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  1. K

    0-30 Vdc Stabilized Power Supply

    Don't forget the zeners and you have an excellent power supply. The only drawback is the zeners themselves. The voltage will try to change and the regulation of a zener is probably not all as good as a regulator. The fact is the voltage of a zener does change and the change needs to be corrected...
  2. K

    0-20 (3A) and 0-40 (1.5)A Power Supply (Elenco)

    Boy! Isn't that a variable soup. I am confused about the switches. You can select 0-20 or 0-40? That doesn't make sense. But then again I not an expert on commercial power supplies. I don't think I could recognize short circuit protection if I saw it, but the fuse will work.
  3. K

    transformer windings

    I learned something new that I would like to share with everybody. I have a transformer with multiple windings. I thought that the taps off the different windings would return to each other. I found out that the voltage is just stepped down to the winding and that the voltage of the windings has...
  4. K

    Pulse Width Modulation DC Motor Control

    I have seen that there is more than one way to build this oscillator. All the oscillators posted seem to pan out. The one that I have has a capacitor between the two gates and a pullup on the output of the first gate. It does not show the feedback resistor but I know now that it must be there...
  5. K

    Sine wave inverter

    In reference to the design of the inverter under the projects section, couldn't we replace the opamps with transistors? If the device that supplies the sine wave operates at 5v, shouldn't it be a 12v device? Could somebody hint at the design change because I feel that it is not designed entirely...
  6. K

    zener diode don't know value

    Use a 12volt source and a 10kohm resistor. The voltage of the zener will be apparent. Are you sure it's bad? A diode will often display the resistance that surrounds it, thus measuring a low voltage. Zeners will display a voltage under low currents so you don't have to worry about testing it.
  7. K

    help, help, help, it's too hot

    Let's see if we can't come up with a good combination for his thermocoupler. To start, we don't need the inversion. I think he should just ground the input to the opamp and ground one of the wires. You need some phase compensation to keep the opamp on a 20db per decade at higher frequencies. We...
  8. K

    help, help, help, it's too hot

    Wow! You might want to use an opamp after all. Ground the noninverting input and feed one of the wires to ground. The other wire will be fed to the noninverting input that is already biased with a feedback resistor and a resistor from the input to ground.
  9. K

    help, help, help, it's too hot

    You probably don't need an opamp to amplify the 65mv to the ADC. How do you bias the thermocoupler? I feel you must need a voltage across the wire which has a variable resistance. Is this how it works? Just a reminder. Opamps used for common mode rejection reject the common mode noise if it is...
  10. K

    c programing of 2*16 lcd

    It should be easy, but I have found compatibility problems with various software. I am no programmer but I will tell you that the compilers come with aids as you have probably seen. Have you seen the example code that they use? If you can't get it to work then there is a compatibility problem.
  11. K

    voltage controlled oscillators

    I understand what you are saying, but have you proven this? What about the fact that I have applied DC voltages to a VCO and have got unstable output? By the way I have seen the schematic for a VCO and it looks quite complicated.
  12. K

    What Chip Converts Decimal to Pulse ..?

    It is easy to implement this. You just use the standard components. The output will be a train of data with a 1ns pulse width for each bit. When it's done, the next bit will be a repeat of the sequence. A 5 will look like this assuming a 4bit encoder : 0101 0101 0101 0101 until the next number...
  13. K

    voltage controlled oscillators

    I have seen frequency synthesizers that do the very same thing. They incorporate a phase detector, a programmable section, and a crystal. What more is there to it.
  14. K

    What Chip Converts Decimal to Pulse ..?

    1ns is the time of a cycle when talking in terms of frequency. So yes it is a little high but it is 1GHz and not 2GHz. For those used to dealing with pulse width, I am just clarifying this point.
  15. K

    What Chip Converts Decimal to Pulse ..?

    First you need an encoder to give you the binary representation. This goes to a multiplexar. The selects can be cycled with a counter that is clocked at the frequency you want. Let's say the clock time is 1 ns. The counter will increment every 1ns. This means the select will change every 1ns...
  16. K

    voltage controlled oscillators

    Hello Audioguru. You can change the frequency of the VCO because the phase detector is programmed to reduce or increase the frequency produced by the crystal.
  17. K

    how to calculate??

    This isn't at all biased right. What transistor are you using? There isn't any current because you don't have a potential difference between the base and emitter. Keep the emitter positive and use a resistor to ground on the base. I don't see a signal input so I'll assume that this circuit is...
  18. K

    voltage controlled oscillators

    I have seen that VCO's don't operate well with a DC voltage applied to them. I think they have to work in conjunction with a phase detector. It would seem you could design one that works alone but the ones on the market require the phase detector. If you could post your design for one it would...
  19. K

    12v lamp Dimmer lamp ideas?

    What you need is to adjust the amount of AC that is applied to the lamp. You can switch power to the lamp if you want and control the duration of the switch. You just assume that there is always a mains voltage present when in fact it depends on the time. To switch the voltage you need a triac...
  20. K

    single phase controlled rectifier for DC motor

    Then we are talking PWM?
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