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  1. L

    Solar Race Car - Please Help

    Look for a low-voltage low-current motor as used in battery powered equipment. I had just torn apart an old digital camera and removed the motor. It is 0.44" in diameter and 0.6" long. Hooked it up and at 1.3 V it drew 40 mA and felt like it had sufficient torque to power a small toy car...
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    OpAmp circuit

    The common method for making an analog divider is to obtain a multiplier IC from a place such as Analog Devices and use it in the feedback loop of an op amp . See MT-079: Analog Multipliers, http://www.analog.com/static/imported-files/tutorials/MT-079.pdf for an introduction. But there are...
  3. L

    calculating currents using KCL and KVL

    Indeed, i.a is the current at the lower left corner (flowing to the right) while i.b is the current at the upper right corner (flowing to the left). The first step is to use i.a and i.b to calculate voltage drops, then use KVL around the outer loop to get the voltage across the 16+4 resistor...
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    how to calculate voltage drop at R1 , R2 ,R3??

    Great, now I can add source transformation to the list of gimmicks lost in my fuzzy memory.
  5. L

    calculating currents using KCL and KVL

    To write the node equations for this circuit I added a reference ground to the minus terminal of the power supply and combined all series resistors, then put labels the three nodes as shown. Solving the node equations for the given constraint conditions leads to an inconsistency for the value...
  6. L

    how to calculate voltage drop at R1 , R2 ,R3??

    One of the hard facts of life is that I was taught many such principles for the purpose of reducing the work necessary to solve circuit problems back when the only calculation aid was a slide rule - and I have forgotten them. But node equations I can remember. And I can attest that I have...
  7. L

    how to calculate voltage drop at R1 , R2 ,R3??

    The straightforward method is to write the node equation(s) for the circuit and solve that. Here there is only one node (at the junction of the 3 resistors) so there is only one equation for the node voltage. Superposition is a gimmick that can reduce the amount of work involved but only if...
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    Transistor

    So did you write down what you know about the currents flowing in this circuit? How do the currents relate to the node voltages? What value of gain will you use for T1? How many unknown variables are there? How many independent equations will you need for a solution?
  9. L

    Transistor

    Start by writing down what you know about the circuit. A standard assumption is for the voltage at the base of T1. Then the current flowing into the base comes through R2 and R3. I3=(Vcc-Vb)/R3. I2=(Vce-Vb)/R2. So Ib=I2+I3 and with the transistor gain, B, Ic=B(Ib). And finally...
  10. L

    Help with voltage doubler

    Think of the diode as a switch. For half of the power cycle it is closed, for the other half it is open. When Vin is negative the diode is forward biased (closed), no current flows through the load (shorted by the closed switch), and the capacitor becomes fully charged (minus left, positive...
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    MOSFET Driver?

    Texas Instruments has a good application note on MOSFET driver circuits. http://www.ti.com/lit/ml/slup169/slup169.pdf
  12. L

    Backup Internet Access through Secondary Router

    What is the voltage across C2 when the battery is charging? What kind of battery is it? Does the battery require special circuitry to keep from being overcharged?
  13. L

    Please Hep with autobalancing motor project

    I would suggest two 12V SPDT relays. One relay would be activated by the blue line, the other by the yellow line. The first relay pole would be connected to the '+' motor terminal while the second relay pole would be connected to the '-' motor terminal. The inactive relay throw switches to...
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    manipulate voltage output in transimpedance amp circuit

    C128 in combination with the output resistor forms a low-pass filter by shunting higher frequency signals to ground. According to Thevenin's Theorem, placing a resistor across C128 will decrease the equivalent resistance driving the capacitor thereby raising the corner frequency of the low-pass...
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    Can u pls explain a threshold volt for a ujt

    UJT threshold voltage is the peak emitter voltage (with respect to B1) Vp at which point the operating curve enters its negative resistance region, leading to a sharp rise in the emitter current and a lowering of the emitter voltage to that of one forward biased PN junction, Vf. The UJT...
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    help? suggested resources, materials, relevant tutoring?

    Are you an art student at a university? Does the university have an engineering department? Perhaps you can switch your major from art to electronics engineering. My impression from your statement of goals is that you need an EE degree so you can function as an engineer who also has an art...
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    manipulate voltage output in transimpedance amp circuit

    In this transimpedance configuration the output voltage is controlled by the current flowing into pin J25-3 from R78. With no current the output voltage should be zero. All the current that flows into J25-3 comes through R78, and that V=IR voltage drop across the resistor becomes the output...
  18. L

    plasma speaker

    How hot did the heatsink get just before 'the MOSFET blew'? How large was the heatsink? Did you mount the IRF540 with thermal conducting paste?
  19. L

    Control systems

    See attached example for a series RLC circuit. Write the s-domain node equation(s) and solve to obtain Vo/Vin which is the transfer function T(s). Set the real part of 's' to zero for the Bode magnitude plot.
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    Simple amplifire

    Stoking the desired performance from an amplifire requires careful attention to power dissipation levels following ignition by the power supply. Select a small-signal transistor with a high current rating in a plastic TO-92 package. Keep the collector current well below the maximum rating to...
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