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  1. audioguru2

    Simple help with transistors!!

    Your new circuit will work fine. The LED in the switch will light whenever the fog lights are on unless you connect R1 to the relay side of the switch. Then it will light only when the relay is active. I don't know which relay you will use but its coil's current is probably pretty low.
  2. audioguru2

    350w Studio Anfi Full Proje

    I don't want to pay Silicon Chip magazine to read their article. Instead, I found a kit of the amp and it produces 200W into 8 ohms or 350W into 4 ohms. One of the kits supplied subtitute transistors that had a different pin-out and wouldn't fit on the pcb.
  3. audioguru2

    350w Studio Anfi Full Proje

    Hello Gevv, Please tell us something about your amplifier. Does it have low distortion? Is it wideband?
  4. audioguru2

    Bridge problem!

    Good! You fixed it. Nice going. ;D
  5. audioguru2

    LM317 Variable power supply

    18VDC is too low to charge an "18V" lead-acid battery. The battery needs at least 21.6V to fully charge. What spec is that? Charging current? No. The supply voltage is too low to charge the battery. You calculate the time only if you know the current drain of the laptop. Just make sure that the...
  6. audioguru2

    LM317 Variable power supply

    Your revised circuit is much better. 1k is so high that the batteries will get hardly any charging current. The resistor's value is calculated from the input voltage when loaded, the battery's recommended charging current and time. We can assume that the lead-acid batteries each have an average...
  7. audioguru2

    plz help me out !!

    74LS is much slower than 74AS. 74HC is also much slower.
  8. audioguru2

    car battery tester

    The schematic calls the circuit "a level monitor". ;D Hee, hee. Maybe it shows how straight and level is the battery. Maybe it also shows if the battery is nearly dry. Hee, hee. ;D
  9. audioguru2

    LM317 Variable power supply

    Your batteries are shown wired in parallel, not in series. There is not a current-limiting resistor from the power input to the batteries. Therefore they will charge with an extremely high current. The diodes to the output are backwards and are not needed anyway.
  10. audioguru2

    FM impedance antenna matching

    I haven't seen a T0-39 case on a transistor for many years. It might melt with 13.8V. Digikey don't sell 2N3866 transistors so either it isn't made anymore or nobody is buying it. The audio preamp transistor in my transmitter is biased for a 5V supply.
  11. audioguru2

    Plz help me in understanding this RF reciever

    What 433MHz receiver? You posted the schematic of a very simple regenerative receiver that has only a single transistor. It doesn't use PLL and doesn't have a crystal. Better circuits are used in cheap remote controlled toys.
  12. audioguru2

    how to design very small 6V power supply @100mA

    I bought my surplus 5V/2A tiny name-brand switching power supplies at a very good price. Their label says that the voltage is adjustable over a wide range but they are sealed so I will cut one open to try it. I don't know where to buy a high frequency core for the transformer, then it would be...
  13. audioguru2

    shake light

    Hi Ante, What will turn the stepper motor? Windmill? Hand crank with gears?
  14. audioguru2

    Bridge problem!

    The board you show is poor for a high current amplifier. Years ago I made a similar amplifier with Veroboard and it worked well. Maybe my wiring layout was lucky. Tantalum capacitors have poor reliability and cause audio distortion when used as coupling capacitors. Electrolytic capacitors are...
  15. audioguru2

    how to design very small 6V power supply @100mA

    A transformer provides isolation for safety. A switching power supply can operate at a high frequency so the transformer's size can be very small. I bought some 5V/2A switching power supplies as surplus (2 years old, name brand) for a very low price. They are very small and are a very low...
  16. audioguru2

    Bridge problem!

    Maybe that is your problem. This IC has a very high output current that can cause positive feedback in the wiring. Good.
  17. audioguru2

    shake light

    I know what! Shake it really fast, like at about 100Hz then it would make enough current to charge a capacitor or a battery. ;D
  18. audioguru2

    help for inverter

    A simple inverter is an oscillator driving two push-pull power transistors that switch a battery's current into a stepup transformer. An inverter isn't perfect so wastes some power by getting warm. About 120W must come from a battery to get 100W output from the inverter. The battery must be...
  19. audioguru2

    shake light

    On TV the "shake light" is a cartoon, it is not real.
  20. audioguru2

    Bridge problem!

    The only difference on the datasheet is the matching of the pin 8 and pin 10 voltages for the TDA2005M for a bridged IC. Your TDA2005S doesn't have the voltages matched causing  them to be 1.6V different. Maybe the 1.6V difference is causing the IC to heat then shut-down for a moment before...
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