Just some clarification here, if you could please....
I require a micro 4mm stroke solenoid to be used similar to a starter for an engine... the solenoid needs to push a small gear in/out to mate with a driver gear and run an assembly.
From my research I have gathered:
5v Solenoid requires: Resistor, Mosfet, Diode
12 Solenoid requires: Relay
I'm looking for most cost effective direction. But I'm not certain the pros/cons of using a 5v vs a 12v solenoid with my Arduino Mega 2560. If the Mega can power a solenoid with 5v, why would one use a 12v Solenoid? Do 5v and 12v solenoids have the same strength?
Your first consideration should be to find a solenoid that do what you want, whatever its voltage. If solenoids using both voltages are available then the next consideration will be how they are going to be powered. This depends on the voltage and current available.
It may, for instance, be sensible to power the whole project using 12V if that is what you have available or 5V if that is what you have. Either way the solenoid will not be driven or powered directly from the Arduino, hence the use of a relay or MOSFET. The relay or MOSFET decision will depend on factors such as current required to drive the solenoid, space available and relative cost
Unfortunately there is not a definitive answer to this and it may even come down to things like the MOSFET being a silent solution, not that it will matter in your case
Is there a lower cost solution between the two routes?
I'm presuming that because the RAMPS board is powered by 12v (for A4988 steppers) could the RAMPS board also power the 12v solenoid or even a 5v solenoid? Or does the solenoid still require its own power source direct from the PSU?
Would the 12v solenoid be more powerful than a 5v, is there a strength consideration? or is it based on the amps required?
Am I making any sense at all :o) .... still kindof new to all this.
Solenoids are like resistors. The also produce heat. How often will you power your solenoid and how long will it be powered each time? If either time is very long, you will need to be sure to cool the solenoid.
OK you have the stroke so next how much force is required?
The stroke is made from one end position to the other when energization occurs. The end position in one direction is therefore the start position for the other opposite direction. Solenoid force (F) is the useful force developed in the direction of the stroke after allowing for the fric- tional loss .
The force will be part of determining the solenoid coil current and how you drive the solenoid.
I did a project a few years ago using camera shutter solenoids. They were so weak, they would only work on camera shutters, So project changed to a small DC motor and a screw on the motor shaft to do the same work. Just took longer to operate.