OK. I just wanted to be sure
OK. I just wanted to be sure of your connections before we all started troubleshooting the wrong things.</p>
Try the pulldown resistors and let us know what happens.
how do you mean "and the
…
Also be sure that the metal
Also be sure that the metal housing of the motors and transistors do not touch each other…
I can’t find out how to
I can’t find out how to attach a new schematic of the adjustments of the circuit, but I added the 10K resistors from base to ground.
To eliminate the battery, I tied both emitters to ground, and the terminal from the motor that is not attached to the collector to +12V
Again, both motors run
It is acting like I have the motors in parallel
I wanna know sure…
I wanna know sure is it’s something with the receiver (thats works maybe different then we all think) or if it’s something with the transistors…
try this: Disconnect the whole receiver, so only the 4 wires are left over. then connect one of the bases (WITH the 1K resistor between!!) to the + of the battery. what happens? are they still both turning?
That’s a good
That’s a good troubleshooting approach. Make sure when you disconnect the receiver that you leave the pulldown resistors in place so the disconnected wires don’t float high.
Using the schematic that
Using the schematic that shows both motors connected 1 battery, disconnecting the receiver, leaving the 10K resistors from the base to ground. I connected the + from the base through the 1K resistor, and only one motor ran.
Then connecting the + from the base through the other 1K resistor, the other motor ran. They both did not run in either case.
So it sounds like the
This is progress. It sounds like the transistors are working fine. It is something with your receiver itself, or with the wiring to your receiver.
Double-check your connections with a multimeter. See if there is a short between your receiver outputs while it is disconnected from the transistors. If you find no short, re-connect it and check for a short between the receiver outputs again.
Also try disconnecting your receiver and testing the outputs while you send commands from your transmitter. Verify that receiver output 2 is inactive when you are only commanding output 1 to turn on, and vice-versa.
Here are the readings I am
Here are the readings I am getting from my meter with the 4 wires disconnected from the receiver to the circuit.
From the receiver there is a battery connection, and additionally two red wires, a yellow wire and a blue wire.
I connected the battery, thenI attached my meter from 1 red wire to the yellow wire, when I turned the left control stick on the transmitter (that would run both motors), the voltage would be around 5.16V. Then turning the right control stick on the transmitter (that would run one motor), in one direction, the voltage reading was 5.06V, then turning the right control stick on the transmitter the opposite direction, the voltage was 0.
Then I attached the same red wire to the blue wire, and followed exactly the same procedure. The left control stick (for both motors) was the same around 5.16V. However when turning the right control stick on the transmitter (that would run one motor), I got just the opposite results as I did before, as anticipated.
Then, using the other red wire, I followed the same procedure and got the same results.
I hope this is helpful.
** what are you meassuring**
what are you meassuring between the - and the red wire? does it stay at 0 volt?
Sorry, maybe I’m a bit slow
Sorry, maybe I’m a bit slow this morning. I’m having trouble understanding your description.
Maybe a picture of your actual receiver and transmitter would help. Or model numbers so we can look them up.
My limited experience with RC receivers is that each channel has a three pin connection (power, ground, signal), typically used for running a servo. There’s sometimes a separate three pin connector that lets you connect power and ground input for the receiver, but I’ve also seen some where you use one of the servo connectors to provide power and ground for the receiver itself too.
Your drawing is very different from the above. It would help to understand what your equipment is.
** what are you meassuring**
I almost think the red wires are constant +, could you check this?
If so…it explains all: The motors then are controlled by switching the negative wire. This explains why they both run when connecting to 1 battery. In that case you should need PNP transistors instead of the NPN you’re using now with a slightly different circuit.
When I have the receiver off
When I have the receiver off or on it measure 5V on both red wires.
I get nothing on the blue or yellow wire.
I am measuring from the battery ground on the 6V unit that powers the receiver, to the red, blue and yellow wires.
What I have is called a
What I have is called a yellow bee RC airplane, they are sold though Harbor Freight.
They are a cheapie.
It uses an airplane transmitter with a control stick on the left that moves up and down. The movement up does nothing but when you move the stick toward you (down) then both small motors run.
On the right of the transmitter a control stick moves to the right and left. Moving the stick to the right, will operate the right motor. Moving the stick to the left, will operate the left motor.
When I dismantled the receiver and motors, from the airplane, the receiver has two wires going to each motor. A red wire, and a blue wire to one motor, and a red wire and a yellow wire to the other motor. It has a 6V battery pack (using 4 recharageable AA batteries in a shrink wrap, I would guess) to power the receiver and the 2 small motors.
I saw on the RC airplane site how make an esc to control one motor (www.rc-airplane-advisor.com/electronic-speed-controller.html)
It was using a servo motor amp board. Since this airplane receiver did not have a servo motor amp board, I just tried to modify it to work for my larger motors and using 12V.
Finally, I discovered that by using the schematic that I posted originally, I could get it to operate either motor independently, or both at the same time if I used 2 power sources. Thus coming up with the schematic. This circuit does work, but I am simply trying to eliminate one battery if possible.
If I measure either red
If I measure either red wire, from ground, they are both reading approx 5V whether the receiver is turned on or off.
OK, so it sounds like Dannyv
OK, so it sounds like Dannyv is correct, and the red wires are just 5V power and are on all the time. So the yellow and blue wires are your signal that you need your circuit to respond to.
Measuring from the receiver ground for all measurements, can you tell us the voltage on:
- yellow wire when the receiver is off
- yellow wire with the receiver on and the control in neutral position
- yellow wire with the receiver on and the control in the “on” position
- blue wire when the receiver is off
- blue wire with the receiver on and the control in neutral position
- blue wire with the receiver on and the control in the “on” position
Assuming the yellow and blue are your signal outputs for channel 1 and channel two, if they are active high, you should see them at about 5V when you command them “on”, If they are active low, you should seem them at about 0V when you command them on.
Assuming they are active high, your circuit will work when you make the following connection changes:
- Disconnect both red wires. You don’t need them
- Disconnect the yellow wire from the emitter and 12v battery ground; connect it to the input of the base resistor.
- Disconnect the blue wire from the emitter and 12v battery ground; connect it to the input of the base resistor.
If your signal wires are actually active low, you will need to replace your transistors with PNP style components.
Here are the results:With
Here are the results:
With my black lead on my meter to 6V ground:
Yellow reads .02V with receiver off or on. It makes no difference.
Blue reads .01V with receiver off or on. It also makes no difference.
Yellow wire when throttle that runs both motors is on 0V, When left stick is on .02V When right stick is on -.09V
Blue wire when throttle that runs both motors is on 0V, When left stick is on -.09V When right stick is on .02V
** meassure now with one wire**
meassure now with one wire of your meter on the +…
Now with my red lead of my
Now with my red lead of my meter on the + battery terminal, here are the results:
When the receiver is off and the black lead of my meter attached to either the blue, yellow, or 2 reds, I get 0V
When the receiver is on and the black lead of my meter attached to either the blue, yellow, or 2 reds, I also get 0V.
With the transmitter turned on and in neutral, and the receiver is on, I get 0V on each of the wires as well.
With the transmitter turned on and the stick that controls both motors is on, I get 0V on both reds, and I get 4.98V on both the blue and yellow wires.
With the transmitter turned on the the stick that controls each motor independently is on, I get 0V on both reds, whether I turn the stick to the right or left. When I move the stick to the right I get 4.98V on the yellow wire and when I move the stick to the left I get 0V on the yellow wire. Conversly, when I move the stick to the left I get 4.98V on the blue wire and when I move the stick to th right I get 0V on the blue wire.
OK. So it sounds to me like
OK. So it sounds to me like your receiver provides an active LOW signal on the blue and yellow wires. You cannot trigger an NPN transistor with an active LOW signal.
You do have some choices.
- You can replace the current NPN power transistors with PNP power transistors
- You can keep the current NPN power transistors, but get a pair of small general purpose PNP transistors to drive them.
Option 2 looks like this:
Just about any general purpose PNP transitors should be OK. You are just using them to switch the power NPN transistors.
The 10k pull-down resistors keep the NPN transistors off, unless the general purpose PNP transistors are turned on by the active LOW signals from the yellow or red wires.