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  1. KrisBlueNZ

    Designing a Time Delayed Relay

    You mean you're concerned that there won't be enough PCB area for the components? My gut feeling is that 8.2 x 8.2 cm will be big enough, but I'll have to check. Can't work on it right now though.
  2. KrisBlueNZ

    Designing a Time Delayed Relay

    I don't know. What are the maximum allowable PCB dimensions?
  3. KrisBlueNZ

    Sony DA555ES "PROTECTOR" message !!HELP!!

    If you suddenly turn the volume up to maximum, does the PROTECT error occur immediately?
  4. KrisBlueNZ

    Midi File Sounds

    As Gryd3 says, MIDI is a data protocol that doesn't contain audio. To convert it to audio, you need a MIDI synthesiser of some kind, which either generates sounds using analogue (or simulated analogue) techniques like FM, or triggers playback of stored sound samples. A stored sound sample is...
  5. KrisBlueNZ

    Designing a Time Delayed Relay

    I think that would be OK if you use a standoff between the heatsink and the PCB. Either nylon or metal. Or could you mount it on the underside of the PCB? Either with a short standoff, or flat against the board if you can avoid tracks on the underside in that area.
  6. KrisBlueNZ

    Basic Electronics kit

    For general low-power applications, metal film 1% resistors are normally used even when 1% accuracy isn't needed because they're pretty cheap and it's not worth keeping stock of more than one type. The only place I've seen carbon 5% resistors used nowadays is in cheap Chinese products, where...
  7. KrisBlueNZ

    Need help with Fan Speed Control

    Sounds like PWM is the answer, as mentioned in this thread: https://www.electronicspoint.com/threads/need-help-desiging-kick-start-for-a-fan.269583/
  8. KrisBlueNZ

    Need help desiging "kick start" for a fan

    You could try connecting this circuit onto your PWM controller. It pulls pins 2 and 6 of the 555 low for a short time after power-up, forcing pin 3 high and turning the transistor ON steadily for a short time. Increase the capacitor value for a longer kick-start time.
  9. KrisBlueNZ

    Repairs to fog machine

    Sorry, I didn't read your question properly. I think it's quite possible that a pump could be faulty in a way that causes it to barely run at all when powered from a phase controlled signal at, say, 50% power, while it would still run at full speed if powered from a 100% AC signal. So if a...
  10. KrisBlueNZ

    Designing a Time Delayed Relay

    Yeah, with AC, capacitors and inductors do some pretty funky things! Yes, fair enough. TIP29B or TIP29C will be fine. (The suffix indicates the maximum collector-emitter voltage.) Yes, I would say that's a problem. Heatsinks are supposed to be mounted so air flows along the surfaces of the...
  11. KrisBlueNZ

    Resistance of dark solar panel

    Right, that's good. Yes, you can just connect them all in series.
  12. KrisBlueNZ

    [woo] Does anyone know of this breakthrough technology ?

    Done
  13. KrisBlueNZ

    Repairs to fog machine

    You're assuming that when the board wants to run the pump at its standard speed, it feeds the full-cycle 110VAC into it, so if the pump works on 110VAC it should run at the same speed when powered from the board, when you press the Manual button. I suspect the board's standard drive to the pump...
  14. KrisBlueNZ

    Need help with Fan Speed Control

    Whether you use diodes or resistors, the same amount of heat will be generated. Diodes just give you better control of the amount of voltage dropped. A 12V 80W fan will draw 6.7A at 12V. At lower voltages it will draw less current. What voltages do you need to provide to your fan? If you need...
  15. KrisBlueNZ

    [woo] Does anyone know of this breakthrough technology ?

    This "Kings Saver" card is an interesting new application of an old technique called "baffle 'em with bull":
  16. KrisBlueNZ

    7 segment display and CMOS

    http://www.google.com/search?q=connect+rotary+encoder+to+arduino
  17. KrisBlueNZ

    Basic Electronics kit

    Yes, probably, if you can get a kit with, say, two or five resistors of each E12 or E24 value, that's not too expensive, that's probably a good idea. I tend to use certain values much more often than others - I prefer the 10 and 33 values in each decade, and the most common values I use are 10k...
  18. KrisBlueNZ

    Constant current power supply

    Thanks chopnhack :-) Really it's pretty conventional. I grounded the pins of the unused op-amp just to stop them picking up noise. For CMOS ICs it is important to connect unused inputs to something, but not really for op-amps. It does avoid one track cut on the stripboard though (between pin 4...
  19. KrisBlueNZ

    Repairing an oven circuit board

    What are the markings on the TO-220 device? (The three-lead device standing up.) What are the markings on the diode (black cylindrical thing with silver or white stripe on it) that's standing up just in front of it? What is the component that's hidden behind the big resistor? Can you clean...
  20. KrisBlueNZ

    My first circuit, some questions..

    Trickle-charging from a fixed voltage through a resistor is OK, but when power is restored after an outage when the battery has discharged, the charge current will not be controlled and the transistor will overheat unless heavily heatsinked. It's better to regulate the current, to reduce the...
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