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  1. rq3

    Are Rev-Ed & Picaxe missing out??

    @Rampz, I believe I have the same issue. I'm a retired analog electrical engineer. I can deal with Smith charts, and impedance matching. But sometimes (often) wrapping my head around software makes my brain bleed. Back in the 70's a colleague had designed a digital circuit (ECL) that ran under...
  2. rq3

    Tick Tock timing application

    Very nice! I was shocked what a difference it made adhering a mass to the piezo disc. And it certainly sounds like your clock is "in beat"! My only thoughts are that it's important not to restrain the piezo disc by clamping its edges. Just lightly glued or resting on a three point support will...
  3. rq3

    Tick Tock timing application

    You are over thinking this. A piezo disc will output over 90 volts if tapped directly. No amplication is required, indeed, you need to protect the ADC input with clipping diodes, but that is all that is required. Glue a nut or any other handy mass to the center of the piezo ceramic area to shift...
  4. rq3

    Tick Tock timing application

    Phil, you stole that clock! It's a beauty. Assuming its clean and properly lubricated, level the clock with good bubble level so that the case is vertical both left and right, and fore and aft. It also needs to be on a solid floor. Then adjust (bend) the pendulum crutch VERY carefully so that...
  5. rq3

    Tick Tock timing application

    A grinding wheel will put a small flat spot on a bearing ball in short order, unless it's tungsten carbide or similar. The clock in the video is a Tiffany tall case, purchased by the family of my great-great aunt somewhere around 1890. It's been running continuously for over 130 years, except...
  6. rq3

    Tick Tock timing application

    A 1/2 inch diameter steel bearing ball, with a flat spot for glue, works just as well. For glue, I use a high temperature epoxy called JB-Weld, but any epoxy should work. Just make sure the piezo ceramic and the ball are lightly scuffed. Epoxy doen't like to stick to silver very well (especially...
  7. rq3

    Tick Tock timing application

    Attached is a very brief video of one of my "TAP" sensors resting against the face of one of my clocks. It detects the escapement quite well. There is no amplifier at all. The piezo has back to back signal diodes to clip the potentially 90 volt signal from the piezo. There is a 100k resistor...
  8. rq3

    Tick Tock timing application

    I think I may have exactly what you need. It's a piezo sensor used to detect the contact of a 3D printer nozzle with its printing bed. It's PICAXE based, and I can even give you, and and only you, a working unit. Go here: https://reprap.org/forum/read.php?424,885697
  9. rq3

    Compact Date Storage & Retrieval

    I have a 48 year old HP-35 calculator that still works! As does my HP-67, after replacing its mag card drive rollers. But my 63 year old mechanical Curta "math grenade" is my go-to calculator, and the batteries have never worn out.
  10. rq3

    Hippy status, rev 2.0

    hippy, hippy, hooray!!! It's very good to see you here, and I'm going to take it as an indication that this planet is getting back to "normal", in a good way. You have been missed. Welcome home.
  11. rq3

    closed loop DC motor speed control

    This is a superlative idea! And should cost about $20 to implement. The projector mechanism should take the exact same number of motor steps to get from frame to frame, at which point the picaxe would output a pulse to trigger the video camera. Heck, you could probably crank the thing up so that...
  12. rq3

    closed loop DC motor speed control

    What you are describing is what used to be called a telecine ( pronounced telasinee). Unless there is an optical audio track involved, and you need high speed transfers, you are grossly complicating this. You seem to have a handle on the projection of the film image, and the exposure of the...
  13. rq3

    Farewell

    premelec, please know that you have been a great resource to a great number of people. I will miss you.
  14. rq3

    PicAxe Teaching System

    And an analog meter actually draws some current. Some years ago, after an exciting flight in a friends Beech-18 twin egine aircraft, in which the landing gear wouldn't extend, he showed me the troubleshooting he had done with his digital DMM on the landing gear switches. The DMM had an input...
  15. rq3

    Code structure - loop or goto

    Many thanks, Alan! You are a gentleman and a scholar.
  16. rq3

    Code structure - loop or goto

    Is there any particular benefit in terms of code size or execution speed between: Main: Do Stuff goto main and Main: do Do Stuff loop Just curious. I know goto's are anathema to some.
  17. rq3

    Constraints of Picaxe ICSP Programming?

    I went through this exercise a number of years ago. The 10k/22k input circuit was based upon the original RS-232 spec of +/-25 volts and the capabilities of the Microchip silicon (in particular the input protection diodes) at the time. The current Picaxe inputs are all CMOS with a very high...
  18. rq3

    power supply with large capacitance between regulator and 14M2

    Most linear regulator manufacturers strongly suggest a reverse diode across the regulator I/O if an output capacitor larger than 10-20 uF (regulator dependent) is used. The reason is that, should you short the regulator input, the large cap will discharge back through the regulator, and destroy...
  19. rq3

    More ADC questions and output questions

    Alan, I didn't state that well. The conversion is still 10 bits. Each bit holds 1 millivolt of resolution (1024 counts with a 1.024 volt reference). But the output is in two bytes. The lower byte, of two bits, holds the potentially worthless first two counts. The upper 8 bit byte holds the...
  20. rq3

    More ADC questions and output questions

    Well, a definitive answer that actually makes sense. Various Microchip products have different minimum ADC reference voltages because: 1) The FET switches that shunt the input signal to the sample and hold capacitor need a minimum internal supply to turn on fully. If they don't, then the...
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