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  1. hevans1944

    Oscillator

    Ah, yes! I totally agree. The ubiquitous 32.768 kHz clock crystal used in millions (maybe even billions by now) of cheap wrist watches and battery powered wall clocks is the logical and best choice for creating a one-minute clock pulse with an appropriate divider. I should have suggested it...
  2. hevans1944

    Oscillator

    Line operated or battery operated? 50 Hz power-line frequency? Easy enough to divide the power-line frequency with digital counter to create one pulse per minute. Or program a PIC to do that, which is the approach I would recommend. The absolute simplest PIC will be more than adequate for the...
  3. hevans1944

    Zeroing out a LM317 reference voltage with a zener - PSU build

    Okay, it's been a week and you probably have the voltage reference thingy by now. How did that work out? I think I see where I erred in saying C4 and D13 could be removed. If you connect D12 cathode where the + terminal of C4 is connected (at the common connection of D1 and D3), then C5 will...
  4. hevans1944

    How do I calculate the ESR of a capacitor please?

    Well, it is what it is. In this forum we don't discourage anyone from learning, because none of us here was born with an innate understanding of electronics and things electrical. Most of us acquired what we do know by the application of time and effort over long periods of time. But only you...
  5. hevans1944

    How do I calculate the ESR of a capacitor please?

    I went back and read your original post (April 12, 2016) on this topic. Your OBJECTIVE was to "develop circuits design and construction skills" and the due date is Friday, April 22, 2016. Based on your posts so far, I think you are not going to be able to finish on time. You have been given...
  6. hevans1944

    Windtunnel Airspeed Indicator

    If price is no object, then a Laser Doppler Anemometer (LDA) is the way to go. Can be calibrated using a method developed by NIST. See this PDF for calibration details. Some assembly required for calibration.:D
  7. hevans1944

    AC to DC Devices

    These components DO NOT all do the same thing. So your first task is to learn what they DO. Perhaps along the way you will also learn which one is most suitable in a circuit. It's going to be a long journey, but stick with it because the knowledge you gain will be worth it.
  8. hevans1944

    Esr Meter Build

    Did anyone notice that if you visit this link that there is a little box at the bottom right side of the page that lets you select your language of choice? There are also some really nice links on that page that are well worth the time to visit. The link to the very expensive commercial version...
  9. hevans1944

    On/Off Push Button Potentiometer

    That works of course. My hand-held 2m handy-talkie has a switch on its volume control knob that turns It off when twisted fully counter-clockwise. Many audio devices implement the same functionality, wherein it is desirable to turn on the audio without blasting you out of the room, which could...
  10. hevans1944

    How do I calculate the ESR of a capacitor please?

    You cannot calculate it. It is either measured or specified by the manufacturer. The goal you seek is to minimize the ESR. That may also require that you specify a maximum acceptable value, so you would need to look at specifications for candidate capacitors and make a choice. I doubt you want...
  11. hevans1944

    On/Off Push Button Potentiometer

    I finally remembered where I encountered the pot with push-button switch: an incandescent light dimmer! I hated that damn thing! It finally failed and I was able to replace it with a "standard" light switch that has a sliding dimmer control next to the switch. This I like because I can set the...
  12. hevans1944

    On/Off Push Button Potentiometer

    It has been many years since I encountered a pot with a push-button switch, and I didn't much care for that particular implementation: the pot tended to change position when I operated the switch. Things may have improved (or not) since the Chinese took over the market. Maybe you could try this...
  13. hevans1944

    On/Off Push Button Potentiometer

    Maybe Google can be your friend. Try looking at some of the links on this page.
  14. hevans1944

    volume to liter conversion

    Gee, doesn't the Metric System make calculations like this just a matter of moving decimal points around? IIRC, one cubic centimeter of water weighs about one gram. Google is your friend here. Or try this site to convert just about anything to anything.
  15. hevans1944

    Optocoupler symbol?

    So, I guess they are just opto-isolators. I do this any time I have to interface "real world" signals to expensive electronics, both for inputs (to the LED half) and for outputs (from the photo-transistor half). The use of a Darlington connection is usually required to actuate relay outputs, but...
  16. hevans1944

    Help with an ultrasonic rangefinder for blind people

    You might want to visit this Google page to see how others have approached this problem. The simplest solution is the red-painted "stick" that the blind often use to detect obstacles by swinging the rod back and forth in short arcs in a horizontal plane. No batteries required. But if you really...
  17. hevans1944

    Where can I buy a 20,000°/sec gyroscope?

    So be creative and add a boost converter to your coin cell. Or use multiple coin cells connected in series.
  18. hevans1944

    Optocoupler symbol?

    Good observation. I didn't notice he said "lathe controller" so these devices probably do act as sensors, typically as safety interlocks but also perhaps as limit switches. A hacker would probably disable them to get on with the real business of removing stock in the lathe.:rolleyes:
  19. hevans1944

    Wireless doorbell help

    In other words, put it back together, batteries or whatever included, power both units up and press the doorbell button on the transmitter (the thingy you call remote). If the thingy you call the receiver makes a noise each time you press the button on the remote... congratulations! You...
  20. hevans1944

    Wireless doorbell help

    Does not the original configuration already do that? You press the remote button and the bell "chimes". If you want to do more than that, you will have to "reverse engineer" the doorbell circuit, i.e., the "receiver" to intercept the signal that operates the bell (or whatever) and use that...
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