BS2, driving a pump/AC motor, latch output?
Inerlogic
Posts: 4
ok, after a bunch of searching around on the forums i didn't see anything that i figured could help me, so here goes...
i'm looking to convert a system at the lab i work at from analog electronics
(which have ceased to work, and it's inventor has passed away and left no schematics)
to being controlled by a BS2
the device i am looking to control is for bleach regeneration in a photo processing lab,
here's what i need to do:
high level float sensor trips indicating the tank is full
a buzzer in the darkroom is triggered and a lightbulb outside the darkroom is lit (40watt AC current)
thus alerted the ever vigilant darkroom tech adds the appropriate ammount of regenerator to the tank and pushes a button
this button press will silence the buzzer, turn off the lightbulb and will start a 120V AC motor in the tank which mixes the solution
for 15 minutes, i'd like this 15 minutes to be adjustable which is why i like a microcontroller for this project.
anyway, after the set mixing time, the mixer should shut off, and a peristaltic pump is activated which pumps the
mixed solution back up to the source tank until the liquid level gets low enough to deactivate the low level float sensor.
i've been experimenting with the BS2 homework board, but i've ordered 2 of the BS2 OEM kits for use when i finally implement
this solution. i do not have the specs on the AC mixer's motor or the AC peristaltic pump, the unit as it stands now has a 6amp fuse
on the AC line, so i figure if i use relays rated for at least 10Amps i'll be good to go....
i've included ALL the details i could think of looking for any expert suggestions from the members here [noparse]:)[/noparse]
the specific issue i was wondering about is the 18ms drop-out every 2.3 seconds with the BS2
if i drive a mechanical relay (with a transistor) will the relay "chatter?" every 2.3 seconds?
i don't want to deal with a lot of heat as i'd like to seal the controller board and electronics from the environment (photochemistry is quite corrosive)
so i wasn't considering solid state stuff... would a cap across the relay's coil leads dampen the 18ms drop-out?
should i look into a D-latch?
are there any gotchas i haven't thought of?
Thank you for your time [noparse]:)[/noparse]
i'm looking to convert a system at the lab i work at from analog electronics
(which have ceased to work, and it's inventor has passed away and left no schematics)
to being controlled by a BS2
the device i am looking to control is for bleach regeneration in a photo processing lab,
here's what i need to do:
high level float sensor trips indicating the tank is full
a buzzer in the darkroom is triggered and a lightbulb outside the darkroom is lit (40watt AC current)
thus alerted the ever vigilant darkroom tech adds the appropriate ammount of regenerator to the tank and pushes a button
this button press will silence the buzzer, turn off the lightbulb and will start a 120V AC motor in the tank which mixes the solution
for 15 minutes, i'd like this 15 minutes to be adjustable which is why i like a microcontroller for this project.
anyway, after the set mixing time, the mixer should shut off, and a peristaltic pump is activated which pumps the
mixed solution back up to the source tank until the liquid level gets low enough to deactivate the low level float sensor.
i've been experimenting with the BS2 homework board, but i've ordered 2 of the BS2 OEM kits for use when i finally implement
this solution. i do not have the specs on the AC mixer's motor or the AC peristaltic pump, the unit as it stands now has a 6amp fuse
on the AC line, so i figure if i use relays rated for at least 10Amps i'll be good to go....
i've included ALL the details i could think of looking for any expert suggestions from the members here [noparse]:)[/noparse]
the specific issue i was wondering about is the 18ms drop-out every 2.3 seconds with the BS2
if i drive a mechanical relay (with a transistor) will the relay "chatter?" every 2.3 seconds?
i don't want to deal with a lot of heat as i'd like to seal the controller board and electronics from the environment (photochemistry is quite corrosive)
so i wasn't considering solid state stuff... would a cap across the relay's coil leads dampen the 18ms drop-out?
should i look into a D-latch?
are there any gotchas i haven't thought of?
Thank you for your time [noparse]:)[/noparse]
Comments
·· The "drop-out" you refer to happens either when you use the SLEEP command or the program ends and is a result of the internal watchdog timer.· If your program doesn't end this won't happen.· You can end it with STOP which will also prevent this.· Depending on how the circuit is driven you could also use a pull-up/pull-down resistor to keep the line pulled toward the desired signal.· This really depends on many factors though.
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Chris Savage
Parallax Tech Support
csavage@parallax.com
oh, and i don't actually want the program to end, once it steps through the process, i want it to go back and wait for the high level senor to go high again...
Depending on how the circuit is driven you could also use a pull-up/pull-down resistor to keep the line pulled toward the desired signal. This really depends on many factors though.
well, i was going to have an output pin from the stamp tied to the base of a transistor which would drive a relay which would in turn (no pun intended, honest) drive the motor (and seperate ones to drive the lightbulb and pump)
or use a MOSFET to drive the relay which drives the motor....
i'm just looking for some expertise from those who've done this type of thing before so i don't have to be a guinea pig,
why re-invent the wheel ya know? [noparse]:)[/noparse]
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Chris Savage
Parallax Tech Support
csavage@parallax.com
i set a BS2 pin high to direct drive an LED and then put the stamp to sleep..
flicker-flicker
tie a pin to the gate of an IRF-510, use that to drive the LED (a subsititute for my load) and the gate retains enough charge
to keep the LED lit steady...
haven't hooked up the scope to see what's really going on, but i think this may just do it...
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Chris Savage
Parallax Tech Support
csavage@parallax.com
i'll let you know [noparse];)[/noparse]