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  1. KrisBlueNZ

    What wil be the output?

    Right. If R32 is needed, it must be connected BEFORE R27, not after. If the circuit is being controlled by an open collector/drain output, its logic should be reversed, using another inversion stage probably, so that the open collector/drain output is designated active-low. This is standard...
  2. KrisBlueNZ

    Voltage regulator output question

    Hello and welcome to Electronics Point :-) Start by showing us a complete circuit diagram. Do you have a smoothing capacitor after the bridge rectifier? Your answer should be yes.
  3. KrisBlueNZ

    What wil be the output?

    This seems to be a switching circuit to switch a 6.5V DC rail onto a signal called VPP_4 which probably connects to a pin on a programmable device that requires 6.5V as a VPP (programming voltage) supply while it is being reprogrammed. This would be used as part of a device or (E)EPROM...
  4. KrisBlueNZ

    Connect to Home Phone Wirelessly

    It would help to know where you are. There is a field for this in your profile. Here in New Zealand (and also in Australia) there's a company called Uniden that makes cordless phones; they have an "emergency pendant" product that's designed for old or disabled people. Pushing the button on the...
  5. KrisBlueNZ

    Red and green LED's circuit

    What is the power or current rating of the light bulb? Are you using a 12V DC supply?
  6. KrisBlueNZ

    Car sound system conversion to home use.

    solo2racr, that's a good suggestion. He would need a float charger with 13.8V output, and enough current to cover the total quiescent current of the whole system plus a good margin for output power, depending on the typical volume level. BobK, that sounds like good advice.
  7. KrisBlueNZ

    TDA2030A Headphone Amp Gain too high

    That's very interesting. You've obviously done some homework! I had never seen the "diamond buffer" design before, and I'm glad to know about it now. I think it's quite elegant, but I don't know enough about transistor characteristics and audio circuit design to be able to tell you much...
  8. KrisBlueNZ

    Car sound system conversion to home use.

    OK, first, you can't estimate the maximum current drain of each amplifier based on its rated output power, because amplifiers are never 100% efficient. Even 75% efficiency would be pushing it, unless they're class D. Second, if the power supplies you have are rated for 7.5A (or 10A? it's not...
  9. KrisBlueNZ

    SONY TA 313 AMPLIFIER DISTORTION PROBLEM

    Yes, please post a link to the service manual, and when you receive it, check it out thoroughly and tell us the problems you have found. Fault descriptions are often not very accurate.
  10. KrisBlueNZ

    Power supply lost -5 volts

    Follow the -5V wire back to the board and trace the track. It may go to a 7905 regulator as Claas suggested, or it may be supplied from a winding on the main transformer via a diode. Check for broken tracks, dry joints, and broken joints, and VERY CAREFULLY check the pin voltages on the 7905 if...
  11. KrisBlueNZ

    clap based volume control

    Right. If you use a higher supply voltage (12V is better than 10V) and increase the resistance of the resistors in series with the LEDs until the 4017's outputs all exceed 2/3 of the supply voltage when they're high, you will get reliable operation. The LEDs may not be as bright as you want; in...
  12. KrisBlueNZ

    Car sound system conversion to home use.

    Current-sharing between multiple power supplies using diodes is not ideal; it would be better to power different amplifiers from different power supplies instead of merging them together into a single supply rail and powering them all from that. Just keep the negatives commoned. As long as no...
  13. KrisBlueNZ

    dark activated circuit lamp

    . . . .
  14. KrisBlueNZ

    Constant Battery charger

    Electro132, your comments bring to mind the old adage "A little knowledge is a dangerous thing". You have obviously seized on, and misunderstood, ideas that have made you think that you, a beginner, have found a solution to that age-old problem of conservation of energy, and that your brilliant...
  15. KrisBlueNZ

    dark activated circuit lamp

    OK, that's fine. You're using a Cree XP-E white LED that has a forward voltage of around 2.9V at 200 mA. My calculations in post #5 on this thread are applicable. Your series resistor should be about 10 ohms.
  16. KrisBlueNZ

    Design question on microcontroller and TIP122

    Yes. The 8051's port architecture (on all ports except port 0) is called quasi-bidirectional. The digital I/O ports on most microcontrollers have a readable input register, a read/write output register, and a read/write data direction register (DDR) (on PICs, it's called the tri-state register...
  17. KrisBlueNZ

    Design question on microcontroller and TIP122

    Yes, your explanation sounds likely. I'm not sure about your voltage calculations. I don't think you need to make up a test circuit; the arrangement is simple enough.
  18. KrisBlueNZ

    dark activated circuit lamp

    I have no suggestions for projects for your second year of your course. The circuit you linked to cannot provide 200 mA of current for the LED. The BC547 transistor is only rated for 100 mA. My circuit is a lot better - it has a quality called hysteresis (look it up on Wikipedia) which ensures...
  19. KrisBlueNZ

    Looking for recommendations

    Also check your city library for older magazines. I learnt a lot from Everyday Electronics (UK) and Electronics Today International ("ETI") (Australian). No doubt there were many equivalent magazines in the USA as well. Have a look through all the DIY construction projects to see which...
  20. KrisBlueNZ

    40106 output current capability?

    Steve, do you think it's very likely that modern CD400x devices would give better average performance than the original data sheets state because of process improvements?
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