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Help! Receiver only has 1.5 volt where 5 volts should be...

#1
Question... What if my receiver is only sending 1.5volts to the servos? It is a Hubsan flight controller and receiver in one unit. Have you ever heard of this? Thank you!

I have a DX8 transmitter and spektrum receivers on my own projects but I was just salvaging parts from a Hubsan RTF airplane to give to a kid.
 

FDS

Well-known member
#2
If it only powered little linear actuator type servos then be aware it might not have the power for larger ones.
Drone controllers don’t have a PWM output for servos usually.
If it was a Heli one then it might not be sending the full 5v if the servos are at rest. Servos draw power to move the arm and hold it in position, centred is their idle position.
 
#3
If it only powered little linear actuator type servos then be aware it might not have the power for larger ones.
Drone controllers don’t have a PWM output for servos usually.
If it was a Heli one then it might not be sending the full 5v if the servos are at rest. Servos draw power to move the arm and hold it in position, centred is their idle position.
Thanks for the reply! Do you think this is a drone controller? This receiver was sourced from a Hubsan airplane (H301s Spy Hawk) but you might be right, this might be a drone controller. Here is a picture of it.
The reason I wanted to source the electronics out of this RC is because it has Stabilization, 5.8ghz FPV, GPS Return to home, telemetry and a lot more at an inexpensive entry rate, especially for beginners.

Point being... Has anyone heard of 1.5v servos? Or does anyone think that I need to splice in separate 5v power to run the servos and ESC if the PWM is good from the receiver. Is this a common problem?
 

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FDS

Well-known member
#4
That should run regular servos, just not huge metal gear digital ones.
At what point did you measure the output voltage? Was the system just sat connected to the TX or were you putting in stick commands? At rest it won’t send more than signal voltage. Motors of any kind draw 0v off, servo signal voltage is just there to stop the control surface moving off centre. It’s a flight controller for FPV aircraft, not a quad controller. Looks like it might be useful, you will need a GPS antenna and you will have to calibrate it I suspect if you want return to home etc.
You don’t need any of those features for a beginner. Low rates and a bit of expo will be all you would need.
 
#6
That should run regular servos, just not huge metal gear digital ones.
At what point did you measure the output voltage? Was the system just sat connected to the TX or were you putting in stick commands? At rest it won’t send more than signal voltage. Motors of any kind draw 0v off, servo signal voltage is just there to stop the control surface moving off centre. It’s a flight controller for FPV aircraft, not a quad controller. Looks like it might be useful, you will need a GPS antenna and you will have to calibrate it I suspect if you want return to home etc.
You don’t need any of those features for a beginner. Low rates and a bit of expo will be all you would need.
Lol, Of course you don't "need" Stabilization and RTH etc... but It has it, so why not keep it!?

As for the GPS, it comes with all that, the GPS module, Compass Module, Camera 5.8TX, telemetry, etc... all for $40. If I can get this to work This would be phenomenal to put in all my planes.

So, I measured the middle of the 3 wires with the receiver battery and system plugged in. My spektrums usually measure 5v, this one measured 1.5v. Then i measured the "S" side of the 3 wires and it measured 1.5v at rest as well as 1.5v at 100% on the transmitter, which is correct, right? Because its the pulse rate of that 1.5v that matters? So, why would the constant power be 1.5v? Are there servos in the RC industry that run on 1.5v? I contacted Hubsan with no answer yet.
 

FDS

Well-known member
#8
No idea about that. What was in the original plane?
I have to admit to not measuring my servo voltages, I would guess the signal voltage would vary and the 5v rail would be the constant. Thankfully it’s not something I have had to worry about, so I can learn from this thread too.
Sitting back, waiting for a clever person....
 

DamoRC

Well-known member
Mentor
#9
What battery / BEC are you powering the unit with and what voltage is being output to the controller (measuring before you connect to the FC). I would think that these are 5V in, 5V out. Also, do you know why it has 2 JST inputs, is the second just a daisy chain connector
 

DamoRC

Well-known member
Mentor
#10
Based on this article the longer JST is for your battery and the shorter is to power your esc. In this configuration I would think it has its own voltage regulator. So it needs 2S in on the battery JST. Is this how you are powering it?