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  1. ramussons

    No reset button found in 4G LTE Mobile WiFi Modem

    This is totally software controlled. Plug in the device to a pc usb port. The pc will initially indicate a small capacity ROM that has an executable file. Running that will install the drivers and open a window to configure the device. The setting button has a Factory Reset option to reset the...
  2. ramussons

    2.4v NICAD CHARGER?

    There is a flaw in your schematic. How is the lower BC547 supposed to function?
  3. ramussons

    Filters Common Mode Ckoke

    The thickness of the wires indicate a EMI power filter of sorts....
  4. ramussons

    240 single to 380 3ph

    Even if we decipher your English, it makes no sense since we have no idea of what Capacitors, Breaker, .... you are referring to. What is this convertor? Any Name, Model number... ? Can you upload some decent photographs of this unit? The PCB both sides. Can you trace the wiring ? The we...
  5. ramussons

    Sony PS-F9 turntable. Disconnected component don't know where it goes?

    The RF choke is to stop the FM signal flowing into the power lines. If this is not done, the neighbours too can listen in on their radio since the FM signal is on the normal FM band. Some others may complain about "interference" to their FM reception.
  6. ramussons

    Sony PS-F9 turntable. Disconnected component don't know where it goes?

    That is a RF choke, and in all probability, in the FM transmitter power feed. It may not be on the PCB, but mounted around the AC input socket on a auxiliary switch terminal.
  7. ramussons

    Guitar Level To RCA Line Level Preamp

    In any case, that virtual ground formed by those 2 resistors of 10 K will need a Capacitor to ground. Have a look at the modified circuit.
  8. ramussons

    Guitar Level To RCA Line Level Preamp

    That buffering serves no purpose. That .47 uF capacitor blocks the DC anyway. Unless the circuit is modified relocating that capacitor as shown below. Not sure what purpose it serves. You need only that 1458.
  9. ramussons

    want to tinker with my UPS.....

    If you replace the 12 V battery with a higher mAh one, you will not damage the charging circuitry. It will take longer to charge the battery. And your PC will run longer.
  10. ramussons

    Is it necessary to power on in order to diagnose failure IC of CRT TV?

    You will be taking a lot of risks, mainly because you are new to this. CRT's handle about 10 Kilo Volts on its screen!. The capacitors can retain charge for quite some time - maybe days. And you cannot troubleshoot without switching ON.
  11. ramussons

    Rice cooker tripping breaker when switched on (Zojirushi NP-HCC10)

    Read Post #5 again. The best possibility is a shorted IGBT. Make sure that the cooling part is dust free before replacement. A higher current rated IGBT is better. The bad possibility is a failed Gate drive - it is a long chain and tracking down the faulty component is not simple. You will...
  12. ramussons

    Rice cooker tripping breaker when switched on (Zojirushi NP-HCC10)

    There is a Switching Transistor (MosFet/IGBT) (mounted on a massive heat sink) that feeds the Induction Coil. That is a short. Maybe due to overheating. Check all components in its driver chain. Use an incandescent bulb Indicator in series with the supply as advised in Post #4 to prevent...
  13. ramussons

    Calculate the transfer function of an OPAMP circuit

    What is the output from the Hall sensor? If the Quiescent output of the sensor is not Exactly 2.5 Volts (R1=R2), the output will linearly change to 0 or 5 volts, or Sensor Quiescent * (R4/R5), whichever is lower.
  14. ramussons

    how many watt resistor do i need for 2 volts 1 ohm

    P=E^2/R = 4W
  15. ramussons

    Power Amp Repair Help - Fuses keeps blowing

    One standard procedure I follow in troubleshooting electronic equipment is to put a 60 Watt Incandescent bulb in series with the main power supply. It acts as a current limiter to prevent further damage. It also acts as a sort of visual indicator of currents drawn. You will save on fuses...
  16. ramussons

    What incandescent lamp wattage to buy for PSU troubleshooting ?

    One person talks about the lamp in Series with the Mains Input, another about using the lamp as a Dummy Load.:oops: A 60 Watt Filament Bulb at the mains input acts as a Current Limiter ( with a visual indication of the current drawn) so that there is no damage to any component in case of a...
  17. ramussons

    Cable voltage drop - capacitor reservoir

    Wikipedia only mentions about the making of a super capacitor. It does not say that it is not a Electrolytic capacitor.
  18. ramussons

    DC voltage reduction circuit needed

    Just make sure that the Shunt Transistor has an forced aircooled heat sink.
  19. ramussons

    DC 12 V to AC 220 V

    The frequency will change depending on the load. The Inductance of the coils will change depending on the load currents.
  20. ramussons

    What incandescent lamp wattage to buy for PSU troubleshooting ?

    If you are not doing a Load Test, 60 Watts is fine. I use this while troubleshooting a wide variety of equipment. This morning it was a uWave oven (the control board). I suggest you order 100 Watt bulbs, use them in series / parallel depending on requirement.
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