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  1. KrisBlueNZ

    Mapper

    An LM3914 could be made to do this too.
  2. KrisBlueNZ

    Component questions (transistor, capacitor)

    I wouldn't expect any detectable amount of light from the LED when the switch is open. The maximum collector-emitter leakage current is specified as half a microamp. Maybe there's another leakage path - some flux residue that's become damp, maybe? Measure the voltage across the series resistor...
  3. KrisBlueNZ

    Rotation Switch

    Could this be done mechanically using centrifugal force? Back before ECUs, car engines had a centrifugal system in the distributor, I think, to adjust the timing according to the engine speed. That's not what you want, but you might be able to use the idea. Maybe... :-)
  4. KrisBlueNZ

    Designing a Converter!

    The 1.2V reference voltage at the reference IC is regulated by the reference IC and does not change significantly depending on the amount of current that is being drawn from the reference (within reasonable limits). Once you feed that voltage through a voltage divider made from resistors, the...
  5. KrisBlueNZ

    Designing a Converter!

    OK, here's my suggested circuit. This shows a single stage. The 1.2V reference is included, and its output voltage can be fed to other stages like this one. I have specified an OP-07 op-amp which has a much tighter input offset voltage specification than the MCP604x. This is important for...
  6. KrisBlueNZ

    Designing a Converter!

    Yes, there is a problem with the reference voltage circuit. You're using a voltage divider (3k8 and 1k0) to divide a 1.2V reference voltage down to 250 mV. That voltage divider has an output impedance which is equal to the parallel combination of the two resistors, which is about 792 ohms. In...
  7. KrisBlueNZ

    RGB controller

    Can that controller drive common anode LEDs? The common wire is black, which implies common cathode... Edit: Yes, the specifications say common anode. As you were, gents :-)
  8. KrisBlueNZ

    Op-amps and transistors for audio

    Hello MrD and welcome to Electronics Point :-) You're on the right track. But if you use an emitter follower to drive a speaker, you have to make the emitter resistor a fairly low value, to get a low output impedance. Since the emitter should be biased at around 1.3V (for a 3.3V supply...
  9. KrisBlueNZ

    Help in feed input of sensor with PNP output to controller (pic16f877a)

    I can't follow your description. Please post a schematic. Please include the part number of the sensor, so we know what we're dealing with.
  10. KrisBlueNZ

    Modifying 110v device to run on 240v

    Samon, you've already worked out that P = V^2 / R. Assuming R is roughly constant, P is proportional to V squared. That means that doubling the voltage will quadruple the power. This happens because doubling the voltage (for a fixed resistance) also doubles the current, and power is voltage...
  11. KrisBlueNZ

    flip relay with 2n3904

    Yeah, I'm afraid so. There's not much work here for design engineers and embedded systems programmers. But I'm always hopeful. Thanks for the comment :-)
  12. KrisBlueNZ

    (Electro)Magnetic Levitation

    How have you connected the LED? Can you post a schematic with the LED shown? That's what the circuit is supposed to do. When the Hall sensor output goes lower than 2.5V (or whatever voltage you've set on the trimpot), the op-amp's non-inverting ("+") input is lower than its inverting ("-")...
  13. KrisBlueNZ

    flip relay with 2n3904

    Thank you pilko :-) I have plenty of time because I'm unemployed, and I enjoy it.
  14. KrisBlueNZ

    12V Battery Charger Schematic

    I don't think you do understand. I've redrawn the schematic with a few points labelled, so I can explain it again. I've corrected an error that was present in the original schematic in the data sheet, and is present in your version. The op-amp inputs are reversed. The connection from downstream...
  15. KrisBlueNZ

    PIC16F913

    Infra-red remote controls use one of several standard protocols. They are well-documented on the Internet. Most use pulse-width encoding, where narrow and wide pulses indicate 0 and 1 data bits. If the data signal comes from an integrated receiver module, it is already demodulated. The signal...
  16. KrisBlueNZ

    PIC16F913

    Hi Joe and welcome to Electronics Point :-) Can you give us a bit more information? So you have an existing product that contains several PIC16F913 micros, and they receive digital data stream signals from some external controllers, and you want to identify the type of data and decode it, so...
  17. KrisBlueNZ

    Powering LEDs from batteries

    You posted this question on the end of an unrelated thread. I've moved it to its own thread. Start by reading https://www.electronicspoint.com/got-question-driving-leds-t256849.html There are many reasons why they might not work. Check that you've connected them the right way round. If...
  18. KrisBlueNZ

    Audio - mono to dual mono

    Are you recording a mono signal as a stereo track? You should be able to record each track (actually, each clip) as either mono or stereo. If you're recording as mono, you choose whether to use the left or right input channel of a stereo source (e.g. a sound card), and the other channel isn't...
  19. KrisBlueNZ

    Audio - mono to dual mono

    Sorry to disappoint :-( Sonar doesn't so much duplicate a mono signal to an "empty channel"; if you feed a mono signal into a virtual effect, it just feeds the mono signal into both left and right channels. It also has a channel mixing module that you can "connect" between the source signal and...
  20. KrisBlueNZ

    Audio - mono to dual mono

    Yes, exactly. No, I don't think so. The mic has a balanced, low-impedance output, which should be fed into a balanced input. RCA inputs are unbalanced, and jack inputs on standard sound cards are unbalanced too. You should be using a unit with an XLR connector. These used to be available as...
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