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  1. KrisBlueNZ

    Translation and Explanation of Diagram

    Wow, AUD 3! That's very cheap! And I don't necessarily just mean that in a good way! Yes, you can just cut the plug off the end of the cable, strip off the outer insulation, separate the screen from the centre conductor, twist up the screen wires, strip the centre conductor, and connect the...
  2. KrisBlueNZ

    Translation and Explanation of Diagram

    OK so you already have a controller for the garage door. So you will just be "extending" the button, so the button on the remote control transmitter will just be connected in parallel with it. That should work fine; you just need to check that the receiver's relay contacts close while the...
  3. KrisBlueNZ

    Circuit is not working

    Yes, it sounds like the 8.2V zener might be leaky. You should probably use a 400~500 mW device; 1W zeners have a higher leakage current. Also you could try adding a trimpot from the transistor's base to ground, perhaps try 10K. This circuit seems a bit odd. There are two voltage feedback paths...
  4. KrisBlueNZ

    Wood for the Trees

    Hi Michael, Thanks for your thorough description of the problem. I think you will need a microcontroller such as the Arduino, driving a DAC with a fairly high resolution to do what you want. You're right that an 8-bit PWM is not going to be workable, both because of the low resolution and...
  5. KrisBlueNZ

    Translation and Explanation of Diagram

    Yeah, as Dave said, the receiver seems to want 12VDC at 7 mA idle current (more when the relays are activated, so aim for 12VDC at at least 100 mA). The output is on the two sets of relay contacts labelled A,B,C. Exactly HOW the contacts operate in response to the transmitter button(s) is not...
  6. KrisBlueNZ

    DAQ sensor simulator, help please?

    Your post isn't clear: do you want to actually connect sensors to your DAQ board, or simulate them? You can easily simulate a sensor using a potentiometer. Your DAQ board probably accepts a current or voltage with a defined range, e.g. 4~20 mA or 0~5V. You just need a voltage rail (which may be...
  7. KrisBlueNZ

    Digital Clock

    A similar recent thread on this topic: https://www.electronicspoint.com/building-digital-clock-t249609.html
  8. KrisBlueNZ

    LDR circuit ( Application of transistor as switch)

    It might be simpler to put the current shunt on the board and use a multimeter measuring voltage to display the current. For example if you choose a current shunt resistance of 1K, you put a 1K resistor in series with the base, with a 2-pin connector connected to the two ends of it. The circuit...
  9. KrisBlueNZ

    Chat_Ghosty's PSU

    Right. If those figures are marked on the drive, then the power supply should be rated to deliver at least that much current on those voltage rails. The power supply doesn't have any heatsinking or fan because it will be a switching power supply and these are relatively efficient so not much...
  10. KrisBlueNZ

    Chat_Ghosty's PSU

    Yes, that rating is for a replacement fuse. Fuses are rated in amps, not amp-hours. Batteries are rated in amp-hours. T2AH is a 2 amp "time-delay" fuse (i.e. not quick-blow - it takes a short time to blow, so it will withstand the inrush current when the supply is turned on). I think the H...
  11. KrisBlueNZ

    Chat_Ghosty's PSU

    Unless having stuff you don't need means a lot more work and you can actually get by with what you already have!
  12. KrisBlueNZ

    Chat_Ghosty's PSU

    Those examples you give only need 5V and 12V. So all you really need is the PC power supply you already have! That and some USB sockets. Why did you think you needed the two fine adjustment potentiometers?
  13. KrisBlueNZ

    Chat_Ghosty's PSU

    The heat dissipation is equal to the output current multiplied by the voltage difference between the INPUT VOLTAGE to the regulator and the OUTPUT VOLTAGE of the regulator. The reference voltage is not a factor. Using different voltages as inputs to a linear regulator would require extra...
  14. KrisBlueNZ

    Chat_Ghosty's PSU

    Correction to my previous post. The input filter capacitor in the power supply is visible in your picture; it's 47 uF at 400V. This would take less than a minute to discharge to a safe voltage with a 56K 5W bleeder resistor across it. I think it's good that you've chosen not to get into...
  15. KrisBlueNZ

    Chat_Ghosty's PSU

    Dave, I understand. I made some general comments as well, and I thought maybe an analysis of that design might be interesting to the OP and useful to others who might browse the thread later. My main comment is that with a linear regulator there will be an issue with heat dissipation...
  16. KrisBlueNZ

    The frequency to make us sleep?

    LOL Raven :-) I'm not sure if you're serious with the shamanic drumming comment, but I agree that rhythmic patterns are more likely to be able to change people's mental state. I'm a musician myself and I've found myself literally starting to fall asleep standing up while "grooving deeply" (I...
  17. KrisBlueNZ

    The frequency to make us sleep?

    I would look at actual research rather than unsubstantiated claims about commercial products. I would also give more credibility to an article that didn't consistently misspell "binaural", the key word in this system! This web site is for people who know about electronics. You need to...
  18. KrisBlueNZ

    Chat_Ghosty's PSU

    You don't need diodes with the chain of resistors. From the feedback point (pin 2 of the LM324) you start with the first resistor, 500 ohms (for 1.5V); at the far end of it, you connect the first position of the rotary switch, and the second resistor, which represents the difference between...
  19. KrisBlueNZ

    Chat_Ghosty's PSU

    There are a number of problems with that schematic. I'd be interested to know where you got it from. The second 9V battery, labelled V3, that provides the -9V rail for pin 11 is not needed because the LM324 is single-supply-compatible - pin 11 can be connected to the ground rail of the circuit...
  20. KrisBlueNZ

    Building a digital clock

    As CocaCola says, an RTC won't drive a display. They just keep track of the time, using a watch crystal and a backup battery, and can be interrogated by software (software running on a microcontroller or processor). Usually a digital clock is implemented using a microcontroller, or a dedicated...
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