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  1. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    What is the voltage on the collector of q201a (or whatever the first transistor is)? I'm working through the "why no more than 1mA" question.
  2. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    The one you asked immediately prior to me posting it, and then repeated immediately after I posted it.
  3. (*steve*)

    I have created a circuit could anyone plz tell me if this circuit is right!!?

    The 1k resistors and the Vf of this diodes (that I've been very charitable with)
  4. (*steve*)

    Gerber files

    All they want are the files you sent them when you had your original PCB made.
  5. (*steve*)

    I have created a circuit could anyone plz tell me if this circuit is right!!?

    And 200uA through diode clamps will do what?
  6. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    See post number 59. Use ohms law.
  7. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    Assume Vce(sat) is 0V and that the other two transistor's input pin is equivalent to their base resistor to ground. Those conditions lead to a slight overestimate This calculation of current is trivial and I would be profoundly disappointed if you can't do it.
  8. (*steve*)

    Power Dissipation Across A Transistor In Cutoff

    Well you could probably try the online falstad circuit simulator. It's not particularly fast or powerful, but it might do. If the on state voltage is 2.5V, then for an NPN version of these devices, the input terminal (loosely the base) must be 2.5 volts more positive than the emitter. The...
  9. (*steve*)

    AMS1117-3.3 from 5VDC show 0.09vdc

    I'd probably put a 47uF on both the input and the output. Having both a 47uF and a 0.1uF in parallel on both the input and output is best, but I doubt you'd notice the difference.
  10. (*steve*)

    I have created a circuit could anyone plz tell me if this circuit is right!!?

    Unlikely, since it's not even a diode drop above the 0V supply. It is wrong, but not so wrong as to kill anything.
  11. (*steve*)

    Connecting up very small, curved pins.

    Oh, and the pitch is 1.27mm, comparatively huge and almost trivial to hand solder if you know what you're doing.
  12. (*steve*)

    Connecting up very small, curved pins.

    I have some, so I know they were available at some stage. https://www.rockby.com.au/catresultsSql_12.cfm?Stock_no=40628 Just an example. This is a plcc-32 socket, but I have no reason to think that plcc-28 are not similarly available. I just checked and the same place has them listed as out...
  13. (*steve*)

    Connecting up very small, curved pins.

    This package is certainly not impossible to hand solder. A surface mount socket for it may be (but isn't too hard with an oven).
  14. (*steve*)

    Light therapy device

    Look in the resources section for the resource on driving LEDs. It has a section on constant current drivers. You also mentioned constant current "diodes" which are an option not discussed there. Watts are simply Joules per second, so if you want 0.15 Joules and the power of your array is...
  15. (*steve*)

    Making a Wireless Security Camera

    You could, but it would probably cost several times more than buying one with built-in wifi. Also, you'd have a hard time weatherproofing everything to a reasonable standard.
  16. (*steve*)

    AMS1117-3.3 from 5VDC show 0.09vdc

    You could, but it would be some combination of vastly inefficient and not providing the correct voltage. These three terminal regulators are incredibly easy to use, do the job well, and I'm pretty sure you've made a trivial but fundamental mistake. Have you tried what I suggested to allow...
  17. (*steve*)

    LED dimmable lamp

    To run it from the mains I suggest you find an appropriate plugpack. This means you don't need to do any mains wiring. Before you select a plugpack though, you'll need to select a LED and determine how you're going to drive it. The easiest option is probably one of the many dimmable 12V LED...
  18. (*steve*)

    Light therapy device

    If you use a constant current device you don't need to. If you use a resistor and the resistor drops a significant proportion of the voltage you don't need to. These are operating a relatively high currents, so a constant current driver is the better option (well, it always is, but the extra...
  19. (*steve*)

    Setting up idiot led's...

    Probably far too complex, and not protected against spikes, but this will detect current flow with more than about 15mV drop across the sense resistor. With the values as shown, the LED turns on fully with about 150mA being drawn by the bulb. R6 can be reduced for higher current loads. If...
  20. (*steve*)

    AMS1117-3.3 from 5VDC show 0.09vdc

    Well, that's a fixed one. 1117-ADJ (or similar) would be the adjustable one. Well, you should, but I note that you don't have either the input or the output capacitor as specified in the datasheet, and I'm not sure you can reliably push them into a breadboard and expect a good connection...
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