Reading R/C receiver pulses using the scope

[engB]

Hi Everyone,
I am trying to see the pulses of an R/C receiver in the oscilliscope. I have connected the two wires of the scope to the blck and the white wires of channel-1 in the reciever but still not getting any pulse even when I incease the speed or decrease it in the transmitter. does any body have an idea.
thanks
engB

[dyarker]

Receiver has battery, and is turned on??<p>Sweep speed of o'scope slow enough??<p>O'scope set to auto trigger or free run??<p>Pull up resistor if receiver output is open collector???

[NutVolt]

Try using a rf sniffer on your scope and move it around the chips.
It may pickup some rf from the chips in the receiver.
I used this on the transmitter to adjust the pulses by touching the
top of each chip until I got a wave pattern.

nut

[philba]

First, plug in a real servo and see if it works.

Most servos use a 3 wire connection, +V, gnd and signal. You want to connect to signal and ground. Different servos have different connector color schemes. Futaba uses white/red/black. Usually the connector has the center pin for +V so you want the other two pins. Black is usually ground (but it wont hurt to connect the scope probe/gnd backwards. Set your scope to 20 mS sweep time and you should see a pulse that varies between 1 and 2 mS in width. make sure you are triggering on channel 1.

It is also possible that the receiver needs a load on the servo.