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  1. foTONICS

    entering the job market

    Hey guys/gals, So one of my biggest interests upon going to school for electronics engineering (2 year diploma) was the microcontroller programming. I read, practice, and experiment it at home as a hobby as well. My question is how hard would it be to get a job as a hardware programmer? I...
  2. foTONICS

    resetting timer0 interrupt flag

    So I was reading up on embedded C programming for the PIC and came across this code that uses the overflow flag of timer0 to trigger an interrupt. But don't you need to clear the flag before you exit the ISR, or does the compiler insert that bit of code by itself? I've attached a screenshot...
  3. foTONICS

    c syntax for PIC's

    So I was reading through "Gooligum's" website and he uses these commands: sGPIO |= 1<<1; // turn on LED on GP1 sGPIO &= ~(1<<1); //turn off LED on GP1 sGPIO ^= 1<<2; //toggle LED on GP2 using shadow reg Now I understand everything but the "|=" and the "&="...
  4. foTONICS

    switch debouncing

    Hey all, I was checking out Gooligum's tutorials and came across this C code for switch debouncing: for (db_cnt = 0; db_cnt < 10; ) { _delay_ms(1); if (GPIObits.GP3 == 0) db_cnt++; else db_cnt = 0; } I understand how it all works but once...
  5. foTONICS

    high side driver

    Hey guys, So with a little help and research I came up with this circuit but Q2 keeps getting really hot. I've made sure at least one of the control signals is always high so I was wondering if anyone could give a little constructive criticism towards it, -thanks for all the help
  6. foTONICS

    Driving a 12v DC motor

    So I was trying to build an hbridge for a 12v dc motor using 2n3055's and was having issues so I decided to break it in pieces and do some testing. Attached is the circuit I tried and it doesn't do anything. Someone told me that I need a high side driver to get it to work. Am I right when I...
  7. foTONICS

    stepping down voltage twice

    So I wired a 7812 and a 7805 in series with the input to the 7805 connected to the output of the 7812. I was expecting 12V and 5V respectively but I got instead 11V and 5V. what happened to that extra volt? I supplied the 7812 with 15V (even brought it up to 20V same issue). I'm aware of the...
  8. foTONICS

    l293 motor driver

    The datasheet says the motor logic inputs are TTL compatible. I was playing around with a prototype and accidently wired it up as 0 and 12 V instead of 0 and 5 but the circuit behaved as expected. can this chip handle 12V on its input pin or will it become damaged after a while? I can't find...
  9. foTONICS

    identifying this terminal block

    Hey all, I'm building this board and I want to use up some spare parts I had from some harvested pcb's. I have this terminal block that I want to incorporate into an eagle drawing but it doesn't have a part number and since I'm new to eagle I'm having a hard time deciding which one it could be...
  10. foTONICS

    Powering a solar tracker

    So I am working on this solar tracker circuit for my final project (I posted on here a couple weeks ago asking for help regarding a couple of things). I want this thing to power itself without relying on any type of battery system, what kind of erratic behaviour can I expect as the sun starts...
  11. foTONICS

    diy logic probe

    I was working on my own logic probe design that met the following conditions: 1. run off 5V 2. Each logic level (high, low, inalid) will have its own LED 3. No LED should light if the probe does not touch anything I have attached a few sketches that I drew up, I'm open to input and the...
  12. foTONICS

    solar tracker

    Hey all, So I wanted to design a solar tracker for my final project and found this very helpful schematic online. I understand almost all of it except for a few things. 1. Why the feedback loop on IC1a and IC1c, is it some sort of gain control? and why would it need to be tied to 9 volts...
  13. foTONICS

    VHDL

    So I've been given an assignment to create a 4-bit parallel load, serial in/serial out shift register. Here is what I have so far: So my idea was that during a HIGH "w_s" signal my data would shift right by this code: and during a LOW signal it would run this code: When I run the code...
  14. foTONICS

    connecing a PICkit 2 => PIC24EP128GP

    Looking up the schematic for the PICkit 2 I have: pin 1: Vpp/MCLR pin 2: Vdd Target pin 3: Vss (ground) pin 4: ISCPDAT/PGD pin 5: ISCPCLK/PGC pin 6: AUXILIARY and looking at the datasheet for the PIC24 I have the corresponding pins: pin 1: MCLR pin 13: Vdd pin 19: Vss the next...
  15. foTONICS

    Searching for a PIC dev board

    Hey all, So I'm searching for a dev board to enhance my studies while at school. I've done a little searching but nothing really comes up that seems right. I'm a bit of a PIC fanboy, I want some LED's attached to the board so I can see if a program works, and I want to code in assembly. Ones...
  16. foTONICS

    Duncan amps PSU designer

    I'm working on this assignment where I need to use Duncan's PSU II designer to model a supply but I'm having a little trouble understanding the purpose of RL. I'm supposed to be feeding this VDC (output of the bridge recitifier after the secondary of the transformer) into an LM117 regulator and...
  17. foTONICS

    multisim convergence assistant

    So I'm trying to build this basic cct to regulate 12VDC, I just wanted to add an ammeter to see how much current I'm drawing but I keep getting this confounded assistant that rarely fixes the problem. I'm pretty sure it's the ammeter that is causing the problem but why, is it just that im using...
  18. foTONICS

    can't remember the name of this chip

    so i can't remember the name of this chip but i know what it does. I believe its a type of op amp or maybe a configuration of one, or just its own chip all together. it's used for noisy signals, only changing states (between high and low) when a threshold is crossed. so say once it goes high...
  19. foTONICS

    multisim questions

    Hey all, so I'm simulating this basic regulator using an LM117 and I have a few questions. 1. I used a voltage divider with a trim pot to the input of the LM117 so I could see the effects of insufficient voltage on the output. This version of multisim I'm using has the feature of resistors...
  20. foTONICS

    CRT anode voltages

    So I was going through the book (PDF) and noticed a typo. It has the anode voltages of A2 and A4 the same, to my knowledge they should be linear in terms of increasing voltages. Does anyone know what I should correct the A2 voltage as? I've attached a screenshot of it. (taken from 'Newnes...
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