Search results

Search Forums New Posts
  1. KrisBlueNZ

    Using Arduino to read bipolar signal (from plants)

    Regarding filtering... I'm not very knowledgeable about analogue filtering. What is the nature of the interference? Did you earth the soil that the plant is planted in? Would it be possible to do the filtering digitally? Regarding variable gain... Again it might be better to do this in the...
  2. KrisBlueNZ

    Time Delay Relay for caralarm-->gpstracker

    I think a simple resistor-capacitor delay will do what you want. I can't be sure because those documents don't give enough information on the output and input characteristcs, but it's worth a try. So you currently have a direct connection running from the siren control output of the alarm...
  3. KrisBlueNZ

    Interviewing

    Can you Skype him?
  4. KrisBlueNZ

    Alarm reset timer

    Not really. Just double-check and triple-check the connections up to and including the bridge rectifier. Any fault after the bridge won't cause any sparks to fly. R1 must be connected to the Phase wire from the mains plug, and the other side of the bridge goes to Neutral. I should have made...
  5. KrisBlueNZ

    Need help with a PSU schematic

    You don't need to simulate the regulators. You just need to simulate the transformer secondary, bridge rectifiers, smoothing capacitors and coupling capacitors. Once you've confirmed the DC voltages going into the regulators are high enough for the regulators to work properly, with appropriate...
  6. KrisBlueNZ

    Using Arduino to read bipolar signal (from plants)

    Hi arch, and welcome to Electronics Point :-) You're right. That circuit doesn't inject any current into the circuit being monitored. That design monitors voltages GENERATED BY the plant. GSR meters measure skin RESISTANCE, which requires some current to be passed through the skin being...
  7. KrisBlueNZ

    Need help with a PSU schematic

    Agreed Dave. It's the first time I've seen this trick as well. But I think it will work. The output current from the second bridge will be limited by the reactance of the capacitors. So it's like a voltage multiplier of some kind. There is no DC path from the transformer to the output, the way...
  8. KrisBlueNZ

    switch debouncing

    Right. That's a pretty good and widely used article. Ganssle's article includes a description of a pushbutton that generated an abberant, excessively long and poorly defined bounce signal on one specific test press. Personally, I think it's reasonable to consider that signal as a special case...
  9. KrisBlueNZ

    How to not hear Mylie Cyrus when I am playing guitar?

    LOL Chris :-) Seriously though, that's a fair point.
  10. KrisBlueNZ

    How to not hear Mylie Cyrus when I am playing guitar?

    I stopped drawing circles around transistors and other active components a LOOONG time ago. I think it was because I liked the look of the "equivalent schematic" drawings on IC data sheets. They also have the gently angled collector and emitter, which join part way along the base, instead of the...
  11. KrisBlueNZ

    Alarm reset timer

    OK, cool. You may want to add your location to your profile. It will appear in your posts. This is helpful to us, because it tells us which site we should refer you to, when suggesting components.
  12. KrisBlueNZ

    Photointerrupter latching encoder?

    Nice work Steve!
  13. KrisBlueNZ

    switch debouncing

    That's a good description Steve. There are a lot of ways to debounce switches. Before starting to write code, you should read Jack Ganssle's article on debouncing. Just Google those words and you'll find it. It's also been linked to in several posts in these forums. My article covers the...
  14. KrisBlueNZ

    Need help with a PSU schematic

    Yes, I would go with that circuit, with the addition of protection diodes across C9 and C10. Also, B2 doesn't need to be rated for 6A - you won't be able to draw much current from the 48V rail because of the impedance of C9 and C10, so a 1A bridge will be fine - and I don't see the need for D7.
  15. KrisBlueNZ

    How to not hear Mylie Cyrus when I am playing guitar?

    Yes, I remember seeing schematics with values marked in µµF. They were drawn before my time though. These days nearly everyone is comfortable using standard SI engineering prefixes, which are defined for every three orders of magnitude - femto, pico, nano, micro, milli, (units,) kilo, mega...
  16. KrisBlueNZ

    switch debouncing

    Whether it is or isn't a good idea to use an interrupt for pushbutton scanning really depends on the structure of the firmware. There are many approaches to firmware debouncing, but they all require periodic sampling of the input(s). Unless the remainder of the code is very compact and quick...
  17. KrisBlueNZ

    turn off circuit at low voltage

    Thanks guys :-)
  18. KrisBlueNZ

    DC Jack spark

    Good point Steve. Whether the laptop is already externally grounded shouldn't make any difference because the power adapter's output is fully isolated, but the connector mating order will determine whether the spark occurs inside the plug or at the barrel. The spark will occur at whichever...
  19. KrisBlueNZ

    Need help with a PSU schematic

    I'll put my two cents in with duke37 on this one. Dave, you need to consider the second bridge rectifier as piggy-backing onto the positive output from the first bridge rectifier. The DC sides of the two bridges are effectively in series, but they are powered from the same transformer winding...
  20. KrisBlueNZ

    FM Transmitter

    Have you tried asking on freelancer.com?
Top