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Type: Posts; User: barry

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  1. Closed: Re: Can someone help me to find out what an unknown PCB is?

    Seriously? Of the millions and millions and millions of electronic products out there, you expect somebody to tell you what that board is? Why? What would you even do with this?

    THROW IT OUT!!!!
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    Closed: Re: Altium - how to map pins to multiple pads?

    i don't see your problem. Pin 7=in; Pin 8= in; Pin 9= in...

    This is done all the time, e.g., FPGAs which have multiple power and ground pins.

    Is your problem with the large copper pad? Just add...
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    Closed: Re: Bridge Rectifier won't Rectify

    Maybe you should tell us what we’re looking at. Maybe you should tell us what your input is. Maybe you should post a schematic.
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    Closed: Re: STM32F3 built-in opertion amplifier

    I pretty much disagree with everything you said. The minimum load resistance IS NOT a function of voltage. It probably has something to do with compensation.

    If you're evaluating accuracy,...
  5. Closed: Re: How to build overcurrent/overvoltage protection

    More information is needed. Voltage? Current? Showing two blocks with lines between them tells us nothing.
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    Closed: Re: STM32F3 built-in opertion amplifier

    Those are two separate specs. There’s nothing that says you can drive 2.5 volts into 4K. It says you can have a minimum load of 4K, but your application has to limit the current to 500uA. If you use...
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    Closed: Re: circuit design help analog to Potentiometer

    As Brian notes, it's a pretty simple matter to just replace the pot with an analog voltage. There is nothing in the pot circuit that has anything to do with "detecting issues".
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    Closed: Re: Decoupling CAP using MOSFET?

    Huh? Why on earth are you using a MOSFET for a decoupling cap????? Why not use, um, a CAP?

    But assuming for some bizarre reason the only components you have are MOSFETs, you have to be aware of...
  9. Closed: Re: Keypad playing sounds - Recommendation for design

    Questions for you:

    1) what kind of “sounds”do you want this to make? You don’t need MP3 to make beeps.
    2) How long do you want the battery to last? THAT will determine the size.
    3) do you want...
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    Closed: Re: controller not wark proper in power on

    Just telling us “they don’t work” is meaningless. Do they explode? Do they make strange noises? Give us SOMETHING. Maybe it’s your reset circuit. Maybe not.
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    Closed: Re: circuit design help analog to Potentiometer

    You mean the welder CONTROL voltage is 0-6.2? It’s still unclear what you’ve got going on here. Saying “it monitors all three connections” is doubtful. And what “issues” could it possibly detect from...
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    Closed: Re: circuit design help analog to Potentiometer

    I’d use a small microprocessor and a digital pot. They do make motorized pots that can be controlled by an analog voltage, but they are big and expensive. You could also use a servo, but then you’d...
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    Closed: Re: circuit design help analog to Potentiometer

    Not sure what you’re talking about: “send 0-6.2 V through a potentiometer”, but then you say the welder is “monitoring all three connections...” . Do you want an analog voltage to control a pot? Do...
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    Closed: Re: Wrong sinusoidal signal

    Vertical gain
  15. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    PWM is waaaaaaay overkill. You can accomplish the same function with a parallel resistor and cap driving the relay.
  16. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    SSRs don’t draw anywhere near 47mA. You make no mention of what your load current is, which will dictate the coil current. Reed relays draw about 10 mA.
  17. Closed: Re: How to use the same RELAY on 12V & 24V vehicles

    Why not use a regulator, or even a zener, to drive the relay?

    Or, a little more complicated and a little less reliable, have the MCU monitor the input voltage and select one of two transistors to...
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    Closed: Re: Estimated cost of high volume PCB assembly

    I think there are just too many factors to give you a "rule of thumb". You also have to consider: pin pitch; number of components; standards; etc. Also. testing is not priced "per hour", it's per...
  19. Closed: Re: This is a simple capacitor or it has a resistor inside it?

    It says right there that it's .25uF 630V. But it shouldn't read 30 ohm. HPF is probably just a manufacturer's number. Throw it away and buy a new one.

    Just a thought: are you waiting a few...
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    Closed: Re: Capacitive Effect on Tracks

    What on earth is an “nrf”?? National Retail Federation?

    When you post a question here don’t assume everyone knows your arcane abbreviations.
  21. Closed: Re: What does "great linearity" means for a ring oscillator?

    I

    Sorry to disagree, but a sinusoid is a transcendental function, NOT a linear function. The linear response of an amplifier means if you plot the output versus the input you’d have a straight...
  22. Closed: Re: What does "great linearity" means for a ring oscillator?

    The deviation of a sinusoidal signal from the ideal has nothing to do with linearity. A sine wave IS nonlinear! Maybe this is a language problem.
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    Closed: Re: What dc can u measure?

    Obviously OP is going to take all the answers and average them.
  24. Closed: Re: What does "great linearity" means for a ring oscillator?

    If you're using a voltage to control the oscillating frequency then the linearity is the relationship of voltage to frequency. In other words, if you plotted voltage on the x-axis and frequency on...
  25. Closed: Re: What is the Max RMS System Noise before 'hiss' is can be heard in Headphones.

    You already admitted that this is pretty subjective, so there really is no answer. But, nominally, the minimum detectable level is 0 dBm SPL. This is related to air pressure. How this relates to your...
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