Search results

Search Forums New Posts
  1. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    No, it's in common emitter config. It's pretty much impossible for these biased transistors to be anything else. T201 will start turning on when TM+ exceeds Vdd5 by more than about 1.8V.
  2. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    Oh, and where did you get the idea that any of those transistors was operating in common base mode?
  3. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    None of the transistors will be turned on. The will be some dissipation due to the the approx 0.4V across the bias resistors in T201. All of the other transistorthan are off, so assuming the voltages you mention are stiff and the loads on the output are high impedance, 10E will be Vdd5, and 11...
  4. (*steve*)

    Connection knowledge

    Did it work with the transistor around the right way? I'm not sure if you're saying that it only works backwards, it that it works both ways. There are several ways you could have made this mistake. I don't know, for example if you took the signal from the collector or emitter before you...
  5. (*steve*)

    Correct name for push button switch

    Switches with one normally open set of contacted and one normally closed set of contacted are common in E-stop buttons (although these normally latch) I'm sure I've seen non latching switches of this nature... Here is a page of them from Digikey. They're described as "DPST (1 NO, 1 NC)"
  6. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    Ic is zero (or very close to zero) so Pd is zero (or very close to zero). So Vce must be the village across the to notes when no current flows between them. Is this homework? Show us the question in full.
  7. (*steve*)

    Resistance and Inductance

    The only Polish calculators I can conceive of come from Poland. RPN is never called "Polish" (to my knowledge) and it's connection with Poland is via the nationality of the author of what has become known as Polish notation (a form of notation developed for symbolic logic, and only as an...
  8. (*steve*)

    Connection knowledge

    There still just a part of it. But it's clear that your transistorthan has the collector and emitter back to front. If it works, this diagram is likely incorrect. It looks like something you drew from the breadboard, not the schematic you started off with.
  9. (*steve*)

    Connection knowledge

    Do you have the schematic for the whole circuit rather than a photo of just a part of it?
  10. (*steve*)

    Hello All

    I remember thinking how great the 8 inch one were.
  11. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    Do you want Vce or dissipation? By definition dissipation will be at or very close to zero and Vce will be at or very near maximum.
  12. (*steve*)

    Controlling a simple DC brushed motor by PWM

    You might be able to find a controller for an old ebike or escooter. 24V 300W brushed motors we're not uncommon prior to the use of brushless DC motors.
  13. (*steve*)

    Question about a bluetooth headphone battery.

    Leaving it out in the rain? Nobody knew electronics weren't meant to get wet! Get onto eBay and find a lipo battery rated at 3.7V and 180mAh. If it looks to be roughly the same shape and size as yours, buy it. If you're lucky you haven't drowned anything else. Leave the headset indoors...
  14. (*steve*)

    ID Obsolete Motorola Communications Capacitors?

    A photo with something for scale might help. The capacitance you can get by measuring them. The voltage you could estimate based on the approximate date on manufacture, the side, and the capacitance. It's possible that after measuring the capacitance of a few, some part of the part number...
  15. (*steve*)

    Wheatstone Bridge (thermistor) to Op Amp

    The values must be such that the ratios of the two resistors must be very close. Without feedback, the variable resistance must cause the potential of one input to be able to be adjusted above and below the other. So for the arms to be balanced, if one side is 10k and 15k, the other side must...
  16. (*steve*)

    Wheatstone Bridge (thermistor) to Op Amp

    That circuit will cause the output to be either as positive or as negative as it can be. As negative as it can be, for the 741, is not the negative supply rail. It's hard to read the resistor values, but I suggest they are such that the voltage on the non inverting (+) input is always lot than...
  17. (*steve*)

    Trying to repair our VFD

    That sounds like an internal part number. These are used to obscure the part that is being used and/or to integrate with an internal parts system. You can look for a cross reference. Companies like HP would occasionally include relevant information in their service manuals, for others they...
  18. (*steve*)

    Resistance and Inductance

    Yes, for any equation you have to mentally perform the infix to postfix notation conversion. And where the calculator can do this quickly, the algebraic I notation calculator will have the lead. Any calculator using algebraic notation must do the conversion to RPN (or similar) in code (even...
  19. (*steve*)

    Trying to repair our VFD

    The chunks I saw appear to be marks on a conformal coating. Your first task now is to identify what is written on that chip. From this view we can't see anything. Maybe you can if the lighting is coming from another angle. Maybe the markings have been removed :-(
  20. (*steve*)

    Trying to repair our VFD

    It seems to have chunks missing
Top