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Type: Posts; User: pjmelect

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  1. Replies
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    Closed: Re: HP 54520A Blown Fuse Problem

    I would give the power supply to someone who knows how to fix power supplies. If you want to try and fix it yourself, then from what you have said there maybe no fault with the power supply, rather...
  2. Closed: Re: Need of Equivalent IC for SST89E51RD-40-C-PIE

    You can still buy this chip why do you need the equivalent?
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    Closed: Re: SD card - pull-ups required?

    I have used an SD card without any pull ups. But depending on the micro used this may cause extra current to be drawn when no SD card is present. If in single bit mode (SPI) the three unused SD card...
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    Closed: Re: SD card - pull-ups required?

    The pull-up resistors are for protecting the CMD and the DAT lines against bus floating when no card is inserted. So if the SD card is permanetly fitted, pull-up resistors are not needed.
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    Closed: Re: ATX power supply switch

    On an ATX power supply connecting the PS_ON pin to ground will turn on the power supply, when the PS_ON pin is disconnected from ground the power supply goes off. Logic on the motherboard keeps the...
  6. Closed: Re: How to measure differential signals using an Oscilloscope

    On older oscilloscopes you invert one channel and sum the two channels. One problem with doing this is that the bandwidth is drastically reduced to around 1Mhz depending on the scope.
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    Closed: Re: HP 54520A Blown Fuse Problem

    It is unlikely that that part would cause the problem of the fuse blowing after a minute. It is a inrush suppressor so that after a minute its job is done and no possible fault with it will cause the...
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    Closed: Re: HP 54520A Blown Fuse Problem

    With this type of fault, you will have to reduce the circuit to find the fault. first try removing R13 and R14 and see if the fuse still blows. If not reconect R13 R14 and disconect CR24, and see if...
  9. [SOLVED]Closed: Re: [moved] How to fix Windows 10 Error? (copying files from network drive)

    This error is caused by a corrupt file system either on the networked drive or on the system drive; you should do a system file check on both drives.
    Another possibility is that you are getting...
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    Closed: Re: Low drop voltage regulator

    The AMS1117 has a dropout of 1.1V at 0.8A, at 50mA the dropout is much less.
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    Closed: Re: Low drop voltage regulator

    What about the AMS1117 3.3V ? I as well as many others sell them on eBay for not much money. As wwfeklman said it is important to use the manufacturer’s recommendations as to the input and output...
  12. [AVR]Closed: Re: Proteus: internal Exception: access Violation in module 'UNKNOWN'

    Does your school have a licence for the ATMEG CPU I am assuming that your school has a genuine version of Proteus.
    PIC and ATMEG CPU’s require different licenses which are very expensive.
  13. Closed: Re: I have problem with my proteus 8.4 simulation

    Often this type of error is caused by missing grounds, post your Proteus circuit if you want further help.
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    Closed: Re: Electroncis degree website blocked..why?

    Instead of starting the addres with https: use only http:
    This now works.
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    Closed: Re: input impedance to ADC pin on PIC16F18856

    I disagree, the 470nF capacitor effectively gives an impedance of zero ohms as far as the input to the ADC is concerned, the voltage of the 470nF capacitor voltage is reduced by the charging of the...
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    Closed: Re: input impedance to ADC pin on PIC16F18856

    If the resolution of the A-D is 12 bits then the capacitor needs to be at least 4096 X 5pf to get 1 bit resolution which is just over 20nF I would suggest the use of a 47nF capacitor. As for the...
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    Closed: Re: input impedance to ADC pin on PIC16F18856

    As long as the sampling rate is low enough then what you sugest will be fine. As the sample capacitor is only 5pF 470nF may be more than you need. Don't forget about input leakage though.
  18. Closed: Re: lcd display problem with unclear characters

    The voltage of a LCD is critical if the 5V is down by only a few hundred milivolts can result in no display or very bad contrast on most displays. If you increase the supply voltage you will need a...
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    Closed: Matching transistors 2SA899/2SC1904

    I have a number of 2SA899/2SC1904 transistors that I am going to sell on eBay, I think that they will sell faster and for a better price if I were to sell them as matched pairs. I think that for a...
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    Closed: Re: problem with proteus

    Yes you could tri state one or the other by setting the pin to an input, but how does one chip know when it is safe to put its pin to output, as there is no other communication between the chips. You...
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    Closed: Re: problem with proteus

    Can you connect two txd pins together?
  22. [PIC]Closed: Re: PIC16F877A correct wiring and the external clock?

    You have not defined the configuration bits. Proteus may not care about this, but the hardware does.
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    Closed: Re: AD9851 module function genertor

    You could always buy a pre programed PIC on ebay to drive the AD9851 module, you may find the programming required to calculate the data a bit dificult.
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    Closed: Re: SD card multi block read

    Another funny thing that I have noticed is that I have read the CSD values for 5 different SD cards from different manufacturers and I have got the following values for the access time.

    128MB...
  25. Closed: Re: Is there a safe way to fix this scratch on the hot side of PSU?

    The first picture the track has lifted, I would solder a piece of wire in its place, the third picture the solder joints have burnt due to very high peak currents and the second from the bottom joint...
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