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  1. audioguru2

    0-18V Pos/Neg 1A Current Limited

    C11 and C12 slow down the outputs too much, causing poor voltage regulation if the load current changes of if the load current is modulated. The circuit will have serious overshoots and might oscillate.
  2. audioguru2

    Calculate value of base-emitter resistor for Dark Activated Light

    You forgot that the base of the NPN transistor cannot go higher than about 0.65V so in the light the base has some current. The 7k resistor has a current of (6V - 0.65V)/7k= 764uA. The 4k LDR has a current of 0.65V/4k= 163uA. Then the base current is 764uA - 163uA= 601uA so it is turned on a...
  3. audioguru2

    Calculate value of base-emitter resistor for Dark Activated Light

    The datasheet for the BC548 shows that it saturates properly when its base current is 1/20th its collector current. When the transistor is saturated its collector current is 15mA then its base current should be 15mA/20= 750uA. Then R1 will be 5.3V/750uA= about 7k. In room light the base voltage...
  4. audioguru2

    ANTI-AGING

    Your frequencies are completely wrong and what you say is also completely wrong. Microwaves do not end at 75mHz which is a VERY low frequency. Microwaves are from about 3GHz to about 300GHz. FM radio is around 100MHz which is VHF. UHF is from 300MHz to about 300GHz, IR is from 300GHz to about...
  5. audioguru2

    0-30 VDC Stabilized Power Supply 0.002-3 A

    When a capacitor is discharged by a high load current then its voltage begins to drop immediately since it has no voltage regulation. When you want the output capacitor discharged then you are using a transistor that will vaporize. The only thing limiting the current in the discharge transistor...
  6. audioguru2

    Current monitor/sensor

    If there is a positive input voltage to the opamp (+) input, the current flows from the emitter of the BD139 through the base-emitter diodes of the output transistors and through the low value resistors to ground. The 1k emitter to ground resistor of the BD139 also has current in it. When there...
  7. audioguru2

    0-30V Stabilized Power Supply

    The opamps will be cooler if they are TLE2141 singles.
  8. audioguru2

    0-30 VDC Stabilized Power Supply 0.002-3 A

    You do not need a huge output capacitor because the circuit has voltage regulation. Actually this original old circuit from a Greek kit has many overloaded parts and is not reliable. We fixed in and you can see the improved circuit in the forum. A Chinese kit copy (from Banggood or something)...
  9. audioguru2

    ANTI-AGING

    It is not smart to zap and burn a person with high power RF energy. It is not a medical device and will not cure anything, It might cause cancer. It is absolutely normal for an old person to age. Let it happen. I recently turned 70 years old but I take good care of myself so I am very healthy...
  10. audioguru2

    diodes

    Kevin, we cannot hear you.
  11. audioguru2

    Power conversion

    I do not know which planet you live on but here in Canada the ringing is a 90VAC/20Hz signal on the telephone line. The 52VDC is still there during ringing and when a phone goes off hook it draws current from the 52VDC which is sensed and stops the ringing and connects the audio from two phones.
  12. audioguru2

    Current monitor/sensor

    When the battery voltage is low or when the battery is not connected to the collectors of the output transistors then when the BD139 turns on its load is the base-emitter diodes of the output transistor in series with the very low value resistors causing a very high current in the BD139. I said...
  13. audioguru2

    Current monitor/sensor

    I see why the BD139 draws a high current in your battery discharger circuit: There should be a current-limiting resistor between the emitter of the BD139 and the bases of the output transistors.
  14. audioguru2

    Current monitor/sensor

    Opamp U2, the BD139 emitter-follower and the output transistors emitter-followers make a DC amplifier with a voltage gain of about 3.07 times. If the input to U2 is 0V then the output of U2 is about +1V and the output of the project is 0V. If the input to U2 is +5V then its output is about +6.5V...
  15. audioguru2

    Power conversion

    The current in a telephone line is no where near 1A, if you are close to the exchange it is about 50mA and if you are far it is maybe 10mA. The power that feeds a telephone has a 300 ohm resistor (a relay coil) on each of the two wires so the phone transmits into 600 ohms and receives from 600...
  16. audioguru2

    Current monitor/sensor

    Like I said, maybe an output transistor is shorted (or wired wrong) making the output voltage of the power supply as high as it can go. Since you removed the BD139 transistor then the diode D10 on the original schematic connected to it and to the project's output conducts and forces the output...
  17. audioguru2

    Current monitor/sensor

    The opamp , BD139 or an output transistor is shorted.
  18. audioguru2

    diodes

    Kevin, you do not make any sense.
  19. audioguru2

    Current monitor/sensor

    If you have 0V on the (+) input pin of the LM324 opamp and its (-) input is at a positive voltage of about 0.6V then its output should be as low as it can go which is about 0.01V so thall the transistors should be turned off. If the voltage at the 0.5 ohm resistor is 0.6V then the bases of the...
  20. audioguru2

    diodes

    There is no voltage multiplier in this thread.
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