PT2272 RF

Hi there, im new here and new to ee design.

I just purchased a simple RF M4 Receiver 315 MHz momentary device:
https://www.adafruit.com/products/1096 and remote.

I have a small 5V DC motor connected to one of the 4 data pins. When i activate the pin (high) i get the correct 5V output, but the output isnt turning on the motor. I assume I'm doing this wrong. Im sure this comes down to some basic ee principals of design. I've attached a picture for reference. The pic doesnt show it but i have 5v on the rail.

Any help would be appreciated. Thanks!

Hey Ramien, I think this may be a simpler solution than what has been discussed so far. I imagine the problem is that your receiver can probably only source or sink something along the lines of 20mA, whereas your motor will draw 10 to 100 times that much current. Your receiver just can't give it enough power.

If you have a solid 5VDC supply that you're running your receiver on, you can just use an N-channel MOSFET as a switch. Connect the motor to 5V and the drain of the MOSFET, ground the source, and hook the gate of the FET to the output of your receiver. When the output of the receiver goes high, it should "close" the switch and allow the current to flow from 5V, through the motor, through the FET to ground.

Careful, though, as the motors can make your 5V source kind of dirty and may put out interfering EMI. Good luck!

Thank you Joshua. Is there a specific mosfet that i need for my application? I attached a list from NTE and there are tons to choose from. Which one is best? Thanks I appreciate your help.

Is this circuit design correct? Do i need a resistor inline?

Actually i think i made a mistake, motor should tie to 5v not ground, correct?

Ramien, the updated drawing that shows the motor being connected to 5V is correct, no resistor necessary. It should work as it is, though I would recommend looking into flyback diodes so you don't fry your receiver. I don't think the problem is the power supply, or at least that wouldn't be my first thought.

I don't know which MOSFET would be best for this application, there are a lot to choose from. The switching speed won't be important for this application as it won't be switching quickly. Just make sure that the Gate voltage is less than 5V and that the Drain to Source current can handle at least a couple Amps, probably 4 or 5 amps to be safe. So you're probably going to be looking into power FETs. See what you can find and post it here and I'll look at it and hopefully some other people with experience.

So here is my current schematic diagram 1 (1 power source). Everything is working, except the transceiver isn't communicating well with receiver - receiver problem. The Mosfet design was the right path. I also added a rectifier to prevent damage to motor.

Now, I want to run the receiver and moto off separate power sources but whenever I connect the motor to another source via diagram 2 attached, it doesn't work. Ideas?

Hey Ramien, that's getting closer. I realize that the schematic doesn't necessarily reflect the physical layout of the circuit, but I just want to emphasize that the Drain and the Source for the FET, where the current goes, needs to be connected to the battery, not the receiver.

Using the separate power supply, the problem is a lack of shared ground. Remember that voltage is all relative. Since you have two separate and unconnected power supplies, they're "floating" at different potentials. Easiest way to fix that is to attach ground on both supplies together, giving them the same reference as a basis. The problem with that is that the noise introduced to one power supply is transferred to the other.

Speaking of which, it's been awhile for me but I'm pretty sure that should be some sort of zener diode for the protection.

Yes good catch, I will update and show you the true diagram layout. Yes Zenner diode was used as I recall. I need to confirm the NTE# as the diagram I provided is not correct.