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  1. (*steve*)

    Help on this transformer (make work)

    If it's an autotransformer then it doesn't have a primary and a secondary. Autotransformers have just the one winding.
  2. (*steve*)

    Wanted: Power source

    Well, there are AC power supplies available which allow you to set voltage and frequency. However they're typically extremely expensive. What do you need this for? And when you say 0 to 1000Hz, what is your minimum frequency *really*? I have some equipment capable of detecting some small...
  3. (*steve*)

    LED specification - All about 3mm & 5mm LED's

    Yeah, as I said, I assumed these were white LEDs (i.e. blue + phosphor) in a coloured case. It's just an instance of the colour observed being misleading. As a side note, I also had some blue LEDs of the same type, and I bet these were blue LEDs with phosphor (to give white) and then placed in...
  4. (*steve*)

    BJT transistor saturation

    See here for a discussion of saturation (amongst other things)
  5. (*steve*)

    BJT transistor saturation

    Yes your example indicates saturation, but the transistor would not be in saturation for a significantly higher Ic. Unless your load corresponds to the example given in the datasheet, you need to do some calculations yourself. Out of curiosity, what is the minimum HFE specified for that...
  6. (*steve*)

    BJT transistor saturation

    In addition to the above post by @Ratch, transistors are frequently specified as having a range of HFE. This means that two transistors picked at random and biased with the same base current could vary significantly in their state. For the same load, one might be in saturation, and the other...
  7. (*steve*)

    LED specification - All about 3mm & 5mm LED's

    I have seen the same approx 3.3V Vf on red, green, and yellow LEDs. I'm pretty sure if they were "white" LEDs with a filter. In any case, the colour didn't indicate the Vf.
  8. (*steve*)

    555 pwm controller.

    That's a fairly standard looking bipolar switching regulator. I wouldn't be surprised if you could lash something up using a similar chip.
  9. (*steve*)

    MOSFET Circuit Help

    If the fan is removed from the box and placed some distance from it, but still electrically connected and operating, does the problem persist?
  10. (*steve*)

    PUPS Problems with Uninterruptible Power Supply

    Well... You could have a very small 500W battery, provided you only want 500W for a few seconds. Does the op mean 500Wh?
  11. (*steve*)

    Unable to eliminate ground loop interference (car audio)

    The information you asked for, and received in that previous thread seems fine. However, what you report as a feature in your last post is actually a bug. You say that when there is a signal from the phone it overrides the signal from the radio, but as you've found, this isn't true -- they're...
  12. (*steve*)

    Unable to eliminate ground loop interference (car audio)

    You were perfectly clear. I read the post where you describe your modification. The fact that you hear signal from both sources when the phone is plugged in tells me you haven't wired it up correctly. When you plug the charger in, the radio signal is probably shorted to ground through the...
  13. (*steve*)

    Arduino GPS Transmission

    Well, that project doesn't actually use Google maps from the microcontroller, so it's not a good starting point.
  14. (*steve*)

    Arduino GPS Transmission

    That is both easier and harder :-) I'm sure you can tell Google maps to return a given area, and to overlay something at a particular lat/long. The problem is that you note require internet connectivity, a tcp/ip stack, and the ability to handle the data stream in both directions. I would be...
  15. (*steve*)

    Unable to eliminate ground loop interference (car audio)

    It sounds like your new input doesn't disconnect the existing radio signal when you plug in your phone. I would revise your modification and ensure it is correct. Plugging in the cable at the radio end only should shut off the radio and make the output go quiet (aside from a little nose perhaps).
  16. (*steve*)

    Arduino GPS Transmission

    What do you want to display on the LCD? Is it the relative positions of the two devices? If so, you can do it the "right" way, which involves lots of math that would take forever on an Arduino, or you could take the far simpler approach of getting the difference between the latitude and...
  17. (*steve*)

    What specs are the most important when swapping transistors with another type?

    I can't think of any reason why they may be more likely to oscillate. They appear to be quite similar. I also agree that the SOA graphs are substantially similar. If certainly give than a go.
  18. (*steve*)

    What specs are the most important when swapping transistors with another type?

    I would check that the Vbe is also similar (although I expect it would be). Assuming the amplifier has some sort of adjustment for setting the biasing, you should be able to use a different, albeit similar pair of transistors. Whatever you choose for one, I would check what the manufacturer...
  19. (*steve*)

    SENCORE TF46 CAL

    Pages 29 thru 31 of the manual describe the calibration procedure, including the use of this control. I found the manual on the userequiu.com web site (it was the first hit on Google when I searched for the manual)
  20. (*steve*)

    SENCORE TF46 CAL

    Under some operating condition the meter should show fsd. This allows the meter reading to be set to fsd when those conditions are met (possibly during calibration). Playing around with it may make the device less accurate. (Ok, in retrospect, you may be fully aware of that :-))
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