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  1. K

    Negative charge pump

    Hi audioguru. We have circuit building problems. I have transistors and opamps that go out. You know how it is. I really get tired of these problems. But I have some interesting results. I did manage to double the circuit, basically, and get -10volts. The output of the first stage was -3volts...
  2. K

    Negative charge pump

    Okay, here is the tested circuit. It delivers about -8volts. The frequency of the square wave is undetermined.
  3. K

    Negative charge pump

    okay, I fixed the first part of the circuit for the negative charge pump. I was missing a diode in there. Here is the circuit without the resistor values shown. You can play with the resistor values, but I will expand the circuit as I promised and post it.
  4. K

    Negative charge pump

    I have tried everything it seems. I used emitter follower transistors on the opamp outputs. I have put diodes in to get rid of base current when the output goes low. I even put that other transistor as I was wondering if it needs it to put the capacitor at ground. I think when you disconnect the...
  5. K

    Negative charge pump

    Audioguru, I am having trouble transfering the charge to ground. I can only get slightly over -3 volts from the first circuit. What could the problem be? I added a PNP to the first circuit during the charge transfer to help get it at ground potential. If I get it working I'll repost the circuit.
  6. K

    What is Diac?

    http://www.play-hookey.com/semiconductors/diac_triac.html
  7. K

    Voltage regulator + current amplifier?

    A current amplifier won't regulate because there is no feedback. A changing load would cause voltage fluctuation. What you could do is add feedback and that of course leaves you with the original concept. A voltage regulator with an external pass transistor. By the way it is funny how that...
  8. K

    What is Diac?

    I have heard two different stories when it comes to these 5 layer devices. Some would say it's about the current, but I found one that deals with voltage. I like to deal with voltage, as the current is just the requirement which will maintain the voltage. A diac is basically a switch that is...
  9. K

    Negative charge pump

    Here is the new circuit. I hope to build it soon. You might experiment with different resistor values and bigger transistors and larger capacitors for maximum current capabilty. Please disregard the opamp biasing.
  10. K

    Negative charge pump

    Audioguru I have great news. I tested this circuit using 5 volts and it works. I could not hook up the two circuits together because of the lack of breadboard space. However, I tested them independently and found the first circuit to give me -3 volts and the second circuit to give me -9 volts...
  11. K

    AC/DC adaptors: voltage over normal?

    By "unregulated to boot" I meant unregulated "also". By doubling up on regulators I was talking about the situation where you could put two regulators in series to try and get better regulation without setting the current right. A way of compenasating for not having the correct current is to try...
  12. K

    AC/DC adaptors: voltage over normal?

    No I don't think the current rating is maximum. This is the amount of current expected. The thing also has a capacitor I believe to get rid of the ripple. You have an RC circuit when the AC from the transformer drops. The ripple is created from the discharging capacitor and the charging...
  13. K

    Negative charge pump

    Here is something a drew up for those interested in a negative voltage supply made with a charge pump.
  14. K

    The simplest audio amplifier

    Okay. Here is the charge pump that will give us the negative supply.
  15. K

    The simplest audio amplifier

    deleted
  16. K

    measurement

    I can tell you that you should use two ammeters. You want to keep the ratio the same. Bias the collector current at half the rated maximum current. You probably have a kit that supplies a variable postive and a variable negative. Use this configuration. Vary the input voltage until you get the...
  17. K

    + & - DC supply!

    You need a charge pump. This will give you plenty of current if done right too. You can design one with transistors. I'll post the circuit. I am sorry but the output is only -5V and not -10V.
  18. K

    Bass-boost

    You know I wondering if you could run the speaker at just a single polarity. Of course your not getting the full throw. I think one should try the amplifier I posted under Projects titled the simplest car audio amplifier. This will give more power.
  19. K

    Barrier potential discrepancy

    One more equation. Ic = saturation current times e to the Vbe/ Vt where Vt is the thermal voltage. This way you can calculate the current with just a Vbe.
  20. K

    high voltages

    That is very high voltage from a DC source. I would recommend a switch mode like audioguru said. You can make one very simple. The transformer you selct will have an output current rating. This is going to be useless. But the turns ratio will give you a hint at the input current. If you have 1:2...
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