I'm wondering if someone can be of help! I developed a program to count teeth of a gear and stop a specific count. The program is working as needed but I am having trouble actuating a 24v coil omron relay. Using a boost converter it will show the 24v on the voltage out but once under load drops to 9 volts, same with a bigger boost converter. I tread also wiring directly into the start switch of the motor but would'nt interrupt the signal using a pwm mosfet switch. Anyone have any experience getting the 24v coil relays to work with the 5v pwm out signal?
A boost converter isn't going to work directly from an output pin because it can't put out enough current. You can't boost energy... You're going to need about 5X the current from the 5V source as the relay coil is using, and that's in addition to whatever current is needed just to keep the boost converter running.
But, you should be able to boost the 5V from the power supply (assuming you have enough current capability) and then you can use a MOSFET driver to switch the 24V relay coil.
PWM doesn't work with regular electro-mechanical relays. They are too slow and you wouldn't want them to switch rapidly anyway.
Omron makes thousands of different relays, does yours have a part number?
I am going to assume you are using an external power supply. DVDoug schematic is great and will work without a problem. You need to connect the boost converter to the 5V power supply not the Arduino 5V pin. Connect the ground - output of the boost converter to the 5V ground the +24 as show in the schematic.
This schematic is different then the ones you generally find on the internet, but it is the correct one, most of the others are wrong where they connect R2 to the gate pin. It needs to be connected to the Arduino port pin. Connecting to the gate forms a voltage divider. R2s main purpose is to be sure the MOSFET is off from reset until you set its output.
thank you for the response, i'm still on a learning curve with some of the wiring and schematics aspect. I was trying to use the 5v power from the arduino to boost an supply to a 24v coil relay. Would it be possible to pull power from the arduino 5v pin itself and boost there. I am trying to add this to an older machine where there isn't a direct access for external power.
thank you for your response! i am still earning the wiring and schematics aspects after coding. In this diagram am i to connect a 10k resistor between the positive out and ground of the arduino? And that is a diode in between the Mosfet and relay?
Yes. For example if you use pin 10 as output, the 10K goes between pin 10 and GND and the 220 connects between pin 10 and the MOSFET gate.
And that is a diode in between the Mosfet and relay?
The diode connects across the relay coil with the cathode (end with the band) connected to the side that connects to the +24V
Thank You, that makes more sense knowing the resistors don't carry a voltage. On the output pin side m i correct that is connecting on the same terminal with the split ground wire depicted?
Does this make it clear
N
Your USB is rated at maybe 500mA max depends on type ,etc. Boosting 5V to 24V will require about 5X the coil current of the relay coil so the current required for a 100mA coil @ 24V is now 500mA at 5V. The odds of that working is slim. What is the relay switching? What current and amps?
dayton relay 2A584M 300v @10a max with a 24v coil (omron MY4)
There are a lot of them, that is a family name. How much coil current does your relay require and does it have an indicator light.
it requires 24v and no indicator light
thank you for taking the time to make this drawing. the visuals helped a lot with the build. my only question is this possible without an external 24v power supply?
No.
If the coil requires 24V then you need a 24V power supply capable of providing the required coil current.
thank you this is very helpful. one last question, would I also need a -24 on the relay to actuate the switch?
The 24V power supply will have two connections.
A positive connection, +24V and a minus connection, -24V sometimes called ground or common.
Is there a reason you are using a 24V coil relay?
i am wiring into an industrial machine and 24v was the lowest coil we have
i only ask from reading the diagram there are two +24 connections to the relay and wanted to make sure i was following correctly