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Type: Posts; User: betwixt

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    Closed: Re: mplab 8.92 compilation error

    OSCCAL only adjusts the oscillator slightly and it won't stop your code running even with silly values in it. If you are seeing a misbehaving program, other than something very critical of timing,...
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    Closed: Re: C code for PIC16F1508 with ADC

    I would update to v2.10, it may have corrections or better support for that device. As far as I know, just updating/replacing the compiler with the new one will work, I think they are backwards...
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    Closed: Re: Portable headphone amp w. batteries

    Look closely at the power supply schematic - the '0' of the 15-0-15 is connected to the ground point. It has half wave rectifiers to the positive and to the negative rails and then a 1.5A rated...
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    Closed: Re: C code for PIC16F1508 with ADC

    For PWM you need one timer (TMR2) to provide the start time for each pulse but you do not need any interrupts. Basically it works by clocking a counter and comparing the count value with the value...
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    Closed: Re: C code for PIC16F1508 with ADC

    Do you really want to check the ADC output is > 10? By left justifying the ADC result and using ADRESH you are ignoring the two least significant bits. If the value to check is 10, right justify it...
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    Closed: Re: Portable headphone amp w. batteries

    The virtual ground or supply mid-rail must be there, otherwise that point in the circuit will float according to the current drawn by each half of each channel. It is the reference for all other...
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    Closed: Re: mplab 8.92 compilation error

    Sounds like something has reformatted the source code. MPLAB reserves the first location on a line for labels and needs at least one space before an opcode.

    Brian.
  8. Closed: Re: Dimming the MP2489 right down to zero (Buck LED driver)

    I don't understand - if you use PWM you can take it down to zero or any step up to full brightness.

    I think the references to 1.25V are because that is the internal reference voltage. I would...
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    Closed: Re: Portable headphone amp w. batteries

    You have to understand that the output of each channel is a voltage referenced to the zero voltage (virtual ground) point. All the output current from both channels therefore has to flow to/from...
  10. Closed: Re: Dimming the MP2489 right down to zero (Buck LED driver)

    I don't read it that way. That device has analog dimming with the level set by the voltage on the EN/DIM pin. Read 'EN' as digital enable and 'DIM' as the analog voltage but you would normally use...
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    Closed: Re: Portable headphone amp w. batteries

    You should keep C309 and C310 as they are but remove everything before them.

    The bass will indeed roll off at very low frequencies but I doubt you would notice it. The compromise is between good...
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    Closed: Re: Portable headphone amp w. batteries

    1. about 13mA plus backwards leakage in the regulators (= small) will flow back to the PSU so it would be best to remove the regulators and the voltage setting resistors R305 to R308.
    2. you can...
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    [PIC]Closed: Re: lcd interfacing with pic 16f877a

    If the LCD only has 4 data lines connected to the PIC it is a 4-bit interface, if it has 8 data lines connected it is an 8-bit interface.
    Note that the commands and characters are always 8-bit, if...
  14. Closed: Re: Beckman Industrial 9020 - Poor focus with no adjustment

    To some of us those are quite low voltages, only 2KV!

    Seriously, switch it off first and give it a minute or two to discharge capacitors then just start measuring resistances. Download the...
  15. Closed: Re: Beckman Industrial 9020 - Poor focus with no adjustment

    You almost certainly have an open circuit resistor somewhere around the CRT controls. Excessive brightness may also cause the focus defect, it may be pushing the CRT so hard that it can't actually...
  16. Closed: Re: Measuring current with ESP32 and Seeed board

    I think you probably want full scale reading to be 3.3V, not 5V as you will not be able to measure greater than 3.3V anyway. However, a more fundamental problem is the voltage from the transformer...
  17. Closed: Re: Measuring current with ESP32 and Seeed board

    If I understand the original post - the MEASUREMENT is for the load current range up to about 5A but the load may have a brief surge much higher than that and you don't want the surge measurement to...
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    Closed: Re: Change colors of liquid crystal display

    I'm getting confused.
    Are you trying to produce different hues by rotating the polarizer? You may be able to adjust the shading a little - with the risk of 'over shoot' or 'over lap' of fully on...
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    Closed: Re: TCM3105 modem modes please explain

    From the data sheet:
    which implies it has an analog frequency discriminator. That means it cannot distinguish signals between two simultaneous signals in the same frequency range so either the...
  20. Closed: Re: Dimming the MP2489 right down to zero (Buck LED driver)

    If I understand the data sheet, the input is always analog but the voltage range is limited to the internal Vref. It gives you the option of controlling output current by dropping the enable voltage...
  21. Closed: Re: Multiplexing problem in my 8051 clock project.

    I think that should win a prize for the most convoluted and un-commented code ever written to do a simple task.
    When writing a program like that you should first look at the individual tasks it has...
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    Closed: Re: analog pressure gauge to 4 to 20mA

    We have no idea what size the pressure gauge is but if we assume it is a standard rotary type with a moving pointer, my approach would be to remove the pointer and replace it with a transparent...
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    Closed: Re: transistor selection help question

    The data sheet for the 2N4401 says it should typically drop 0.75V between collector and emitter pins when passing 500mA but you need to give it 50mA base current for it to achieve that.
    However, the...
  24. Closed: Re: Operating four Tx-Rx pairs in close proximity

    I use sequential addressable transmitters with active time of only a few mS, faster than a HT12 can send a single code. Given their close proximities, especially the transmitters it would make more...
  25. [SOLVED]Closed: Re: PIC16F877A controlled 74HC595 by serial command

    I cannot use Proteus but looking at the code it seems you overflow the receive buffer after a few characters have arrived fro the USART.
    You use
    char buf[]={0x00,0x00,0x00,0x00}; ......

    ...
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