Here is a list of all the postings Robert Atkinson 2 has made in our forums. Click on a thread name to jump to the thread.
|Thread: Mains outlets with USB sockets - safety?|
Sorry Dave, but that's just not true. Modern electronics are not long life. The reduction ic size is the biggest problem as it causes higer power density and voltage gradients. The most common failure compnent is electrolytic capacitors.Many have specified lives (at max rating) of only a few thousand hours. Electronic failures are the most expensive repair on modern cars. This is not helped by technicians who just change boxes.
|Thread: Phillips vs Pozidrive and portable drills|
Mick said " Maybe we should all buy a 3 foot long yankee driver and bin the Bosch lol "
About 15 years ago I used to take machines to trade shows in the USA, The machnes were shipped in crates with lots of screws to open them . Having got fed up with short battery life on the cordless drivers back then and restrictions on carrying spare bateries on aircraft, I bought a yankee. Never goes flat (but you can wear out) and has automatic increased contact pressure with increased torque so hardly ever slips. Numerous people would come over and say " that's great, I'd fogotten about those" or similar. Not cheap but a great tool.
I use Xcelite which are available from RS Comoponents e.g.
but even then they are extended range.
Snap-On sell a set of L type ones but they will set you back about £150
It's not just simple Phillips / Posidrive. Two fairly common variations are the Japanese JIS which is close to phillips but less pointed. Then there is Supadriv which neither Phillips or Posidriv fit properly. JIS headed screws are often identified by a dimple on the head.
More esoterically there is RIBE/Polydrive (used on FCA nd GM vehicles) and Spline which look a bit like Torx. As an aircraft engineer I have also had to deal with Bristol spline TorqSet, Triwing and Hi-Torq.
Edited By Robert Atkinson 2 on 05/07/2019 19:33:22
|Thread: Phone charger|
Are they original Apple chargers or aftermarket items? Both the charger(s) and the Lead(s)?
How old are they and what condition are they in?
The spark you are seeing is from the EMI filter capacitor. While shorting it should not cause damage it would be better to just leave them unplugged for 5 minutes.
|Thread: Using a lathe|
SOD raises a good one " lack of imagination" this seem very prevalent these days. I deal with failure analysis and environmental / performance testing as part of my day job. Few engineers seem to be able to imagine what might go wrong or the consequences of the failure,. Some of it is down to experience, but they don't seem to be taught what my wife (an educator from the USA) calls "critical thinking". Many just accept any old rubbish on the net or even data/specification sheet. If a tolerance /rating/ performance figure isn't on the data sheet it's probably because it's not very good. A classic and repeated, electrical one is the metal clad "25 Watt" resistor which is only rated at about 7W unless it's on a foot square aluminium sheet or similar heatsink and even then gets to over 100 degrees C.
Curiosity starts at an early age and I think it's wrong to restrict it due to mis-placed safety worries.
It's also not just schools that restrict use of machine tools. As an "office worker" My employer says I can't use even a pillar drill because I don't have the correct "skill code" and enforces it by locking up the tools. This is despite being a qualified engineer (OK avionics, but the formal training did include machine tools) and using a fully equipped prototype machine shop at my previous employer.
Edited By Robert Atkinson 2 on 01/07/2019 12:53:17
|Thread: Mini Lathe - turning 6" long, 1.5" dia AL|
At 300mm between centres and a MT2 tailstock on the SC2 there should be no problem turning 6" between a chuck and centre. lots of choice in MT2 centres. why don't you think you can do it?
|Thread: Do you need one of these in your life?|
Nothing new there. Lots of variations on this out there. Mostly for bigger magnets. This one is quite nice
|Thread: Gents impulse clock|
that's more of a challenge as to how you capture the data without affecting the pendulum. A high frame rate camera and software would be one option. A more interesting one would be line CCD or diode array sensor like those used in document scanners sensing the shadow of the pendulum rod. This would give better resolution, easily 1024 positions, and require less processing. The sensor and lens from a flat bed scanner would probably work as is. Disconnect the sensor from the mechanical drive (initially leave that is as is for home and end sensors) and just try the scanning software. The image should be a sine wave.
I just realised I made a mistake on the OCXO accuracy. 31.5 seconds per year is 1x10^-6 if it all went out in the same direction at the beginning of the year. A more typical 1x10^-9 average is 0.03 seconds in a year.
Edited By Robert Atkinson 2 on 16/06/2019 21:50:34
The PICTIC I linked to (corrupted by smiley) "http://www.ko4bb.com/doku2015/doku.php?id=precision_timingictic" Google KO4BB (O not zero) pictic to find it
is ideal for what you want. run it from a 10MHz OCXO and a optocoupler obscured every pendulum swing and it will send the time of every swing to a PC via the serial port.
For a lowcost time interval counter with logging on a pc for checking clocks etc see
Any decent OCXO will be accurate to 1 part per million in a year (<1x10^6, HP's 10811A is more than 10 times better than that) so that's 31 seconds in a year worst case. Over shorter time scales eg days it's typically a thousand times better so 0.001 seconds per day. How good do you need?
|Thread: sulphuric acid|
I agree totally. Of the dozen or so cases it's probable that most are from own dogs. We get lots of complaints about dog mess in the village newsletter but few about the bottles, glassses and drink cans (cans get shredded by the councel mowers into razor sharp pieces). I reguarly pick up bottles and cans on the greens and playing fields. Septicemia kills hundreds in the UK every year so a cut while playing is potentially much more dangerous than dog mess. I am biased, I had septicemia from a cut in a park as a child and am a dog owner and ouy dog has had to have vet visits twice due to a cut paw.
|Thread: Gents impulse clock|
For clock setting you don't need a full GPSDO. Just get a Oven Controlled Crystal Oscillator (OCXO) or Temperature Compensated Crystal Oscillator (TCXO) with adjust ment and set it occasionally aginst a GPS. This is easy if you have an oscilloscope. Trigger the 'scope from the GPS 1PPS output (e.g.) put it on channel one) and monitor the output of the oscillator on one channel. The trace of the oscillator will drift across the screen. adjust it for minimum drift and it will be accurate to fractions of parts per million. you can then put the GPS away for 6 months. or more. This assumes it was already within 1Hz of nominal frequency.
Lots of OCXOs and TCXOs on ebay.
Robert G8RPI. (time nut, 5 GPSDO's, 4 Rubidium atomic frequency standards, HP 5370B etc).
You don't need the extra oscillator and phase locking for a master clock, just a divide by 30 on the 1pps output (an a flipflop to reverse the polarity every other pulse for a Gents. If you want to build a Miller style GPSDO you need one of the Jupiter receivers with a 10kHz output. I've got a couple if you are stuck. Andy G4JNT has some good info too.
Yes, that is a master clock. Nice find.
|Thread: Rover V8 drilling valve guides|
TR7? Surely it's a TR8 or haven't you told your insurers and the DVLA?
|Thread: High performance Torx bits|
+1 for Wiha or stop your local Snap-On van.
|Thread: Chinese speed controller|
A 12V (or better 24V e.g. truck) brushed DC motor like a wiper motor and a PWM controller would probably be a good opton for light work on a Pultra at higher speeds. PWM controllers are available on ebay and are cheaper than variacs and inherently safer being low voltage.
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