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  1. (*steve*)

    Woo-Woo Is it possible to attenuate a signal not at the source

    Aside from the fact that repeaters exist to amplify signals... You have been given some suitable answers. And I'll add another... Wrap yourself in mu-metal. I have a bridge for sale. It's really cheap. A great investment.
  2. (*steve*)

    do parallel connected leds consume more power?

    I agree. The LEDs (properly driven) will consume the same amount of power no matter how you connect them. It's the rest of the circuit that you need to look closely at. For a given voltage power supply, and if you use only linear elements to set the current through the LEDs, then a series...
  3. (*steve*)

    Just learning and confused what this resistor does

    The 50k resistor and the LDR together form a voltage divider. The voltage at the junction of these two devices goes up in darkness, and down when illuminated.
  4. (*steve*)

    Beginner question : 555 timer pin 4

    Something with an open collector output cannot go high at all unless there is a pull up resistor -- the output can only pull down. The lower the value of the pull-up, the harder it is for the comparator to pull down, so the higher the "low" output is. So, a higher value allows it to pull...
  5. (*steve*)

    Beginner question : 555 timer pin 4

    If you look at the output of a comparator like that, a pull up resistor is required. I would probably use a pull-up of 10k.
  6. (*steve*)

    Beginner question : 555 timer pin 4

    That value will be defined for a particular pull up resistor value, possibly 2k. If you use a larger value resistor the comparator will probably pull the output lower. You could also use a rail to rail op amp in this application as you're not concerned with speed.
  7. (*steve*)

    Component Identification

    In SOT-23, 2x could mean devices including KST4401, MMBT4401, SO4401, or TMPT4401. All are non silicon transistors rated at 60V and 600mA. Likewise 2T, if it is a transistor is a similar variety of 40V 600mA silicon pnp transistors with the numeric part of their part number being 4403
  8. (*steve*)

    Woo-Woo Is it possible to attenuate a signal not at the source

    Faraday cage?
  9. (*steve*)

    Beginner question : 555 timer pin 4

    I would go for the use of pin 4. It would be better to switch pin 4 using something that has a fast (faster) rise and fall time, and one where the transition point (and hysteresis) can be controlled. You could use a comparator with a little bit of positive feedback to ensure a definite...
  10. (*steve*)

    Beginner question : 555 timer pin 4

    Pin 4 is generally used with a signal which rapidly transitions. In my earlier answer regarding the voltage at which it transitions I omitted a warning about it acting odd during the transition (I've not seen this behaviour, but I'm not surprised by it either). Another thing is that after...
  11. (*steve*)

    Beginner question : 555 timer pin 4

    Yeah, that 1k 0.5W trimmer can pass 22mA without dissipating too much power (presumably at 25C). So 1.2mA will be fine, even at quite elevated temperatures.
  12. (*steve*)

    Beginner question : 555 timer pin 4

    Hahaha. Glad you're still with us. No, that's what it's for. You will find that as the voltage transitions between about 0.4V and 1V that the timer starts somewhere in there, at a point that might even change a little with temperature. You can't guarantee it will be 0.8V.
  13. (*steve*)

    Buck or boost for charging a battery

    The key point is "inverting". This allows you to do buck or boost with a very simple topology.
  14. (*steve*)

    Capacitor tester in circuit

    Well, that makes more sense. I had assumed you were using a multimeter.
  15. (*steve*)

    Capacitor tester in circuit

    How can it output 10V when the power supply is 9V?
  16. (*steve*)

    Acer Aspire 4310 laptop power shut off after 2 seconds

    That sounds like a reasonable suggestion. Normally, a dead battery simply won't charge, but it's possible that yours has a fault which pulls down the power supply and causes a rapid shutdown.
  17. (*steve*)

    Buck or boost for charging a battery

    If you use a flyback inverting topology it won't matter if the panel voltage is higher or lower than the battery voltage.
  18. (*steve*)

    maximize efficiency of a solar panel charging a Li-Ion battery

    Then get another cell.
  19. (*steve*)

    Capacitor tester in circuit

    First issue: I'm talking about your other capacitance meter. It shows you measuring a 4700uF capacitor on it's 20,000 uF range and reading 425uF on it's digital readout. This cap must be faulty and isn't a good unit to use to compare with your meter. Second issue: when set to your 1000uF...
  20. (*steve*)

    maximize efficiency of a solar panel charging a Li-Ion battery

    No, a cell like that, even if it is protected, will charge even at low currents.
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