Search results

  1. K

    0-30V Stabilized Power Supply

    I guessed at the low impedance load part. The JFEt circuit uses a high current 0VGS instead of a low current 0VGS. If it's similar to a MOSFET, the transconductance is higher. Is a higher transconductance always better? Aside from the fact that there are gain setting resistors which make the VGS...
  2. K

    0-30V Stabilized Power Supply

    Recently I used a JFET in a small circuit. The gm specification recommended is around 0VGS at 15V VDS. I used a very low value source resistor and drain resisitor for gain. Should they be good for low resistance loads?
  3. K

    0-30V Stabilized Power Supply

    The voltages and currents aren't what they should be then. You can make a cheap power supply. This is a 30V stabilized power supply. Either the pot or the transistors used are now of out of specification.
  4. K

    0-30 Vdc Stabilized Power Supply

    oh yeah. how about that.
  5. K

    0-30V Stabilized Power Supply

    WinDTrek, you are on loose ground.
  6. K

    0-30V Stabilized Power Supply

    A polyester capacitor is very cheap.
  7. K

    diodes with breakdown current instead of voltage breakdown

    Current specifications aren't used much for diodes unless they're exceeded. Jfets have the input connected to the channel. The substate is shorted to the source. I'll edit this post. Only MOS field effect transistors have their substrate shorted to the source most often. Jfets are biased with a...
  8. K

    0-30V Stabilized Power Supply

    Jfet input opamps are a great improvement because they are square law devices. Their input voltage needs to be very close to the supply voltage based on Jfet VGS. Maybe 5V less. Does this opamp need a transistor bias voltage so that the bias impedance is higher than would be a resistor.
  9. K

    0-30 Vdc Stabilized Power Supply

    Xristocrat. Tell us what you mean by your earlier posts. What is the design?
  10. K

    0-30 Vdc Stabilized Power Supply

    Xristost, I like the stabilized 30v power supply you work on. So many people want a constant voltage...
  11. K

    ohms law help

    ohm's law. It is the equation from which electronics is derived. I wanted to clamp Q2 but it limits the versatility of the simple variable voltage supply.
  12. K

    0-30V Stabilized Power Supply

    Impedance is slightly different from maxing opamp current. Especially when Q2 handles all the current.
  13. K

    0-30V Stabilized Power Supply

    I modfied this posting.
  14. K

    0-30V Stabilized Power Supply

    I was looking to modify Q2 with a BE diode and a VCE zener and an upstream transistor to drop the voltage for the zener. If Q2 has a low BE operating voltage and the parallel diode doesn't go low impedance, U2 will work fine. It's good to hold Q2 at a constant VCE and VBE. As long as the...
  15. K

    0-30V Stabilized Power Supply

    audio the gain of U2 should only be a liitle more than 2 for low frequency circuits. Only if the powered circuit is very high frequency will C6 lower the feedback enough.
  16. K

    0-30V Stabilized Power Supply

    A higher conduction voltage diode has a high impedance, it only shares it with the transistor. Probably around 15V, the impedance drops and the opamp only follows  the signal. So there is no small signal regulation. But you can always use an opamp to power low power DC circuits. But almost...
  17. K

    0-30V Stabilized Power Supply

    I would want to increase the stability of the supply for small signal regulation. Before and in series with Q2 could be a fully biased NPN transistor so that the bias resistors can set the base voltage. Q2 would only need a BE diode to help limit the voltage drop and a VCE zener diode with a...
  18. K

    0-30V Stabilized Power Supply

    I was thinking of the low current IC's in regard to the high current output. Higher current means a lower beta, a lower impedance and a larger change in current. It wouldn't be an easy circuit to wire up. If any part of the design is wrong or a transistor is damaged or too far out of the design...
  19. K

    0-30V Stabilized Power Supply

    The power supply draws an enormous amont of current. Voltage regulators have line and load reguation. It's a great 30V supply. Haven't built it yet. Naw no way. Tell um.
  20. K

    0-30 Vdc Stabilized Power Supply

    Opamp U1 is a very good circuit! I think it's absolutely great. Tell us what you think about this!
Top