Loading ...
Sorry, an error occurred while loading the content.

Re: 6V lamp and led's solved by lowering to 3 AA

Expand Messages
  • Steve
    To answer your question about heat in resistors vs transistors, if the transistor is being used as just an adjustable resistance, heat loss/efficiency is
    Message 1 of 5 , Sep 1 12:02 AM
    • 0 Attachment
      To answer your question about heat in resistors vs transistors, if the
      transistor is being used as just an adjustable resistance, heat
      loss/efficiency is exactly the same.

      So 1.5V dropped at 25mA is 37.5mW wasted power whether it is dropped
      in a resistor or a transistor.

      The way to get less power loss is to use a switching regulator. But I
      suspect it will be beyond your current skills, something for a future
      project.

      Steve Greenfield

      --- In Electronics_101@yahoogroups.com, terramir <terramir@...> wrote:
      >
      > well I actually solved my own resistor heat problem, I soldered the
      resistors between the + & - side of one of the battery spaces lowering
      the start voltage to 4.5V which is much closer to the 3.2-3.2 forward
      voltage. hence wasting less energy on heat production simple solution
      to a problem I coul;d have made much more complex.
      > Problem solved ty for your guys input though, I might use those
      solutions later for other lights, cause the seem a bit more elegant
      and even more power saving in the end.
      > terramir
      >
    • terramir
      used a switching regulator before (although copied direct off a web circuit) and also the lm317T (which is one in a little package but that one ain t that
      Message 2 of 5 , Sep 1 12:44 AM
      • 0 Attachment
        used a switching regulator before (although copied direct off a web circuit) and also the lm317T (which is one in a little package but that one ain't that effcient) catch is most ready designed switching regulators have the little catch of being sort of big monsters, at least in regards to putting them in a real small enclosure. not much room in that sort of lamp. Actually I liked the other idea a bit better using a boost chip, but then again the big problem is fitting the toridal core in one of those casings not to mention cooling the switching transistor.
        space was of the essence here, and well using 4x 68 ohm 1/4W in parallel with 4x68 1/4W in series with a 100ohm pot used as a variable resistor  was the best I could do with the space provided by the dollar store bike light and the parts I had handy at ATM.  
        Making "prebaked" circuits work has never been my problem I want to really learn a bit more so I can design some things that are a little outside the box. I have little money most of the time so I tend to think on how I can do something without spending alot of money.
        off to see that navy manul some more :P
        terramir
         
        --- On Mon, 9/1/08, Steve <alienrelics@...> wrote:

        From: Steve <alienrelics@...>
        Subject: [Electronics_101] Re: 6V lamp and led's solved by lowering to 3 AA
        To: Electronics_101@yahoogroups.com
        Date: Monday, September 1, 2008, 12:02 AM






        To answer your question about heat in resistors vs transistors, if the
        transistor is being used as just an adjustable resistance, heat
        loss/efficiency is exactly the same.

        So 1.5V dropped at 25mA is 37.5mW wasted power whether it is dropped
        in a resistor or a transistor.

        The way to get less power loss is to use a switching regulator. But I
        suspect it will be beyond your current skills, something for a future
        project.

        Steve Greenfield

        --- In Electronics_ 101@yahoogroups. com, terramir <terramir@.. .> wrote:
        >
        > well I actually solved my own resistor heat problem, I soldered the
        resistors between the + & - side of one of the battery spaces lowering
        the start voltage to 4.5V which is much closer to the 3.2-3.2 forward
        voltage. hence wasting less energy on heat production simple solution
        to a problem I coul;d have made much more complex.
        > Problem solved ty for your guys input though, I might use those
        solutions later for other lights, cause the seem a bit more elegant
        and even more power saving in the end.
        > terramir
        >















        [Non-text portions of this message have been removed]
      • jverive
        Did you solder resistors directly across the + and - battery rails, effectively lowering the battery voltage? This method depends on the internal resistance to
        Message 3 of 5 , Sep 1 1:48 PM
        • 0 Attachment
          Did you solder resistors directly across the + and - battery rails, effectively lowering the battery voltage? This method depends on the internal resistance to give the necessary voltage. Unfortunately, the battery's internal resistance increases as the battery is being used (due to heat and chemical reactions). In addition, ANY solution that relies on simple DC voltage and/or current limiting will waste the same amount of power (usually in the form of heat).

          So, if your solution works to your satisfaction, congratulations may well be in order. Nonetheless, you didn't solve your initial problem of wasted power/heat.

          Jeff Verive

          --- In Electronics_101@yahoogroups.com, terramir <terramir@...> wrote:
          >
          > well I actually solved my own resistor heat problem, I soldered the resistors between the + & - side of one of the battery spaces lowering the start voltage to 4.5V which is much closer to the 3.2-3.2 forward voltage. hence wasting less energy on heat production simple solution to a problem I coul;d have made much more complex.
          > Problem solved ty for your guys input though, I might use those solutions later for other lights, cause the seem a bit more elegant and even more power saving in the end.

          --- In Electronics_101@yahoogroups.com, terramir <terramir@...> wrote:
          >
          > well I actually solved my own resistor heat problem, I soldered the resistors between the + & - side of one of the battery spaces lowering the start voltage to 4.5V which is much closer to the 3.2-3.2 forward voltage. hence wasting less energy on heat production simple solution to a problem I coul;d have made much more complex.
          > Problem solved ty for your guys input though, I might use those solutions later for other lights, cause the seem a bit more elegant and even more power saving in the end.
          > terramir
          >
        • terramir
          No I soldered the resistors in place of a 4th battery in series. and I approximatly reduced the losses by 50% because a diode with a forward voltage around 3
          Message 4 of 5 , Sep 1 9:52 PM
          • 0 Attachment
            No I soldered the resistors in place of a 4th battery in series. and I approximatly reduced the losses by 50% because a diode with a forward voltage around 3 volts  means the resistor has "use" about 1.5V @ 110mA instead of 3V@ 110mA so the loss is effectively halved however as the voltage drops they will have to reduce the resistance in order to maintain a workable voltage that's why I paralleled a resistor in series with a pot for them to be able to reduce the resistance without going over the effective limits. it's by far5 not optimal however fitting a boost circuit in there and put the LED's in series is right now beyond my miniatursation skills and would have cost more than I was willing to spend at the current moment.
            terramir
             
             
            From: jverive <jverive@...>
            Subject: [Electronics_101] Re: 6V lamp and led's solved by lowering to 3 AA
            To: Electronics_101@yahoogroups.com
            Date: Monday, September 1, 2008, 1:48 PM






            Did you solder resistors directly across the + and - battery rails, effectively lowering the battery voltage? This method depends on the internal resistance to give the necessary voltage. Unfortunately, the battery's internal resistance increases as the battery is being used (due to heat and chemical reactions). In addition, ANY solution that relies on simple DC voltage and/or current limiting will waste the same amount of power (usually in the form of heat).

            So, if your solution works to your satisfaction, congratulations may well be in order. Nonetheless, you didn't solve your initial problem of wasted power/heat.

            Jeff Verive

            --- In Electronics_ 101@yahoogroups. com, terramir <terramir@.. .> wrote:
            >
            > well I actually solved my own resistor heat problem, I soldered the resistors between the + & - side of one of the battery spaces lowering the start voltage to 4.5V which is much closer to the 3.2-3.2 forward voltage. hence wasting less energy on heat production simple solution to a problem I coul;d have made much more complex.
            > Problem solved ty for your guys input though, I might use those solutions later for other lights, cause the seem a bit more elegant and even more power saving in the end.

            --- In Electronics_ 101@yahoogroups. com, terramir <terramir@.. .> wrote:
            >
            > well I actually solved my own resistor heat problem, I soldered the resistors between the + & - side of one of the battery spaces lowering the start voltage to 4.5V which is much closer to the 3.2-3.2 forward voltage. hence wasting less energy on heat production simple solution to a problem I coul;d have made much more complex.
            > Problem solved ty for your guys input though, I might use those solutions later for other lights, cause the seem a bit more elegant and even more power saving in the end.
            > terramir
            >















            [Non-text portions of this message have been removed]
          Your message has been successfully submitted and would be delivered to recipients shortly.