1972. A motor-start capacitor across the tube, value chosen to be series resonant with the existing choke. It could boost the voltage across the tube to 1000V, enough to start the fluoro at -30 degrees C, without the starter. The situation was quite tough for the tube and it only lasted a few weeks then the capacitor blew up.

    View Instructable »
  • Caspar commented on inconceivable1's instructable Arduino Light Sensitive Door Bell1 year ago
    Arduino Light Sensitive Door Bell

    Please, as a general rule, could you tell us in the first sentence or two what your device is for. Then immediately after, how it differs from those in the market already. Going straight in with "You will need..." or "I made this from some scrap..." will not attract readers to continue reading. (This applies to many Instructables, not just yours)

    View Instructable »
  • Caspar's instructable Drill bit gauge from 12 inch steel ruler.'s weekly stats: 2 years ago
    • Drill bit gauge from 12 inch steel ruler.
      1,864 views
      26 favorites
      3 comments
  • Caspar commented on Caspar's instructable Unsoldering Difficult Pcb Components.2 years ago
  • How To Publish An Instructible From Your Ipod/iphone

    Thanks. I have a desktop pc but eschew i-XXXX devices.

    View Instructable »
  • Extract FREE Silver From Relay Contacts | Where to Find Them?

    Just be aware that relay contacts are often alloys containing silver. High current contacts have cadmium (makes poisonous fumes from heating it) . Low current contacts are more likely to be pure, and often have platinum or palladium in them.Some have a gold plating over Ag/Cd alloy so can be used for low level (micro-volt and micro-amp signals) until the gold wears off. Many years ago I was able to extract silver as black silver sulphide precipitate, by adding hydrogen peroxide to about 10 litres of spent photo fixer. After heating (oxy-acetylene torch) I retrieved about 200 grams.

    Just be aware that relay contacts are often alloys containing silver. High current contacts have cadmium (makes poisonous fumes from heating it) . Low current contacts are more likely to be pure, and often have platinum or palladium in them.Some have a gold plating over Ag/Cd alloy so can be used for low level (micro-volt and micro-amp signals) until the gold wears off. Many years ago I was able to extract silver as black silver sulphide? precipitate, by adding hydrogen peroxide to 20+ litres of spent photo fixer. After heating (oxy-acetylene torch) I retrieved about 200 grams.

    btw: In 1966 the treasurer in Australia INSISTED that the new 50 cent coins have 50% silver content. At the time the silver content alone was worth 73 cents, so the coins didn't stay in circulation very long!

    View Instructable »
  • Build a World's Smallest Electronic Shocker!

    Brilliant! They could call Allen keys "honeycomb" too. Any more suggestions for tool names?

    View Instructable »