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  1. KrisBlueNZ

    need advice/help on dual laptop psu mod (load balancing)

    Have you checked the capabilitiy of the switching supplies inside the laptop? The 19.5V supply into the laptop is converted to lower voltages (e.g. 3.3V and lower) to run the components inside the laptop. The circuits that do this conversion will have maximum current limits as well. If you...
  2. KrisBlueNZ

    Need help with 555 timer circuit

    OK, good. That sounds cool! Positive rail of the breadboard, coming from the power supply. When the MOSFET is conducting, the current will flow from the positive terminal of the power supply, through the paralleled array of LEDs, into the drain of the MOSFET, through the MOSFET and out the...
  3. KrisBlueNZ

    Battery charger monitor

    You can upload the photos to a photo hosting web site and put links in your post. Or you can upload them to the Electronics Point forum, as long as each picture is smaller than about 100 kilobytes. Click "Go Advanced", and click the paper clip icon. Browse and select the pictures, and click...
  4. KrisBlueNZ

    Need help with 555 timer circuit

    No. It will give you more voltage across the series string, so the resistor will drop more voltage, which makes the LED current less dependent on the accuracy of the supply voltage. Yes, except that "voltage draw" is not a concept. Here's an easy way to imagine it. Imagine each LED is a...
  5. KrisBlueNZ

    Need help with 555 timer circuit

    Ah, sorry. In that case, either way is fine. If you're powering the LEDs directly from the 555 (and I think you probably can), you may find that the 555 will pull low more strongly than it pulls high. In other words, if you connect your LEDs from V+ to the output, they may see more of your 9V...
  6. KrisBlueNZ

    circuit modification

    Hello...? What's happening with this project?
  7. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    The proper value depends on the voltage across the resistor, which depends on the forward voltage of the LED, which depends on the colour and type. Find out the forward voltage of each LED, subtract that from 3.7, and calculate the resistance using Ohm's Law, R = V / I where V is the remaining...
  8. KrisBlueNZ

    Need help with 555 timer circuit

    He needs the LEDs to be ON when the 555's output is LOW, so he'll need a PNP, or a P-channel MOSFET. To the OP. You can probably do what you want with just the 555 if you put two or more LEDs in series for each string. You need to find out the approximate forward voltages of the LEDs you're...
  9. KrisBlueNZ

    Rectifier circuit diagram explanation

    OK I'll explain it generally. For more information, google the words that I've marked between '#' symbols. AC mains supply voltage enters through the mains socket. L1101 is a #common-mode noise rejection choke# for #electromagnetic compatibility#. The mains transformer has a #centre-tapped...
  10. KrisBlueNZ

    need help with simple 3v to 34v transistor relay/switch

    The LED that's connected straight across the supply voltage going into the boost converter will be damaged if it doesn't have a series resistor. Not by spikes of current; just by the heavy current that will flow when you try to apply 3.7V across a LED with a forward voltage of 2~3V. LEDs are...
  11. KrisBlueNZ

    Battery charger monitor

    I guess you mean LM358P? This is a very common dual op-amp that should be available from most electronic component shops for less than a quid. Or you can order it from Farnell / Element 14 or RS Components. You can just replace it on suspicion, or take some photos of all the boards and we can...
  12. KrisBlueNZ

    FOG MACHINE PCB FAULTY

    You should be able to trace the tracks from the two 110VAC output connectors back to the relays, to find out which relay switches the heater and which relay switches the pump. It seems likely that the heater is switched by the relay closest to the edge of the board. The two pins at the top end...
  13. KrisBlueNZ

    What to do with 0.5 V and 25 mA?

    That's a good question. The fundamental problem is that 0.5V is not enough for most circuits to make any use of. Linear Technology have developed some ICs that are specifically designed to operate from extremely low voltages. Some of them might be of use to you. See...
  14. KrisBlueNZ

    Woo-Woo OVERUNITY??? you do the math

    I feel no obligation to learn "everything there is to know", and no inclination to waste my time trying to achieve the impossible. I'm happy with quoting the axiom that energy can neither be created nor destroyed; it can only be converted from one form to another. I also will not be responding...
  15. KrisBlueNZ

    Woo-Woo OVERUNITY??? you do the math

    I thought that was because Steve changed the link...?
  16. KrisBlueNZ

    How to address a moderator

    Hey, I already brown-nose Steve plenty! Partly that, and partly I just wanted to share in everyone else's righteous indignation :-) LOL! No comment. Steve forwarded the posts in question to me, so I'm happy now that I've "tsk tsk"ed in sympathy. Now that the guy is banned, I guess he can go...
  17. KrisBlueNZ

    Woo-Woo OVERUNITY??? you do the math

    No, you're not. You're very close to wasting more time and effort on a futile endeavour. Unless your intention is to convince uneducated folks that you're onto something and that they should invest in your design so they can take a cut of the huge profits you'll be making when you're selling...
  18. KrisBlueNZ

    Need guidance; newbie project - LED controllable steps

    You don't really need a microcontroller. If you want to avoid one, you could use an LED dot-graph IC like an LM3914. Or is it the 3915? Whichever one has a linear response. (For 12 steps, you'd actually need two of them.) The control voltage would be selected according switches connected to a...
  19. KrisBlueNZ

    Buzzer to stop my motorbike battery running flat.

    Do a Google image search for Yamaha Fazer 600 wiring diagram. There are lots of hits. Find one that you think matches your bike, and trace the supply voltage from the battery through the ignition key switch, and try to find the matching point on your bike. As Steve suggested, it's probably...
  20. KrisBlueNZ

    Battery charger monitor

    Does the LED display show the battery terminal voltage or simply the timed progress through the charge cycle? Take it apart and take some photos of the board that drives the LEDs. Or if the LEDs are on the main board, take some photos of that. What are the symptoms? I guess the LEDs don't...
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