RC India

hello all,

i have 2 micro servos which can work on max 4.2v (didn't saw that while ordering) but my reciever is gives 5v  :-\

when i used one servo in one channel (each for rudder and elevator) it overheats and its housing melts
(replaced those with 5v ones)

But i cant replace aileron ones(though using both servos on same channel using y cable)
and they are still heating but not as much as single servo was heating.

I want to ask if there is a way i can use these servos ???

Which servos are you using? Please post a link.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=17540 (http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=17540)  :-\

You can, you need to do some DIY though.

Get a 7803, 3v voltage regulator IC and connect the positive(+) and ground(-) lines of the servos to the 7804's output and the signal line has to be directly given to the Rx.
The 7803 will be powered by the BEC 5v, if the VR heats up too much, put a heat sink.

You could try a 7804 too, but I reckon a 7803 is safer because your servo is rated to work in between 2.8v and 4.2v and a typical 78xx has about 1-2mV tolerance. You'll never risk going over 4.2v and frying the srvo.

If you need a schematic, I can prep one.  :thumbsup:

Thanks mate
I also thought about it
Just looking for an approval

Thank you

You can put 4 nos 1N4007 Diode in series to drop out 4x.4 =1.6 volt to 4x.6=2.4 volt from 5 volt (resulting an output of 3.4 volt to 2.6 volt). You can connect 4 diode initially and then can reduce one by one to get performance. It will be easier and need no heat-sink as well as perfect performance and lower weight. You can also file out some ceramic package to reduce further weight (For ultra light electronics, but I think not required, Just using short lead is enough.) Again this diode circuit will not consume extra power. 78XX needs 2.5-3 volt excess than output for it's performance. So from 5 volt to 3 volt using 78XX is not an good idea from my viewpoint.

Sig--------------|>|---|>|---|>|--|>|-----------  \
                                                                       /
Positive----------|>|---|>|---|>|--|>|----------- >   Servo end
                                                                       \
Negative ----------------------------------------  /

Awesome idea Kalyan da!  :bow:
We just tend to jump to voltage regulators in such situations.

Kalyan da thank you and you will be glad to know that i actually used diode solution
I was searching for voltage regulator in my component box when i saw strip of 1N4007 diodes  :P

Then i thought how silly i am forgetting the basics of electronics  :giggle:

Oh, nice to hear from u harsh... Good luck.

Could zener diodes help ?

Zeners cannot be used.Zener diodes are typically used for low power applications which use a current of few mA not more than 100mA and varies with model number.

What about using a voltage dropper with two resistors ?

Unfortunately they are just designed to for variable voltage purpose but cannot drive large current. If you take a 10k pot for example and adjust such that it will give 4v output with 5v input . Now let 1A current flows through it then voltage drop will be (2k*1A)=2000v which is not possible moreover there are many factors sch as power dissipation also so potential divider n/w are just for reference purpose better use a regulator only.