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Re: Voltage regulator circuit

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  • Kerim F
    I think it is better adding a suitable resistor also in series with the 3 diodes in order to drop a few hundredth mV. Its value depends on the load current.
    Message 1 of 19 , Jul 15, 2013
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      I think it is better adding a suitable resistor also in series with the 3 diodes in order to drop a few hundredth mV. Its value depends on the load current.


      --- In Electronics_101@yahoogroups.com, "laser100" <laser100@...> wrote:
      >
      > Input is 8.4V at full charge. Receiver will manage around 6V. Maybe three diodes will work. That way there won't be a drain right? Thanks
      >
      > --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@> wrote:
      > >
      > >
      > >
      > > --- In Electronics_101@yahoogroups.com, "laser100" <laser100@> wrote:
      > > >
      > > > I put together this circuit so I could use a 7.4V LiPo to power the receiver on one of my RC gliders. The servos will only handle up to about 5.5V. It seems like when the circuit is disconnected from the receiver it still drains the battery down. Does this voltage regulator chip actually put a load on the battery. the capacitors couldn't be doing it could they? Thanks for your input. I uploaded the circuit, file is called VoltRegRC.jpeg
      > > >
      > >
      > > Perhaps, since I have no sure idea about the max/min voltages expected on battery and allowed for the load, placing 3 diodes in series can likely do the job ;)
      > >
      >
    • AlienRelics
      These all sound like extraordinarily bad ideas. Voltage will change with current draw. You are turning off the radio, right? So put in a 5V regulator and put
      Message 2 of 19 , Jul 16, 2013
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        These all sound like extraordinarily bad ideas. Voltage will change with current draw.

        You are turning off the radio, right? So put in a 5V regulator and put the switch at the battery before the regulator.

        There are plenty of low dropout 5V regulators out there. Or you could use a more efficient switching regulator such as the MC34063.

        Here is a design tool, you can enter the input voltage, percent variation, and desired output voltage and maximum current.

        http://dics.voicecontrol.ro/tutorials/mc34063/

        Just about every little cigarette lighter charger has this IC in it. The Dollar Tree had some cigarette lighter to USB that have all the parts you need, and an inductor that can be rewound if necessary. For a buck. Change a resistor or two and the inductor, and away you go.

        It can turn 6 to 9V into 5V at 500mA.

        Calculation Results For Step-Down Converter

        Vin = 7.40 ±20% V
        Vout = 5.00 V
        Iout = 0.50 A
        Vripple = 0.10 V

        Vin min = 5.92 V
        Ton / Toff = 12.86
        Ton + Toff = 10.00 µs (micro seconds)
        Toff = 0.72 µs (micro seconds)
        Ton = 9.28 µs (micro seconds)
        Ct = 371.13 pF
        Ipk = 1.00 A
        Rsc = 0.30 Ω
        Lmin = 3.90 µH
        Co = 12.50 µF
        R1 = 10.00 kΩ
        R2 = ((Vout - 1.25) / 1.25) * R1= 30.00 kΩ

        Steve Greenfield AE7HD


        --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@...> wrote:
        >
        > I think it is better adding a suitable resistor also in series with the 3 diodes in order to drop a few hundredth mV. Its value depends on the load current.
        >
        >
        > --- In Electronics_101@yahoogroups.com, "laser100" <laser100@> wrote:
        > >
        > > Input is 8.4V at full charge. Receiver will manage around 6V. Maybe three diodes will work. That way there won't be a drain right? Thanks
        > >
        > > --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@> wrote:
        > > >
        > > >
        > > >
        > > > --- In Electronics_101@yahoogroups.com, "laser100" <laser100@> wrote:
        > > > >
        > > > > I put together this circuit so I could use a 7.4V LiPo to power the receiver on one of my RC gliders. The servos will only handle up to about 5.5V. It seems like when the circuit is disconnected from the receiver it still drains the battery down. Does this voltage regulator chip actually put a load on the battery. the capacitors couldn't be doing it could they? Thanks for your input. I uploaded the circuit, file is called VoltRegRC.jpeg
        > > > >
        > > >
        > > > Perhaps, since I have no sure idea about the max/min voltages expected on battery and allowed for the load, placing 3 diodes in series can likely do the job ;)
        > > >
        > >
        >
      • CharlesW
        After reading others comments, it does seem easier to just put an ordinary regulator on the receiver side of the disconnect, if that s practical. The
        Message 3 of 19 , Jul 16, 2013
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          After reading others' comments, it does seem easier to just put an ordinary regulator on the receiver side of the disconnect, if that's practical. The micro-power regulator makes sense if the regulator can't be on the receiver side of the connection and will therefore be under power all the time.
        • Ron Wright, N9EE
          I ve used a few diodes to drop voltage and it works well. Diodes do vary their voltage drop with changing current a little, but in this case not a problem.
          Message 4 of 19 , Jul 17, 2013
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            I've used a few diodes to drop voltage and it works well. Diodes do vary their voltage drop with changing current a little, but in this case not a problem. And would be real simple, 3 1N4001s that can handle 1A, much more than the rcvr would need.

            Only problem the diodes will have fixed voltage drop so as battery discharges so will the rcvr voltage...will always be about 1.8V less than the battery.

            When disconnected there will be no current draw as stated in another post.

            73, ron, n9ee/r

            --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@...> wrote:
            >
            > I think it is better adding a suitable resistor also in series with the 3 diodes in order to drop a few hundredth mV. Its value depends on the load current.
            >
            >
            > --- In Electronics_101@yahoogroups.com, "laser100" <laser100@> wrote:
            > >
            > > Input is 8.4V at full charge. Receiver will manage around 6V. Maybe three diodes will work. That way there won't be a drain right? Thanks
            > >
            > > --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@> wrote:
            > > >
            > > >
            > > >
            > > > --- In Electronics_101@yahoogroups.com, "laser100" <laser100@> wrote:
            > > > >
            > > > > I put together this circuit so I could use a 7.4V LiPo to power the receiver on one of my RC gliders. The servos will only handle up to about 5.5V. It seems like when the circuit is disconnected from the receiver it still drains the battery down. Does this voltage regulator chip actually put a load on the battery. the capacitors couldn't be doing it could they? Thanks for your input. I uploaded the circuit, file is called VoltRegRC.jpeg
            > > > >
            > > >
            > > > Perhaps, since I have no sure idea about the max/min voltages expected on battery and allowed for the load, placing 3 diodes in series can likely do the job ;)
            > > >
            > >
            >
          • Jan Kok
            Still haven t seen a reply to my question: Why is the idle current [of the voltage regulator] a big deal? Can t you just put a switch in series with the
            Message 5 of 19 , Jul 17, 2013
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              Still haven't seen a reply to my question:

              Why is the idle current [of the voltage regulator] a big deal? Can't you
              just put a switch in series with the battery, or just unplug the battery
              when not in use?


              [Non-text portions of this message have been removed]
            • Kerim F
              ... I don t think there is a switch in the first place.
              Message 6 of 19 , Jul 17, 2013
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                --- In Electronics_101@yahoogroups.com, Jan Kok <jan.kok.5y@...> wrote:
                >
                > Still haven't seen a reply to my question:
                >
                > Why is the idle current [of the voltage regulator] a big deal? Can't you
                > just put a switch in series with the battery, or just unplug the battery
                > when not in use?
                >
                >
                > [Non-text portions of this message have been removed]
                >

                I don't think there is a switch in the first place.
              • AlienRelics
                ... Well, then, the receiver is going to run down the battery. Steve Greenfield AE7HD
                Message 7 of 19 , Jul 17, 2013
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                  --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@...> wrote:
                  >
                  > --- In Electronics_101@yahoogroups.com, Jan Kok <jan.kok.5y@> wrote:
                  > >
                  > > Still haven't seen a reply to my question:
                  > >
                  > > Why is the idle current [of the voltage regulator] a big deal? Can't you
                  > > just put a switch in series with the battery, or just unplug the battery
                  > > when not in use?

                  > I don't think there is a switch in the first place.

                  Well, then, the receiver is going to run down the battery.

                  Steve Greenfield AE7HD
                • Kerim F
                  ... You are right Steve if the load current cannot be cut off by an already available switch or alike. Kerim
                  Message 8 of 19 , Jul 17, 2013
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                    --- In Electronics_101@yahoogroups.com, "AlienRelics" <alienrelics@...> wrote:
                    >
                    > --- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@> wrote:
                    > >
                    > > --- In Electronics_101@yahoogroups.com, Jan Kok <jan.kok.5y@> wrote:
                    > > >
                    > > > Still haven't seen a reply to my question:
                    > > >
                    > > > Why is the idle current [of the voltage regulator] a big deal? Can't you
                    > > > just put a switch in series with the battery, or just unplug the battery
                    > > > when not in use?
                    >
                    > > I don't think there is a switch in the first place.
                    >
                    > Well, then, the receiver is going to run down the battery.
                    >
                    > Steve Greenfield AE7HD
                    >

                    You are right Steve if the load current cannot be cut off by an already available switch or alike.

                    Kerim
                  • laser100
                    Thanks for all you help. I had soldered the battery to the voltage regulator and was plugging the regulator into the receiver when I would use it. I didn t
                    Message 9 of 19 , Aug 8, 2013
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                      Thanks for all you help. I had soldered the battery to the voltage regulator and was plugging the regulator into the receiver when I would use it. I didn't realize about there would be a current drain if it wasn't connected to the receiver. I modified it and put the switch between battery and voltage regulator. All is good. Thank you all again.

                      --- In Electronics_101@yahoogroups.com, Jan Kok <jan.kok.5y@...> wrote:
                      >
                      > Put a 1 ohm resistor in series with the battery and measure voltage across
                      > it to determine the idle current draw?
                      >
                      > Why is the idle current a big deal? Can't you just put a switch in series
                      > with the battery, or just unplug the battery when not in use?
                      >
                      >
                      >
                      > On Sun, Jul 14, 2013 at 7:10 PM, laser100 <laser100@...> wrote:
                      >
                      > > Voltage went from 8.4V to 7.75V in about 12 hours.
                      > >
                      > > --- In Electronics_101@yahoogroups.com, "laser100" <laser100@> wrote:
                      > > >
                      > > > I put together this circuit so I could use a 7.4V LiPo to power the
                      > > receiver on one of my RC gliders. The servos will only handle up to about
                      > > 5.5V. It seems like when the circuit is disconnected from the receiver it
                      > > still drains the battery down. Does this voltage regulator chip actually
                      > > put a load on the battery. the capacitors couldn't be doing it could they?
                      > > Thanks for your input. I uploaded the circuit, file is called VoltRegRC.jpeg
                      > > >
                      > >
                      > >
                      > >
                      > >
                      > > ------------------------------------
                      > >
                      > > Please trim excess when replyingYahoo! Groups Links
                      > >
                      > >
                      > >
                      > >
                      >
                      >
                      > [Non-text portions of this message have been removed]
                      >
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