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  1. KrisBlueNZ

    Project - Conveyor system using 555's

    Hmm. Neither can I. Both configurations (relay active when 555 output high, and when low) are shown on this page: http://electronics.stackexchange.com/questions/57025/0-10-second-on-time-with-a-potentiometer Search for "Linking to the light bulb", and the two diagrams are just below the heading.
  2. KrisBlueNZ

    Remote Control Circuit with CD4017 - counter decoder

    Hi! The 74LS92 is a member of the LSTTL logic family. It is not CMOS. It requires a power supply voltage in the range 4.75~5.25V so you would need a 5V regulator in the transmitter as well as in the receiver. It draws more current than the CD4024. It could be made to work, but some changes...
  3. KrisBlueNZ

    super capacitor capacity?

    Good point about leakage current Adam. I just did a quick sample of five types available from Digikey and here are the leakage current specifications for a 1F part: Nichicon UW: 500 µA maximum - far too high! Cooper Bussman PowerStor B series: 4 µA nominal, after 72 hours Elna DZ 2.7V: 200 µA...
  4. KrisBlueNZ

    super capacitor capacity?

    No, they don't have a power curve like a battery. If you mean a discharge curve, well, the discharge curve of a capacitor into a constant load current is a straight line. That's what the formula dV/dT = I/C means: for a certain capacitance, dV/dT (the rate of change of voltage - charging or...
  5. KrisBlueNZ

    super capacitor capacity?

    You're in a better position to know that than I am. But I will repeat my calculations in post #2 with the new values: C = 0.22F dV = (2.5 - 2.1) = 0.4V dT = C dV / I = 0.22 * 0.4 / 38e-6 = ~2300 seconds = ~40 minutes.
  6. KrisBlueNZ

    super capacitor capacity?

    All doable with the possible exception of transferring 100 µW over a 3~4 metre distance.
  7. KrisBlueNZ

    super capacitor capacity?

    OK, let's do some calculations. I'm going to assume that your circuit will be powered directly from the supercap at 2.7V and can tolerate a supply voltage as low as 2.5V. 1 second every 15 minutes is a duty cycle of 1/(15*60) = 1/900 = 0.1111%. That percentage of 30 mA is 33 µA. Plus 5 µA...
  8. KrisBlueNZ

    Open door

    Yes, you can connect the switches in parallel. They all need to be the type that's open circuit when the door is closed. So if it's a pushbutton type switch, which is held in the "pressed" position while the door is closed, it needs to be a "normally closed" pushbutton, because "normally"...
  9. KrisBlueNZ

    Stereo amplifier volume fades over time

    Thanks for the photos. Here are some disordered comments. It looks like there are two output ICs along the back edge of the board, with the white thermal goop on them. I assume you've unscrewed these from the heatsink to get the photo, right? It could be useful to know the markings on those...
  10. KrisBlueNZ

    Project - Conveyor system using 555's

    Yes, you can use relays. Drive the relay coil from the 555's output, and connect a diode across it as in these circuits: http://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcRPBvkCP26jf4gJMY6yuEuBfPszbC0vW0gosLLFSJBeRD79Wc442A (relay activates when 555 output is high)...
  11. KrisBlueNZ

    Hello, Welcome! (Introduce yourself)

    Welcome to Electronics Point, guys :-)
  12. KrisBlueNZ

    Joke components/circuits

    Well we might as well get the obligatory xkcd "circuit diagram" picture in here. From https://xkcd.com/730/
  13. KrisBlueNZ

    solar charge controller

    That's a pretty poor design. But here's a basic explanation of how it would work if a couple of corrections were made. Voltage from the solar cell comes in on the input connections at the left side, and the battery is connected to the output connections on the right side. When the voltage from...
  14. KrisBlueNZ

    PCB Software

    Have you rejected all of the packages you listed? If so, what were your reasons for each one? What's your budget?
  15. KrisBlueNZ

    Remote Control Circuit with CD4017 - counter decoder

    You're welcome :-) If you want, you can "Like" some of my posts or leave a comment on my profile.
  16. KrisBlueNZ

    Help identifying component

    That's great! Nice work.
  17. KrisBlueNZ

    The smallest 240vac to 12vdc power supply

    As others have said, you MUST have electrical isolation if you're powering a circuit that is not fully enclosed and insulated to relevant safety standards and/or has any external connections. No doubt it's a legal requirement; it's also a moral obligation. To my mind, there are very few...
  18. KrisBlueNZ

    Remote Control Circuit with CD4017 - counter decoder

    It's better that way. A transistor responds to the voltage between its base and emitter, and the purpose of C2 is to smooth Q1's base-emitter voltage. You can connect it from Q1's base to the 0V rail as in the original design, but then any noise or disturbances on the power supply will be...
  19. KrisBlueNZ

    The smallest 240vac to 12vdc power supply

    Yes, we really need to know how much current (or you could specify the power) you need at the output. Have a look at some teardowns of compact USB power units and chargers made by Apple and others. These have two PCBs in them, with SMT devices on both, and they supply 5V at around 1A maximum...
  20. KrisBlueNZ

    Identify this part

    Right, as Dave says, they're multi-layer ceramic capacitors (MLCC) in glass encapsulation. The value code 104M means 100 nF (aka 0.1 µF), ±20%. The 8549 could be a date code I suppose. E5 probably indicates the dielectric and/or the working voltage, but I can't find what those letters mean. It's...
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