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  1. audioguru2

    Micro battery charger

    1) What can you power with only millivolts? 2) Are you going to put a few hundred or a few thousand of your batteries in series to make some useful voltage? 3) What are you going to charge your tiny batteries from, a pulsing circuit powered by another battery? ;D
  2. audioguru2

    L200 Reg plus LM741 Op Amp PSU

    Hi Woody, If your P2 and R4 are correct, it sounds like you have burned away the collector of the L200's internal pass transistor, and its driver transistor can't pass much current. Isn't your L200 bolted tightly to a big heatsink with thermal grease? Isn't your R3 0.1 ohms, not 2.2K? Do you...
  3. audioguru2

    Running LEDs at PWM and current sensor Q.

    Hi, PWM using high current pulses doesn't make an LED appear brighter. If you use 100mA pulses with a 10% duty-cycle it will appear the same as an LED with 10mA DC, unless the pulses are spaced so that the light flickers. PWM is used for dimming, not brightening. Try it. Maybe your LEDs are...
  4. audioguru2

    Wireless USB adapter high gain antena

    Hi Kain, I don't know much about microwave tranceivers but the small round "SW1" on the left side of your card looks like a coaxial connector for an external antenna. My son has a G wireless card in his laptop. Its antenna isn't visible but it has pretty good range. It can steal the bandwidth...
  5. audioguru2

    Another INVERTER we can talk about..

    Hi NVD, Welcome to our forum. The cheap and simple square-wave output inverters use a heavy relay to change-over the power source when the mains power fails. They must detect the failure and move those heavy contacts. Of course the power will be disconnected for some time and your computer might...
  6. audioguru2

    MOSFET for high voltage and high power

    Hi Plouf, I don't know why you want to use a Mosfet in this AC circuit instead of a Triac. A big disadvantage of using a Mosfet is that it will get hot and will need cooling. A Triac switches and won't need much cooling. Your sim shows the Mosfet turned on hard and dissipating 3.38V X 0.48A =...
  7. audioguru2

    0-30 Vdc Stabilized Power Supply

    The two 2N3055 transistors do not go on the pcb. They are bolted to the big heatsink with insulating washers. They are simply in parallel but each has an emitter resistor to the output. There isn't much difference to the pcb. A higher capacity main filter cap, but they are about the same size...
  8. audioguru2

    FM WAVE PROPAGATION

    I dunno. Reversed polarity is all I can think about that would explode caps with such a low voltage. I know! AC voltage at a high current explodes them too! Or DC with a high ripple voltage at high frequency. There is an inverter in our projects section that explodes its coupling capacitors. At...
  9. audioguru2

    TELEVISION

    Even though AC has a much higher peak voltage, DC causes your muscles to contract so you can't let go. AC vibrates your muscles and probablly causes you to be thrown away.
  10. audioguru2

    opamp biasing class A

    Hi Kevin, Don't you think those extremists are ridiculous? They take an opamp with a frequency response from DC to green light and that has an extremely low distortion, and add class-A loading to its output to reduce its distortion! Just for an ordinary headphones amp, and this opamp already has...
  11. audioguru2

    Additional Information

    www.newarkinone.com www.digikey.com
  12. audioguru2

    Temp controlled fan

    It is too simple to make changes. It would be better to design a circuit to do what you want.
  13. audioguru2

    FM WAVE PROPAGATION

    Hi Prateek, Sure, backwards polarity from a high current supply is a good way to blow-up electrolytic capacitors. When I worked on the car-radio production line that's how they tested the anti-reversed-polarity protection diode. They put a heavy bucket over the radio and connected reversed...
  14. audioguru2

    TELEVISION

    It is not as simple as saying it is power that kills: 1) AC or DC makes a big difference. 2) The skin's resistance (wet or dry) or whether the spark has burned into you makes a huge difference. 3) Where on your body the current flows makes a huge difference. You can pass a high current through a...
  15. audioguru2

    Temp controlled fan

    Hi Nibbels, Yeah, that circuit pulses at 100Hz and doesn't have DC available either. It is a very simple circuit to control the speed of the fan with temperature changes, not to turn the fan on and off accurately. Have you tried changing the value of its C1?
  16. audioguru2

    Temp controlled fan

    Hi Nibbels, Welcome to our forum. Which temp-controlled fan project did you make? We have 3 of them. Please "copy shortcut" then paste a link to it. Separate start and stop temps can be adjusted if you use a window comparator circuit. I think the circuits that control the speed of the fan are...
  17. audioguru2

    Electronic Stethoscope 2

    Hi May, I can think of only a few advantages of an electronic stethoscope: 1) Its output can be viewed on an oscilloscope or computer. 2) Its output can be recorded. 3) Its gain can be turned up to hear faint sounds not heard with a mechanical stethoscope. 4) The cutoff frequency of its...
  18. audioguru2

    TELEVISION

    When the high voltage spark burns through your skin and travels much easier inside you, it will probably take only a few uA to kill you. 29mA seems like a lot of current through a person, my country's limit is much lower. Since your skin has a high resistance, the current probably spreads out...
  19. audioguru2

    Night Rider Circuit

    Hi Fkyin, If you search Google www.google.com for Knight Rider Circuit (notice the spelling) you will probably find circuits that use old-fashioned 74LSxxx ICs. I saw one somewhere, maybe on this site. Search here too. The search buttons are at the bottom of this page.
  20. audioguru2

    Coupling capacitors!

    Hi Shahriar, A small cap like a ceramic or tantalum one removes fast voltage changes because its internal resistance and inductance is very low. An electrolytic cap is poor for filtering high frequencies because it is wound like an inductor. You frequently see an electrolytic cap to filter lower...
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