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  1. Alec_t

    Op amp LM339 help

    What is the impedance of the mystery source of the signal feeding pin 7?
  2. Alec_t

    Op amp LM339 help

    Are you sure there isn't an inadvertent short between pins 1 and 6 of the '339?
  3. Alec_t

    Induction heater control --- simulation problem

    I think more elaborate smoothing would be called for to suppress mains-borne noise. Won't such noise play havoc with a phase-sensitive control loop such as you are planning?
  4. Alec_t

    Unable to read frequency of a tone signal with a frequency meter.

    Glad someone agrees :)
  5. Alec_t

    Problems with iPhone 5V car power supply

    Have you checked the cut-off plug to see if the white and green wires in it have any measurable resistance to the black and red?
  6. Alec_t

    Induction heater control --- simulation problem

    Are you not smoothing the rectified mains? You would never be able to keep up with all the changes due to spikes and other short-term variations caused by interference and load dumps.
  7. Alec_t

    I need to maintain a half-full 55-gallon drum at 180°F?

    +1 on the external hot-plate.
  8. Alec_t

    MOSFET pull down in linear region

    Vgs = 30V would kill most fets! Unless the 3.3V drops extremely slowly the linear state would be brief. With such high resistor values there will be only miniscule power dissipated in either fet.
  9. Alec_t

    I need to maintain a half-full 55-gallon drum at 180°F?

    Get an element which is food-safe (stainless-steel sheathed?) and has an easy-clean shape.
  10. Alec_t

    Hello can somebody tell me please collector capacitor

    Eh?
  11. Alec_t

    Hello can somebody tell me please collector capacitor

    Is this article wrong then, Ratch? Q=CV, so for a given C the charge and voltage are proportional. Energy E = CV^2/2.
  12. Alec_t

    Current sensing circuit help

    You won't get good measurements of current which has such a large change in value unless you have a current meter with a range-changing feature, e.g the ability to switch in different burden resistors across the CT secondary, or switch in different CT turns ratios.
  13. Alec_t

    Hello can somebody tell me please collector capacitor

    It stores charge. What are you trying to do with that circuit?
  14. Alec_t

    I need to maintain a half-full 55-gallon drum at 180°F?

    If uniformity of temperature is important you will need a stirrer of some sort. Good thermal insulation around the drum will help with the uniformity issue and to minimise power consumption. What will fill the drum?
  15. Alec_t

    Unable to read frequency of a tone signal with a frequency meter.

    The write-up for the frequency counter says: "Channel A (0.01Hz to 50 MHz) Frequency range : DC couple 0.01Hz to 100 Hz, AC couple 100Hz to 50 MHz Sensitivity : "DC" 0.01 Hz - 1 Hz ≤ 500m Vp-p , 1 Hz - 100Hz ≤ 80m Vrms "AC" 100 Hz - 50 M Hz ≤ 80m Vrms " Should that be interpreted as...
  16. Alec_t

    Unable to read frequency of a tone signal with a frequency meter.

    :confused: You said you were using Channel 3.
  17. Alec_t

    LTC1050 to NJM2904D circuit

    My bad. Here are some CMOS op-amps. If Audioguru has a particular favourite perhaps he'd post details?
  18. Alec_t

    LTC1050 to NJM2904D circuit

    Plenty to choose from. Here are examples of JFET input op-amps.
  19. Alec_t

    Unable to read frequency of a tone signal with a frequency meter.

    Is that a 50Ω input? If so, it would overload the circuit under test.
  20. Alec_t

    Unable to read frequency of a tone signal with a frequency meter.

    Are you using your meter on Channel A with a x1 attenuator setting?
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