The model is currently on sale at Pololu:
https://www.pololu.com/product/2312 (https://www.pololu.com/product/2312)
Its a 12" stroke model without feedback. The project I have in mind would be the simple lifting of a tombstone with a plywood backing- maybe 15 pounds. I'd like to have it where its just running on its on in the yard with no trigger mechanism, just lifting on its own every couple of minutes. If the EZ-3 Micro will not work for this, how about a Prop-1?
Thanks for your help as always!
Rick
You can use a Prop-1 and a couple relay, or you can use an h-bridge circuit. Remember, a linear actuator has a motor that has run run forward and reverse to operate; it's not like a pneumatic cylinder that will drop when air is taken away. The feedback circuits will let you know that it is fully extended or retracted.
From the Pololu web page:
To test-drive the actuator, simply connect a power source of up to 12 V to the motor leads. Reversing the applied voltage will reverse the direction of motion. A motor controller or motor driver is required for electronic speed and direction control.
(Underline mine)
Should I get one with feedback instead? I thought if I could just get one without feedback, the prop tombstone would go up, and then come back down later. What do you recommend or would be easier as far as putting in the relay or buying an H bridge? Pololu has one of those as well.
https://www.pololu.com/product/1212 (https://www.pololu.com/product/1212)
I assume I will need a separate regulated 12v supply for just the linear actuator.
Thanks again! Happy Thanksgiving!
If you want the actuator to fully extend, you don't need the potentiometer feedback. The standard actuator has limit switches that cut the power. The Prop-1 with two SPDT relays is all you need. Also, a single 12V power supply with enough amperage to operate the actuator will take care of everything.
If the full running speed of the actuator is not a problem, you can in fact use two relays as Jack points out. You'll need a DPDT to control direction, and a SPST or SPDT to control power. An H-Bridge is a solid state version of how the DPDT relay is connected.
(http://www.efx-tek.com/files/motor_reverse.jpg)
It just occurred to me that you could do this with an RC-2 -- apparently, it did some time ago as well because I found this drawing on my system:
(http://www.efx-tek.com/files/rc-2_motor_reverse.png)
In this case, when the outputs (P0 and P1) are at the same level, the motor will be in a braking condition (the circuit above allows it to coast). With the RC-2 circuit, only one output is high to make the motor move; the pin that is high controls direction.