Search results

Search Forums New Posts
  1. KrisBlueNZ

    LED optic sensor circuit

    OK, here's what I think you probably have: And here's your image annotated to match mine: The difference is the bottom resistor, which I've drawn shorted out. I don't see any reason why there would be a resistor in that position. That's why I asked you to check that there really is a...
  2. KrisBlueNZ

    Multiplying Voltage by a factor

    Sounds like you want some kind of auto-ranging system like multimeters have. This requires a variable attenuator that selects between several attenuation factors (often with 10:1 ratios) under software control. You need to tell us a lot more about your application and requirements.
  3. KrisBlueNZ

    adding a start capacitor to a circuit

    Thanks for the info :-)
  4. KrisBlueNZ

    adding a start capacitor to a circuit

    So that's a "probably not" then? How about another crazy idea - a variac driven by a geared motor? The motor would have to wind the variac down to zero when the thermostat switched OFF, then when it switched ON, it would wind the variac slowly up from zero. Sounds too silly? Probably...
  5. KrisBlueNZ

    adding a start capacitor to a circuit

    Duke, would it be feasible to add a heavy duty NTC thermistor in series with it to limit the start current? Just a crazy thought...
  6. KrisBlueNZ

    3 phase stray voltage

    I agree with Steve. I would get your system checked out by a registered electrician, if you haven't already done so, and set a yearly alarm to remind you to do a visual inspection of your distribution board, earth stake, and anything else the electrician recommends. I would suggest installing...
  7. KrisBlueNZ

    LED optic sensor circuit

    Hi Lance and welcome to Electronics Point :) OK, most probably, LED1 is an infra-red LED and "LED2" a phototransistor. The LED is needs to be fed from a supply voltage via a resistor; this will be the top resistor in your diagram, feeding the anode of the LED on the left side of the "LED1"...
  8. KrisBlueNZ

    Evaluating a cap. power supply in LTSpice

    Great! In the real world, resistors aren't available in all possible values. There are several series, called E6, E12, E24, E48, E96 and E192, that define what values are available. The E-number is the number of different values in each decade; E12 uses twelve values: 10, 12, 15, 18, 22, 27...
  9. KrisBlueNZ

    simple fm receiver

    In that case, I have nothing more to add. I have no idea how that circuit is supposed to work! I'm not saying that it won't, of course; simply that I personally don't know how it would.
  10. KrisBlueNZ

    Evaluating a cap. power supply in LTSpice

    No, I wouldn't worry about resistor tolerance. How accurate is your 10V AC anyway? If it's derived from the mains, it won't be better than ±10% or so anyway. That's why it's normal to choose components conservatively. For that circuit, with a 330 ohm resistor, I wouldn't use an LED with a peak...
  11. KrisBlueNZ

    Connecting Circuit to 12V Power Supply

    No problem. Good luck!
  12. KrisBlueNZ

    Evaluating a cap. power supply in LTSpice

    Yeah, I prefer to let LTspice do it for me.
  13. KrisBlueNZ

    Connecting Circuit to 12V Power Supply

    No, I can't tell from the photo whether the receiver has a momentary or toggle output behaviour. The eBay page you linked to has a description of behaviour for your old receiver: I guess you want the "self-lock" behaviour. There is no similar description on the page you linked to in post #3...
  14. KrisBlueNZ

    Connecting Circuit to 12V Power Supply

    So you were assuming that when you press the button, the output will turn ON, then when you press it again, it will turn OFF, and so on? This is described as a "toggle" action. What you're seeing is a momentary action. The behaviour of that receiver is not described in the eBay page. There may...
  15. KrisBlueNZ

    Connecting Circuit to 12V Power Supply

    OK, it looks like you're nearly there. You've got your battery connected to the power connector on the board, but I'm not sure if you have the lights connected properly. Here's what you should have. Battery positive ---- to board power connector positive ---- also to COM1 terminal ---- also to...
  16. KrisBlueNZ

    Evaluating a cap. power supply in LTSpice

    OK, here's the full LTspice simulation. The green trace relates to the voltage markings on the left side of the graph, and shows the voltage at the top of R1 relative to the bottom line of the circuit (that's connected to the downwards-pointing triangle). As you can see, the voltage at the...
  17. KrisBlueNZ

    simple fm receiver

    So the Siemens BF255 and the Thomson CSF BF255 have different pinouts? You know how to check the pinout of a transistor using a multimeter on diode test range? If not, try http://www.google.com/search?q=determine+transistor+pinout+using+multimeter
  18. KrisBlueNZ

    Connecting Circuit to 12V Power Supply

    Without knowing what you're doing, we can't tell what you're doing wrong. What are you using as your power source? How are you connecting it to the board? Can you show us a photo? Why do you think you've "blown" two boards already? What information came with the boards? Can you photograph or...
  19. KrisBlueNZ

    simple fm receiver

    An old data sheet at http://www.rf-microwave.com/datasheets/4997_Thomson-xCSF_BF255_01.pdf has this pinout: This is different from the BF199 pinout in post #1.
  20. KrisBlueNZ

    Evaluating a cap. power supply in LTSpice

    Here's about the simplest way to power an LED from 10VAC. V1 is a 10V AC source. "10V AC" means 10V AC RMS, which is actually a peak voltage of 14.14V. (This value is sqrt(200).) That's why the voltage is shown as 14.142V. And you can ignore the + and - symbols in the circle. R1 limits the...
Top