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  1. KrisBlueNZ

    rain warning device

    Are you TRYING to be dense? What is the point of climbing up onto the roof to put the sensor where you can't get to it, to check it, to clean pollution and bird crap off it, to remove corrosion, or for any other reason, when putting it on the roof gives NO ADVANTAGES compared to simply putting...
  2. KrisBlueNZ

    Does there exist a relay with 2 inputs that triggers to the input with the lowest V

    Yes, there are various ways to do what you want. First though, can you give some details of your solar charger. 1. What is the maximum charge current? 2. Will there be a problem if one battery is suddenly substituted for another battery, which the charger was previously charging? In other...
  3. KrisBlueNZ

    Voltage amplification?

    Thanks for the rule of thumb and the link, Steve.
  4. KrisBlueNZ

    50 Khz Current amplifier

    What is a HI_WI? OK, you don't know what the project is for. SOMEONE there knows what it's all about, right?. Tell that person that you need to know a lot more about the project, otherwise you can't do anything.
  5. KrisBlueNZ

    50 Khz Current amplifier

    Exactly right Dave. I've seen many threads go on for ten, 20, 30 or more posts before the OP even explains the purpose of the project. It is a complete waste of time, and IMO, an insult to the nice folks here who are just trying to help. In some cases, the OP seems to exhibit some kind of...
  6. KrisBlueNZ

    Proximity Alarm device

    I hope so. I'm interested in this project.
  7. KrisBlueNZ

    Toshiba CRT TV Model 21S1ES- No picture

    Oh, did it?... good... :-/ LOL Sorry, I will not enable JavaScript for that site, because I do not trust it. I will send you my email address so you can send the service manual to me directly.
  8. KrisBlueNZ

    50 Khz Current amplifier

    If you have no idea what the waveform will be used for, it's a waste of time for anyone to try to advise you. This is not some simple "car light delay timer" project! When you use terms like 50 kHz sinewave, 200VA and push-pull converter, you have to be more specific about what you're trying to...
  9. KrisBlueNZ

    MOSFET I-V characteristics using Probe station and Agilent's parameter Analyzer

    Thanks for the thorough description of the problem. That's an interesting project. My guess is you may be getting interference from the N-channel MOSFET. The 4007UB gate contains both the P-channel MOSFET (source connected to pin 14) and the N-channel MOSFET (source connected to pin 7) and...
  10. KrisBlueNZ

    Voltage amplification?

    As Steve says, you need a boost converter. Your comments about transistors amplifying current and FETs amplifying voltage are correct, but amplification relates to signals, which contain just information, and not a significant amount of _energy_ or power. For example, you can use a transistor...
  11. KrisBlueNZ

    Ohm's Law doesn't work - Weird?

    Great thread! And good advice, as usual. This highlights the subject of internal resistances of voltage sources, which are often not understood by newcomers to electronics. Every voltage source has an internal resistance. A PC power supply rated at 30A and 3.3V will have an extremely low...
  12. KrisBlueNZ

    stepping down voltage twice

    Let me guess. This is a circuit to rotate a solar panel to follow the sun, right? And the west and east LDRs are mounted on the solar panel frame, pointing slightly left and right of the panel? Yes, definitely add at least one decoupling capacitor on the output of the 7812. Also I would delete...
  13. KrisBlueNZ

    Type of filter

    Where's the rest of the circuit? It looks a bit like part of a Baxandall circuit but without the rest of it, it's impossible to say.
  14. KrisBlueNZ

    Proximity Alarm device

    That sounds like a very interesting project. I don't recall seeing the thread that relates to it. Is it https://www.electronicspoint.com/remote-distance-sensing-t254967.html about mapping cave profiles? Do you have any documentation on the project so far, that you could share with us?
  15. KrisBlueNZ

    Function Generator

    The LM566 circuit in post #4 is interesting. I had never heard of the LM566. (Not to be confused with the LM556, which is a dual LM555). Apparently it's a voltage-controlled oscillator, but neither Digikey nor Mouser lists it, so I imagine it was discontinued a while back. I don't think you'll...
  16. KrisBlueNZ

    Building a battery-powered charger: feasible project for a beginner?

    I think that's what Mr. Rhythmdvl was suggesting. Whether it's workable or not comes down to the total amount of energy needed. Your charger is rated for 9V and 1.3A so let's assume that you need to provide a 9V supply and that the rechargeable device will draw 1.3A. You say the device charges...
  17. KrisBlueNZ

    please help me

    What current do you want to run through the LEDs? What is the forward voltage of each LED at that current? Do you have a part number for the LEDs so we can view the data sheet? Have you read the LED driving tutorial that Steve mentioned in post #4? His other advice is dead-on as well. If you...
  18. KrisBlueNZ

    rain warning device

    This is to detect rain so the lady can bring in the washing. By the time a tipping bucket rain gauge has tipped, the washing will already be pretty wet!
  19. KrisBlueNZ

    Chargin NIMh 6v 10000mah Battery

    I agree with GreenGiant here. The MAX713 data sheet specifies that the minimum fast-charge rate is C/4 so with a 10 Ah battery, you need to charge at at least 2.5A. The input supply also needs to provide the load current, so it needs to be able to supply at least 4A. From my experience with...
  20. KrisBlueNZ

    50 Khz Current amplifier

    You want to amplify a 50 kHz sinewave and generate a bipolar current proportional to the waveform with peaks of +10A and -10A? And from your comment about 200 VA, you want an output compliance of about +/- 10V? That's quite a project... You can probably use a pair of complementary current...
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