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    PIC A/D sampling help

    Hi I have attached two waveforms that are going into a PIC18F4520 micro A/D pin. The PIC is powered from 3V using the VDD (3V) as the internal reference voltage. Waveform 2 should be easy to measure, it settles at 900mV. I am struggling with waveform 1, which cycles through 1.3V and 800mV...
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    Capacitive reactance affecting voltage divider output

    Hi all I have attached a circuit diagram, which although not complete gives an idea to a issue i am having and trying to find a solution too. I have a sounder element with capacitance of C1 and C2. The total capacitance is 1/c1 + 1/c2 + 1/c3 This works out to 3.47nF. At 4KHz (resonant...
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    Maximum voltage on PIC I/O line

    Hi all I wanted to ask what is the maximum negative and positive voltage i can apply to the PIC I/O line when configured as an input. I think it is VDD + 0.3V and VSS-0.3V The PIC has input protection diodes. So my question is can i go beyond these limits? Say i had 3.6V and -0.6V. Would the...
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    PiC micro I/O line states

    Hi all. I have a voltage divider connected to a PIC I/O line. A pulse comes in at the top of the divider network, scaled downand fed into the PIC. I am inly detecting for a high to low edge usibg interrupts. This happens only once a day for 4ms then off. I am finding that i am getting a current...
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    PIC16F1939 High to low edge detection

    Hi I am using a PIC16F1939 processor. I am using a I/O line as an input to detect a high to low transition then to generate an interrupt on PORTB. I am operating the PIC at 3V. Using a TTL buffer, I see the following information. Looking at the datasheet VIL is 0.15VDD and the conditions are...
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    PiC A/D loading signal

    Hi I have a voltage divider circuit consisting of a 20K at the top and 10K to ground. Centre pin to PIC A/D. The pic is used to measure high to low transitions of a square wave pulse. So the A/D is not used. I am sure my signal is being loaded. Can i add a voltage follower after the voltage...
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    Interfacing a NTC thermistor to a PIC

    Hi I have a NTC thermistor. I want to connect to a PIC (PIC18F4520) A/D for temperature measurements. Is a simple voltage divider circuit good enough? The curve is non linear for the thermistor. Is there anyway of overcoming this in hardware? Or Software. Finally if i use a PTC thermistor are...
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    Checking PIC18F4520 Timer 0 overflow

    Hi I am using MikroC compiler for the PIC18F4520 family. I want to know how I check if TMR0 has overflowed? I have seen on a PIC16xxxx device it is just as TMR0, the following are snippets of code for a PIC16F device :- i.e. TMR0 = 0 /*clear TMR0*/ while (TMR0 < (int) 500/2.048)) How do I...
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    Start up I/O lines of PIC micro

    Hi all, I am writing some code for the PIC18F4520 micro..some of the code is to flash LEDs dependent upon certain conditions. I have set these I/O lines as outputs. I am noticing that on switch on these LEDs are lit, sometimes randomly. Should i make I/O lines as input initially to avoid this...
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    Wanted: Electronics components

    Hi all I am after some electronic components so that i can build some circuits. Looking for resistors, capacitors, transistors, FETs, transformers, LEDs etc. Most will be through-hole so i can prototype on breadboard. Other ghan RS components or Farnell I cant seem to find a good resource which...
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    Serial communications resource for PIC in C

    Hi all I use Mikro C and PIC18F family for my projects. I wanted to ask if there is any good book to teach serial communications with easy to follow examples in C. I am after RS232, RS485, USB, I2C, SPI and one wire examples. The examples need to be easy ti understand and working. Thanks in...
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    Using text editor within MPLAB v 8.92

    Hi All I have MPLAB v8.92, which i usr to prigran PICs in C. I wanted to ask if there is anyway i can use a different text editor to compile via MPLAB, then recompile in MPLAB or even using another compiler. Is that possible? Thanks in advance.
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    Working out required track width

    Hi all I have a question regarding PCB track width. If i have 1oz copper. I have an external EEPROM connected to my PIC micro via I2C interface. How do i obtain the correct track width and length. I have positioned the EEPROM clise to the PIC to minimise track length. I am using Eagle PCB. On...
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    Programming c on raspberry pi

    Hi I am looking to program in c on the raspberry pi 3. It comes installed with NOOBS. Do i need to install anything else to get my c programs up and running ie complier or OS. I am a newbie to the raspberry PI so not sure. Thanks in advance.
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    Eagle v8.3 PCB tutorial

    Hi all I am using Eagle PCB V8.3. I need a good tutorial that covers 1. Creating layers ie 2 or 4 layers 2. How to create keepouts 3. Handling library management especially version control and obsolete parts Thanks in advance
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    Test jig for testing production PCBs

    Hi all I am looking into designing a test jig that will be used to test populated PCBs off a production line. The PCBs will be microcontroller based with I/O lines connected to LEDs, buzzers, some analogue circuitry too. I need to be able to test each PCB circuit functionality using a test rig...
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    Wanted: Practical Analog Electronics for Technicians by W A Kimber

    Hi all, I am trying to get hold of the following 2 books: Practical Analog Electronics for Technicians by W A Kimber Practical Digital Electronics for Technicians by W A Kimber Does anyone have these that they will be willing to sell? Thanks Raj
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    BJT transistor saturation

    Hi all I have a homework question which i would like someone to verify my results please. I have a npn transistor. Rl and Rb are not given. Common emitter configuration. Vcc is 18V. Power is 2W. So using P=VI, transpose this gives me I = P/V = 2/18= 111mA Hfe is IC/IB Note hfe min is 180 Ib is...
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    Removing DC offset

    Hi I have a 9V pulse at 4KHz. This is slighty negative going to about 200mV. I need this fed into a PIC to detect edges. I used a diode to remove the negative oart of the signal. Then fed into a potential divider to divide by a factor of 3. However the output is a square wave sitting on a dc...
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    Wanted: Everyday practical electronics teach in 2002

    Hi I am trying to get copies or pdf copies of the entire EPE Teach In 2002 series. I have tried theire website but cant seem to find these. Does anyone here have copies or know where i can find them from. Thanks
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