Fish Tank Lights and Temperature Detector

When the tank is cleaned the fish are removed and placed in a small amount of the tank water. The problem is that fish don’t like rapid temperature fluctuations. I guess a simple in tank or stick on thermometer would have done the trick but what is the fun in that? If the unit just did temperature monitoring it would have been such a waste of processor capability, so I thought adding colored lighting would be a great addition. Uses 16 high power LED’s, 4 red, 4 green, 4 white and 4 blue. The tube that the LEDs are mounted in is a section of 3/4 inch PVC conduit. LCD Display to display the mode the unit is in and show the temperature. Liquid sealed temperature to read the water temperature. One button to change between modes. Photocell to turn off the lights when there is adequate room light. This is wired and calibrated but this function has been remove to allow the lights to remain on all the time.
Fish Tank Lights and Temperature Detector - schematic

Fish Tank Lights and Temperature Detector - img1

1) Prep the Light Tube: Cut a section of the PVC Conduit to the desired length, a hacksaw makes quick work of this type of pipe. Cut the pipe in half length wise, drill 16 evenly spaced holes in one of the halves. 2) Mount and Wire LED’s: Hot glue an LED into each of the holes alternating the colors. After the glue is dry, wire up the like colored LED’s in series with an adequate current limiting resistor. 3) Wire the Temperature Sensor: Connect the 3 terminal temperature sensor up to the cable that will be used. Hot glue and heat shrink will make for a water tight seal. The temperature sensor being used is made by Dallas Semiconductor, it is model DS1822. 4) Assemble the Light Tube: Connect the LED power connections to the cable that will be used. Lay the temperature sensor cable through the light tube leaving enough sticking out the side to dip into the water from the height the unit will be mounted. Wrap the entire light tube in black electrical tape, making sure the LED’s are not covered. 5) Construct Circuit Board: Use some perf board to create the circuit board, there is schematic below to aid in the construction of the circuit. Wire it up to a 2 line LCD panel. 6) Connect External Cables to Control Unit: To power this unit I used an 18VDC wall wart type power supply. A 5V regulator was used to provide stable and clean power the PIC. Hook up the temperature sensor wires LED power cable to the perf...

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