I would like to know if I can use a RFP30N06LE mosfet as a replacement for a relay. Say you have a +12v wire and you cut it in half and inserted the mosfet and used an arduino digital pin to switch it on and off. I'm pretty sure it can be done with negative on source and positive on drain or vice versa but not the way I need. Am I wrong or can I actually use it that way?
Why don't use a more appropriate part, a smart high side switch, like BTS432 or similar? The only problem can be the cost, but 'll save you a lot of headache.
Ciao, Ale.
I think you need to give the biiger picture, like what it is you are trying to control, the voltage/amps, high side/low side (prob high side for a relay), and well, ALL the details.
Yes you can use a mosfet, i have been doing that for a while now to control dc motors as a relay uses too much power and has no real control. All you need is a N channel mosfet and two resistors and possibly a reflecting diode if you're running an inductive load, fyi those few parts cost nothing, less than a average relay. you can use pwm or just a digital output to set a mean voltage or fixed on and off. And to that i can make the pcb same size or smaller using through holes components.
I have an arduino duemilanove, hc-05 Bluetooth, and a 4 channel relay module all wired up in the center of my 03' silverado and I'm using it for remote start. It works good but I have an issue with my relay module where one of the relays clicks on and off really fast multiple times completely randomly and I can't seem to figure out the problem with it. I noticed transistors or mosfets are popular for using as switches and 5 of those are smaller than the 4 relay module and I could solder them in where ever I wanted to conserve space that I don't have much of. I would also have the 5 switches that I could control individually instead of using one of the relays to give power to 2 wires at once and not having individual control. I have 2 ignition wires, 2 accessory wires, and a starter wire. I have soldered wires on them and I have my +12v wire that I use to power those 5 wires with the relays. I bought a pack of 5 rfp30n06le mosfets but I figured I would ask a simple question before I destroyed something. But it seems I should have asked before I bought them.
When comparing a relay to a Mosfet there are a number of significant differences. Some of them are:
- The relay is fully isolated between coil to contacts. A Mosfet is not. You would not want to do this but if you connected one lead of the coil to one of the contacts you would have something approaching the lack of isolation of the Mosfet.
- A relay contacts have no polarity consideration, a Mosfet does.
This means you cannot indiscriminately put a Mosfet where you could have added a relay contact. You must worry about the lack of isolation, polarity and the voltages required to be able to control the Mosfet from your arduino.
Those rfp30n06le mosfets are fine, as said above you will have to bump down the voltage, shown in the diagram, i posted prior where i used some resistors and the reflecting diode
Well, I appreciate the help. I guess I will stick with relays with my current configuration. I may be getting in over my head using anything else. Since the day I got my relay module I had problems with one relay randomly clicking on and off whenever I set it high. But, when I got the module, I was still figuring out the arduino and I just chalked it up to interference and now I'm guessing that is not the case. I resoldered the components that control the relay in question thinking it was a weak or cold solder joint because surface mount components appear to barely be soldered in the first place. That did not help. Am I to assume the relay is bad and order a new one?
I get sticky relays often but not ones that click on and off rapidly, i can only assume you have a micro break in the connection to that relay, else make sure you are not using a pin that is doing something else or is affected by a library or in pwm mode. to make it simple swap that clicking relay digital pin with one that is WAI and see if it stops if it does its the digital pin or code effecting it else if it still does it try a different cable else look on the pcb tracks for a break or lose connection
An inadequate power supply on the coil will cause it to rapidly drop out as the voltage sags and then re-energize when the voltage comes back up. What are you using for the coil voltage supply?
Since it's in my truck I have it connected to a phone charger that plugs into the 12v socket. It actually has 2 usb slots in it. One at 1 amp and the other at 2 amps. The 1 amp usb slot is powering the arduino and the 2 amp powers the relay module separately. I have tried many different digital pins and I have inspected the board very closely and found no breaks in the pcb tracks and nothing out of the ordinary. It looks perfect. I've just never seen a relay act like that.