Hello again!
I am thinking of creating a soundproof box for my projector to heavily reduce fan noise (subject to some prototyping). I want to exhaust heat into the loftspace using 120mm fans and intake air either via loft or from lounge where projector resides using silent 120mm fan.
I am thinking of using an arduino to provide some feedback on fan speed (so I know if any of them have died) and also the temperature of the enclosure.
My idea is to have an arduino which is powered by a 12v transformer (via the loft) which will power 3 fans (2 for exhaust, 1 for intake) and also take speed readings on 3 pin configuration of each fan and also a temprature reading.
I'd like to have a display with a reference to the speed of each fan (so I know each fan is working) and possibly display either a direct temperature reading or a 'high temprature' indicator light. Display could be LEDs with specific meanings or an actual graphical/LCD display on a discreet side of the enclosure.
What would be the most appropriate arduino board to achieve this? Is there any feasibility issues that I may have overlooked?
My biggest concern is having fan failures and overheading issues/fire hazards hence the arduino for feedback - I could just power the fans directly from supply otherwise.
P.S I recently posted about inverting HDMI signals so this is my second attempt at addressing the issue!
Any Arduino can handle a couple of temperature sensors and 3 fans, with many pins left over for I/O. You will need external circuitry to control the fans, which depends on the fan details.
Where is the intake air coming from? The loft may be significantly hotter than the room on hot days.
Any small reduction in intake air temperature will make a huge difference to the life of the projector lamp. I had a projector that popped lamps every 6 months and putting a Peltier cooler on the inlet increased that to 2 years. The actual drop in air temperature from the Peltier was quite small: less than 4C if I remember correctly.
MorganS:
Where is the intake air coming from? The loft may be significantly hotter than the room on hot days.
Cybercitymix:
I want to exhaust heat into the loftspace using 120mm fans and intake air either via loft or from lounge where projector resides using silent 120mm fan.
Might be less complex/ bulky to have one or more "silent" fans directing (cooler) air in the room toward the intake of the projector.
Cybercitymix:
P.S I recently posted about inverting HDMI signals so this is my second attempt at addressing the issue!
During testing how to cool 2 pieces of inverters, delivering 20kW each, it was discouvered that sucking air out from the rather closed compartment gave the best result. That construction worked, and still works, well all around the globe. Aerodynamics is never easy, never obvious, and depending on how the air flows around the hot lamp tests would be good to perform.
Peltier coolers are a nice idea but where does the heat from them go and the heat from the power supply powering them. There are switches called sail switches, they will detect the passage of air and can have there sensitivity adjusted. I have used them in many applications long before microcontrollers. For the fan solution I would consider looking at the static pressure diagrams for the fans, some push much better then they suck, which will dramatically effect air flow. Best having them run in parallel. Next determine the maximum temperature allowed in the box Then calculate the wattage of heat generated. Next determine the worse case ambient temperature. Remember you will have to provide more air then the projector fans pass. Using thermal dynamic simulation you can calculate the amount of air flow you need and size the fans appropriately. Any increase in temperature in the box reduces the life of everything, the converse is also true. There are switches called sail switches, they will detect the passage of air and can have there sensitivity adjusted. This response is to help you get started in solving your problem, not solve it for you.
Good Luck & Have Fun!
Gil
Not sure of the value of the fan running detectors. If during normal conditions, there is no high temperature condition in the area, then if you do get a high temperature condition, you will probably still have to go see what the problem is weather the fans are running or not.
Peltier coolers look very interesting but not sure they are right for this project as it makes it more complex and adds additional heat/energy concerns (but thank you for the introduction!).
I would prefer to take air from the loft so there are no openings into the lounge but am very conerned about the hotter air during summer (as mentioned) and also higher dust/dirt particle count. I will do some prototyping out of MDF and carpet underlay to try and find a configuration that allows for an intake opening in the lounge that doesn't carry internal noise too much.
Fan question: if I had two (or more) static flow fans pulling out air into the loft over the projector exhaust would an intake fan be necessary? (assuming the exhaust fans displaced more air than the projector puts out)? Another thought is of the danger these fans would pull air around the projector rather than through it and inadvertantly impact projector cooling.
The ultimate safety would be a reliable temperature sensor that cuts off the current to the lamp if a desired maximum temperature is exceeded. That will save Your equipment regardless of the reason for the high temperature, fans stopped of too high temperature of the cooling air.