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  1. K

    circuit help

    Hi Steven, the two elements you have to suspect are R3 and R1. I would forgo the potentiometer and bias the opamp with two resistors. The resistor to ground and a series resistor that you might be able to forget. The output will be zero volts. As far as R1, it will prevent a changing voltage if...
  2. K

    Radio transmitter

    Get the schematic off the web or out of a book. If you have to plug things in yourself, it will be harder. You can normally guess the transistor by the resistor and the supply voltage.
  3. K

    Car battery..........

    A car battery is switched at the rotor. The rotor turns delivering the path to ground, through the spark plug, for your switched voltage. When you apply 12 volts to the autotransformer the voltage is stepped up. When the rotor loses contact the transformer is grounded out. When the stator lines...
  4. K

    Bridge rectifiers

    I thought you were not going to use a regulator. Normally, battery charges are made to produce not only the voltage but the charging current. This charging current is produced by uping the voltage over the battery voltage. You can make a low current charger by practically not worrying about the...
  5. K

    Low-pass Filter?

    What a good example of a how a transformer works. I normally write the voltage like this : 10 -10 10 0 and this is equal to this 0 0 10 The second example shows the...
  6. K

    wil this work ok?

    I would forget the 10 uf capacitor that is on the output. You have to know that this regulator is looking for a certain amount of current. That current is the operating current of the regulator and the mid current of the transistor. The tranistor current can of course fluctuate by means of the...
  7. K

    MOSFET amp. help

    The major restriction with MOSFET's is the high VGS. This could also prove useful.
  8. K

    Bridge rectifiers

    You can use a larger filter capacitor to bring down the DC just a little bit.But you can add a series inductor and bring it down a little farther. And then you can add a series resistor that will take it the rest of the way. The voltage drop of the resistor will be determined by the current draw...
  9. K

    How two use this transformer for PSU.

    All you need to do is figure out the circuit for it. You can figure the 0 is a center tap and you can check it by using your ohmeter. You can probably assume the voltage is rms. This means you have a 20vrms output with a center tap.
  10. K

    Potential divider

    Now the reason for the voltage dividing. If you imagine that a small tube is the high value resistor and a large tube is the low value resistor you can see that the there requires more energy and thus more voltage across the small tube than the large tube to get the same coulombs per second. The...
  11. K

    Voltage Multiplier

    There is an update to my numbers diagram. I forgot that the negative cycle does indeed show up because the first capacitor is clamped at 10 volts. The fist diode will remain reverse biased and you get the complete cycle which is passed through the capacitors.
  12. K

    Voltage Multiplier

    I don't know what he means by unstable. Maybe the voltage is so high that it shakes the circuit unstable. I don't know. But yes you can use a whopping big capacitor to reduce the ripple and obtain a very fine DC. After all it is just a rectifier and capacitor.
  13. K

    Voltage Multiplier

    The output is not AC. The output is pulsating DC. This is because there is a DC voltage offset becuase of the DC charging point on the sine wave. Here is the voltage relationship. 20 40 10...
  14. K

    need help with timer circuit

    May I recommend the two inverter oscillator. The output of the first inverter goes to the input of the second inverter through a capacitor. The second inverter will have a resistor across it and a diode across it. Connect the cathode to the output. As soon as the input to the second inverter...
  15. K

    need help with timer circuit

    All you need to do is configure the 555 to give you the on time and the off time. This is done by selecting the right external resistors. I'll try and determine what that will be and get back to you. Okay here is the link you want http://www.williamson-labs.com/480_555.htm So now you have a...
  16. K

    encoder output to rs232 conversion

    The operation will involve an encoder, a multiplexar which is selected with a counter that is clocked at the baud rate, and a level translator. You must select no parity and 8 data bits as the format. This is all you need. The input to the multiplexar must have the ready format for rs232 which...
  17. K

    Shift Registers

    I know that you may not get what you want in a shift register. I bought a shift register and the first bit I put into it jumped to the output. Shift registers make good delay devices and are chiefly used for storage. Whenever you have bits of information you must clock the data so that the...
  18. K

    how can do a good lab report ?

    I think it should include the voltage, current, and power. The power dissipated by the devices is important because you can destroy them. The magnitude of the current is important because it gives you an idea about what is acceptable in a system. It's obvious that higher magnitude devices tend...
  19. K

    AC current measurement

    What you will find is that you already have a circuit. The AC is divided across whatever elements you have and the voltage divided by the resistance is the current. In the case of a single element, you don't have a voltage divider. But you still have the voltage and resistance and thus the...
  20. K

    how can i produce 15kV from 15V DC

    Incidentally, I forgot to mention the level translator which will use a switching method to give you the AC which can be rectified to give you a higher DC. So in other words all you need is the capacitor and a switch.
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