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Type: Posts; User: betwixt

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  1. Closed: Re: Car battery STARTER voltage help (not charger) using variety of methods (possibly

    Burned out ignition switches is almost unheard of. What model of car is this?

    Brian.
  2. Closed: Re: Car battery STARTER voltage help (not charger) using variety of methods (possibly

    You are confusing the current paths. Cranking speed is decided by the power available to turn the starter motor and the load imposed on it by the engine. It has nothing whatsoever to do with the...
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    Closed: Re: Dual Power supply from AC input

    It would be if you turned both the rectifiers the other way around.

    Brian.
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    Closed: Re: tda2030 amplifies noise

    My point was that 12V at 1A means a power consumption of 12W (Watts = Volts * Amps) but it claimed 20W output power - so where did the extra 10W come from...

    The audio frequencies you are...
  5. Closed: Re: Car battery STARTER voltage help (not charger) using variety of methods (possibly

    Failure to start at first engine rotation is probably more to do with fuel reaching the cylinders than cranking power.
    FYI, cranking a cold engine (even a warm one) can use several hundred Amps...
  6. Closed: Re: Capacitor Burning issue due to unusual reasons

    (15V - 1.6V)/12000 = 0.0011A so all 8 LEDs turned on at once will pass ~9mA and combined power dissipation of all LEDs and their series resistors will be about 0.13W, barely warm enough to notice. If...
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    Closed: Re: tda2030 amplifies noise

    Ferrite beads will have almost no effect at low frequencies, they don't really do anything useful until 100s of KHz and higher.

    I'm not sure where this fantasy about resistor noise comes from. The...
  8. Closed: Re: Every few Hours clock running fast rtc1307

    Do what Klaus suggests first.
    If it is just the clock running fast, the problem is the crystal (or external clock if you are using one) is too high in frequency. That could be because of the crystal...
  9. Closed: Re: Capacitor Burning issue due to unusual reasons

    My point about LED PIV is this:

    If the solenoid is ON, the output pins of the 2803 will be close to zero and about (VCC -Vf)/470k = 7uA of LED current will flow. (not really enough to be visible)...
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    Closed: Re: tda2030 amplifies noise

    I agree with Audioguru, tube amps were good but like all technologies, they get superseded with something better. Anything that is 'latest technology' is best, but only until technology moves on.
    ...
  11. Closed: Re: Capacitor Burning issue due to unusual reasons

    470K resistors in series with the LEDs will make them seriously dim! The PIV rating of the LEDs will almost certainly be exceeded with 7V (or is it 10V?) across them when the solenoid is turned off....
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    Closed: Re: Dual Power supply from AC input

    The circuit will be unreliable because ground will move according to the difference in load current on the two outputs.

    A better solution is to connect one side of the AC input to ground and the...
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    Closed: Re: tda2030 amplifies noise

    Most of the problems were due to under-rated power supplies. You have to remember that in the 1980's consumer electronics boom, the markets were flooded with very low quality equipment that boasted...
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    Closed: Re: tda2030 amplifies noise

    I have some in stock but they have been collecting dust for 30 years. The last time I saw one in a commercial product was probably in the mid 1980s, they were commonly used in low cost domestic "Hi...
  15. Closed: Re: Capacitor Burning issue due to unusual reasons

    Sorry, my fingers and brain had a faulty data link. I meant any applied voltage up to the rated voltage should not cause problems. It follows that your 25V rated capacitor should be quite safe with...
  16. Closed: Re: Do you know what is likelihood of occurrence of tolerance extremes of L6564?

    For a test result distribution you would have to contact the manufacturer but I would imagine they specify slightly wide of all expected results.
    I've never had any problems using that device.
    ...
  17. Closed: Re: Capacitor Burning issue due to unusual reasons

    1.5 times the applied voltage is good but anything higher than supply should not burn out. I suspect the problem is due to the combined voltage of several solenoids switching off at once. The...
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    Closed: Re: tda2030 amplifies noise

    The capacitor is just to roll off the high frequency response, there is no point in making it adjustable. If you are getting a continuous tone out of the amplifier (post #5) it implies it is...
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    Closed: Re: Energy harvest circuit questions

    To put the energy harvesting in perspective Shanmei, There is a 5kW transmitter about 4Km away from me here transmitting on 880KHz. With a 50m long wire antenna and a good Earth connection I can get...
  20. [PIC]Closed: Re: Need urgent help in switch case in this menu code.

    It is your choice but I find the code confusing, I would do it differently:
    Instead of writing everything "in-line", put the text and the output commands into an array. This lets you select them by...
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    Closed: Re: Electroncis degree website blocked..why?

    Works for me, also in the UK.

    I'm using Firefox 67.03 in Linux.

    Maybe something your computer or ISP is blocking....

    Brian.
  22. Closed: Re: how to make DP flash every sec in 2-digit 7-segments without separation of track

    The PCB only shows one digit. It is how more than one digit is multiplexed that we need to know. Please show us a schematic.

    Brian.
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    Closed: Re: Energy harvest circuit questions

    Crystal receiver at 1GHz ??? :???:

    Brian.
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    Closed: Re: tda2030 amplifies noise

    The tone implies you have instability. I last used those devices in the 1980s and I can remember them being difficult to keep stable. They are not particularly good devices. Try removing the two...
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    Closed: Re: Tip41c/42c arrangement problem

    Even with FETs a bipolar NE555 would struggle to produce enough gate current, I doubt a CMOS one would manage at all.
    The push-pull concept is why I queried whether a center tapped transformer was...
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