5 Volt regulator

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" colspan=2 height=82 BGCOLOR="#006699" TEXT="#080000"> <div> <FONT SIZE="5" COLOR="#FFFFFF" FACE="Arial" ><B>JBVM Delemarre</B></FONT><B>     |     </B><A HREF="id49.htm" TARGET="_top" TITLE="This is the English part of my home page"><U><B>home</B></U></A></div> <div> <B>5 Volt regulator</B>   |   <A HREF="id42.htm" TARGET="_top" TITLE="Schematic with description of 5 volt reg"><U>Schematic with description of 5 volt regulator</U></A>   |   <A HREF="id43.htm" TARGET="_top" TITLE="PCB for 5 volt regulator"><U>PCB for 5 volt regulator</U></A>   |   <A HREF="id44.htm" TARGET="_top" TITLE="Component placement 5 volt regulator und"><U>Component placement 5 volt regulator underside </U></A>   |   <A HREF="id45.htm" TARGET="_top" TITLE="Component placement 5 volt regulator top"><U>Component placement 5 volt regulator topside</U></A>   |   <A HREF="id46.htm" TARGET="_top" TITLE="Components list 5 volt regulator"><U>Components list 5 volt regulator</U></A>   |   <A HREF="id47.htm" TARGET="_top" TITLE="Photos of 5 volt regulator"><U>Photo's of 5 volt regulator</U></A></div> <div> </div> </td> </tr><tr> <td valign="top" width=210 BGCOLOR="#FFCC66" TEXT="#080000"> <div> A voltage regulator on board of model airplanes reduces the risk of electrical failure.</div> <div> The regulator as described is usable for all the radio control sets known to me.</div> <div> Information to build this regulator is provided together with pictures of the one build by me.</div> <div> Questions? <A HREF="mailto: delemarre@cistron.nl" TARGET="_top" TITLE="mailto: delemarre@cistron.nl"><U>Send a mail</U></A><A HREF="mailto: delemarre@cistron.nl" TARGET="_top" TITLE="mailto: delemarre@cistron.nl"><U>!</U></A></div> <bR> <div> <A HREF="id49.htm" TARGET="_top" TITLE="This is the English part of my home page"><U>Home</U></A></div> <bR> <div> <A HREF="id42.htm" TARGET="_top" TITLE="Schematic with description of 5 volt reg"><U>Schematic with description of 5 volt regulator</U></A></div> <bR> <div> <A HREF="id47.htm" TARGET="_top" TITLE="Photos of 5 volt regulator"><U>Photo's</U></A></div> </td> <td valign="top" height=398 BGCOLOR="#FFFFFF" TEXT="#080000"> <div> <I>5 Volt regulator</I></div> <div> The power supply on board of model airplanes remains a good topic for discussion. Batteries with increasing capacities are being used but usually we don't fly any longer during a flying session than we used to do about twenty years ago when everybody used a 500mAh NiCad pack. Today 1700 mAh SANYO nicads are frequently used as the receiver pack. The question remains if the increase in capacity (and thus weight!) makes any sense. The voltage doesn't increase and the incomplete discharge can lead to the dreaded "memory effect". When asked for the reason to increase NiCad capacity the feeling of safety is is frequently mentioned because the increase in capacity will prevent the disfunction of the receiver and servo's caused by the lack of electrical power. However this lack of power is not prevented  by a mere increase in capacity. What we want is a <I><B>constant and stable voltage</B></I><B> </B>to the receiver and servo's. Multiplex solved this in the DS12 receiver by providing a possibility to use a separate battery for the servo's by placing a programming connector in one of the output ports for servo's on the receiver and then using an other battery for the receiver itself. With this option the receiver is not influenced by the voltage fluctuations on the supply rails caused by the servo's when they draw a heavy current.</div> <div> These high currents are more common than one tends to believe especially when using digital servo's! High currents cause a drop in voltage along the supply line wiring while the NiCad itself also shows some decrease in output voltage due to its internal resistance. </div> <div> In order to get some impression about the supply voltage on board of a "just for fun" model airplane some investigations were done using a volt meter that registered the highest-, the lowest-, the mean- and the actual supply voltage during a flight. The current consumption during the test flights was also measured. </div> <div> A "Data Logging Receiver Supply Voltage Monitor" by <A HREF="http://www.omegaco.demon.co.uk/mechome.htm" TARGET="_top" TITLE="http://www.omegaco.demon.co.uk/mechome.h"><U>Martin Barratt</U></A> and a "used current" meter by Milan Lulic as described in the German magazine "Modell" were build and used to this end. The "used current" meter is obtainable from Conrad Electronics and they will send the kit to you by mail order (order no. 11 60 50-99).</div> <div> The airplane is a Goldberg Piper Cub with a .52 FS OS engine, 2 Multiplex MC servo's (digital) and two standard servo's and a dual conversion PCM receiver, with a gyro on rudder during take of.</div> <div> Measurements were done in several flights of 12 to 15 minutes during which time continuous control input was given to at least two servo's and frequently three. (A rather twitchy flight envelope was the result, but for science everything is allowed...) </div> <div> Two things became apparent to me: The <I><B>capacity used</B></I> from the NiCads was much <I><B>less</B></I> than expected and the <I><B>drops in voltage </B></I>were <I><B>much higher</B></I> than I expected.</div> <div> During one hour flying time 250 to 300 mAh was used from the NiCad's and the voltage measured on the receiver outputs to the servo's varied between 5.2 and 4.4 volt <I><B>while using a freshly charged</B></I> 1700 mAh SANYO NiCad with four cells. The drops in voltage last for a very short time, up to 120 milliseconds when two digital servo's start to react at the same time or when one servo is pulling hard, but they can lead to a malfunction of the microprocessor in the receiver leading to short "interferences".</div> <div> Measurements with batteries of various capacities did not show any difference! The voltage drops are caused by the resistance in the wires, switch, connectors and the high current used by the servo's. </div> <div> Next I tried what a stabilized voltage and a five cell NiCad would bring. A so called low drop regulator was used able to supply a five ampere current with a minimal drop of only 0.370 volts on the supply voltage. In order to minimize the influence of the resistance in the wires double leads from the NiCad to the regulator were used. The regulator used has another advantage. The switch is no longer in the current carrying circuit and can therefor no longer contribute to failures and voltage losses!</div> <div> Measurements with this system showed a maximum voltage drop of 0.1 volts on the supply rails at the receiver during maximum load! The voltage supplied to the receiver is 5.034 volts and the maximum drop measured was 0.1 volts to 4.9 volts.</div> <div> The battery I use today has a capacity of 1250mAh and is made of five cells. These are SCRL cells by SANYO and can be fast charged.</div> <div> On the following pages a simple electronic circuit, a layout for a printed circuit board, and pictures of my example are shown. Because surface mounted devices are being used some experience with fine soldering work is essential to succeed in making one for yourself. Otherwise consult your local whiz kid with the hot iron and ask him to help you out!!</div> <div> On the <A HREF="id65.htm" TARGET="_top" TITLE="Downloadable files"><U>download page</U></A> you can find the program to make a print of the layout with the files to do so. When you only get a print of the five holes for the regulator, the second print layer is not activated. To do this highlight the number "two" in the lower right screen part of the easylase program so it appears the same as number "one"</div> <bR> <bR> <bR> </td> </tr></table></body>