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  1. Alec_t

    Any infos on µA circuits?

    Simulation suggests that if R1 is increased to 1.5 Megohms, the constant current becomes 1μA and the voltage across the sample remains below 1V for all sample resistances up to 1 Megohm. [Note: I don't have a Spice model of the MAX4006. My simulation used the LTspice Universal op-amp2 model, so...
  2. Alec_t

    Little Electronics storage ideas

    Best to keep static-sensitive items in anti-static wrapping until needed.
  3. Alec_t

    Any infos on µA circuits?

    After doing a bit of googling I now think you could use a 3V lithium cell to power a constant-current source. There are micropower 1.25V voltage references available (e.g. LTC6656-1.25) and micropower op-amps (e.g. MAX40006). Something based on the attached circuit might meet your requirements...
  4. Alec_t

    Any infos on µA circuits?

    If all you have to power any proposed circuit is a button cell, I don't see any obvious way of creating a constant current source (albeit only a μA or so) able to maintain the current within a ±1% tolerance.
  5. Alec_t

    Any infos on µA circuits?

    We know you want something in the 0.3μ to 4μ range, but how constant? ±10% tolerance?, ±1%?, ....?
  6. Alec_t

    BC547 transistor

    Thanks Bertus.
  7. Alec_t

    BC547 transistor

    Oops. Can't edit my earlier post. Base current implied is indeed ~ 0.5mA-1mA, and actual is ~0.43mA.
  8. Alec_t

    BC547 transistor

    A red LED drops about 2V, so for the linked circuit the collector current will be a ~(5V-2V)/330Ω = 0.01A = 10mA. For circuit design purposes a bipolar transistor used as a switch is assumed (by a rule of thumb) to have a current gain in the range 10-20. Provided the transistor used has an...
  9. Alec_t

    12v to 24v absolute beginner

    A general-purpose 24V supply doesn't have a high enough voltage to fully charge a 24V battery, nor does it have the necessary features to charge the battery safely. Li-ion batteries need a special charging profile to avoid the risk of fire or explosion ( see here ).
  10. Alec_t

    USB with 5 wires?

    Welcome to EP! I would hope so, after 5 years ! :)
  11. Alec_t

    Question: Is my router repairable?

    The IC at top left of image '358 in post #6?
  12. Alec_t

    Question: Is my router repairable?

    Post #7 has parts missing?
  13. Alec_t

    john deere tachometer

    Welcome to EP! That's not making sense. Please explain.
  14. Alec_t

    I need some experienced peoples advice

    Welcome to EP! You would have to (a) have very deep pockets and (b) buy a DC-to-DC boost converter able to handle something over 14.4kW. What is your budget for this?
  15. Alec_t

    NE555 reset pin using transistor

    That's what should happen, until the sensor is triggered. Sounds like the source of your problem is elsewhere.
  16. Alec_t

    NE555 reset pin using transistor

    In that case Bertus' suggestion (post #18) should work.
  17. Alec_t

    NE555 reset pin using transistor

    When you want your 555 to stay 'off' (pin 3 low), is the sensor output high or low?
  18. Alec_t

    Trying to create a sunrise/sunset power up/down LED strip

    59W dissipated in a sealed enclosure could make things quite toasty, unless your enclosure design provides some heat-sinking, e.g by having a large metallic surface area. 59W is a lot of light. How big is the aquarium? If only a modest size, then the fish will need sunglasses :)
  19. Alec_t

    Trying to create a sunrise/sunset power up/down LED strip

    Welcome to EP! An analogue circuit using discrete components similar to those in the video is totally unsuitable for ramp times more than just a few seconds. A microcontroller or some other digital timer would be the preferred tool for the job. What for? Why would it? Your LED strip requires...
  20. Alec_t

    Fine movement of 12v motor on pan/tilt head

    That may pose a problem if the existing controller does indeed use PWM for speed control. Depending on the controller's characteristics, conflict can arise between any PWM add-on and the controller's own PWM. Do you have a 'scope to check if PWM is currently being used?
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