Hello Group.
I've been working on a project to supplement a marine refer using cold outside air (a winter scenario only) in lieu of the 6 amps required to run the refrigeration compressor. So far I've had help getting my Picaxe 08m to take to temp. readings (both outside and in the refer) from a couple of DS18B20's and then to turn on a small fan which would pump the outside air into the refer. I've got that part working pretty well.
But one problem I still need to overcome is to build a small duct "valve" which will only open (90 degrees) when the fan turns on (to avoid the problem of a warm breeze accidentally blowing into the refer when the outside air is too warm).
I've been looking at various motors/actuators with the goal of rotating a shaft 90 degrees to open the valve and then back 90 degrees to close the valve. I don't want the motor to draw amperage after the valve has been rotated in either position.
I also may be pushing things with a single 08m chip but I can deal with that later.
But given this, has anyone thought of a way to power a small motor/actuator on-off to accomplish this feat? Solenoids seem to draw significant amperage when "on" and few are suited for continuous duty. Servos seem to need PWM for all positions, unless I'm mistaken and can automatically return to a preset position when powered down.
To complicate things, I'd love to do this with only one output pin on the Picaxe. Am I crazy?
Thanks for any ideas or help.
Gene Darby
I've been working on a project to supplement a marine refer using cold outside air (a winter scenario only) in lieu of the 6 amps required to run the refrigeration compressor. So far I've had help getting my Picaxe 08m to take to temp. readings (both outside and in the refer) from a couple of DS18B20's and then to turn on a small fan which would pump the outside air into the refer. I've got that part working pretty well.
But one problem I still need to overcome is to build a small duct "valve" which will only open (90 degrees) when the fan turns on (to avoid the problem of a warm breeze accidentally blowing into the refer when the outside air is too warm).
I've been looking at various motors/actuators with the goal of rotating a shaft 90 degrees to open the valve and then back 90 degrees to close the valve. I don't want the motor to draw amperage after the valve has been rotated in either position.
I also may be pushing things with a single 08m chip but I can deal with that later.
But given this, has anyone thought of a way to power a small motor/actuator on-off to accomplish this feat? Solenoids seem to draw significant amperage when "on" and few are suited for continuous duty. Servos seem to need PWM for all positions, unless I'm mistaken and can automatically return to a preset position when powered down.
To complicate things, I'd love to do this with only one output pin on the Picaxe. Am I crazy?
Thanks for any ideas or help.
Gene Darby