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  1. BobK

    IR Sensor

    Hi, and welcome to the forum. What kind of detector are you using? This might be a simple photodiode or phototransistor or it might be a complete detector + demodulator designed to operate at a specific frequency. The transmitter and receiver circuits are different depending on which type...
  2. BobK

    Single, half, full-bridge PWM...

    Half bridge and full bridge PWM on a PIC ECCP are means of driving a half-bridge or full H-bridge, typically for motor control. These allow either 2 or 4 outputs to control each of the switches in your half (2) or full (4) bridge. It also allows you to insert dead-time between the switching of...
  3. BobK

    Controlling High Currents with Microcontroller

    At that point, you might as well throw in an inductor and have a switching power supply. In fact, that is probably the best solution. Bob
  4. BobK

    opamp

    Not nearly enough information. What is the PNP transistor doing? What is the opamp doing? What kind of sensor? What is the output controlling? Since you seem to know so little about it, what makes you think the solution involves a PNP transistor and an opamp? Bob
  5. BobK

    Controlling High Currents with Microcontroller

    All of you may be convinced, but I am not. The OP has not stated what the load is. For some loads, PWM is appropriate, for others it could be disastrous. Bob
  6. BobK

    Project 1 : Battery pack / charger

    You should not be charging LIPO batteries without at least a voltage limited (4.2V) constant current power supply. This type of battery is very intolerant of overcharging and can catch fire or even explode, and both current and voltage must be limited to prevent that. Bob
  7. BobK

    solar phone charger

    People keep coming here trying to make solar chargers from small solar panels. If you work out the details, you actually need about 1 sq ft of panel to make a charger that will charge a phone at the normal rate. Bob
  8. BobK

    Capacitors in parallel effects on frequency

    Do you understand voltage dividers in DC circuits? You will not understand RC filters until you do. Bob
  9. BobK

    What would 'high-power' be considered? (Constant Current Source)

    There certainly is not a threshold that determines whether this is a high power circuit or low power, the designs need to change a bit for each step in power. For your case, since the supply voltage is close to that of the forward voltage, I would tend toward using a simple constant current...
  10. BobK

    Low voltage Relays

    No, your base voltage will be in the range of 0.6 to 1V, otherwise the transistor will be destroyed. That is why you need a resistor. The resistor will drop the difference between the typically 0.7V on the base and the 2V coming in. I presume there is a formula in resource I linked to, but I...
  11. BobK

    AC power generation and transformers

    The side that is connected to ground is neutral the side that is not is hot. It is arbitrary and indeed must be because there is not difference between the two. If you touch the neutral wire only, you would not get a shock. If you touch the hot wire only it depends on many other factors. If...
  12. BobK

    pwm controller chip

    The rise time and fall time will depend on the gate capacitance of the IGBT and the current capability of the gate driver. Are you using a gate driver chip? If not, you probably should be. Bob
  13. BobK

    Controlling High Currents with Microcontroller

    Since they would be generated by a micro, the pulse can certainly go from 0 to 100%. Bob
  14. BobK

    connect optical audio speakers to tv with no optical audio

    Are the TV and the Bose plugged into the same outlet? If not, try that. Bob
  15. BobK

    Relationship between Frequency, Inductance and Resistance

    Nice little circuit. I LTSPICEd it with 2n3904's. For a 10u inductor I get 10.75uH from the formula. For a 100u inductor I get 101.5 For a 1u inductor I get 1.55uH So it looks like it works pretty good down to 10u and is off by 50% at 1u. With RF transistors it would presumably do better at...
  16. BobK

    My Project motor driver Smoked what driver i really need ?

    It is very simple. You need a motor controller that can handle the stall current. Bob
  17. BobK

    Help with voltage follower

    500mA sounds really high for a dimming signal, even if you had 100 of them. Can you post a link to the LED driver specs? Bob
  18. BobK

    Project 1 : Battery pack / charger

    To charge a LIPO at 700mA you will need 4.2V * 0.7A = 2.94W. You cannot get this from a 1.5W solar panel. In fact, you cant get it from a 3W solar panel except under ideal conditions. You need probably 3X the size of solar panel that you have. A buck-boost converter does not help. They can...
  19. BobK

    Problem with 5v power supply

    The one you showed in post #6 was more like it. What happened to that one? Bob
  20. BobK

    Two functions in the high priority interrupt.

    Do not manipulate GIE in your interrupt routine. This is done automatically by the hardware. When you set GIE within the interrupt routine, you have allowed another interrupt to occur before you have returned from the first handler, causing perhaps a stack overflow if the interrupts are coming...
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