8/15/03 I'm back....STILL haven't gotten my tank yet...grrrr. Supposed to pick it up next weekend...we'll see.
I was reading on the reef central forum, and someone had posted how they built an aquarium feeding timer because they were tired of forgetting to plug their pump and powerhead back in after feeding time. Well, my ultimate plan is for SPS corals, and they are filter feeders, I thought WOW what a great idea. The person did not post a schematic, only a couple of pictures of the finished device. Well, I didn't have a tank, so I was bored. I started DIY project #2... A solid state feeding timer based on the LM555 IC, and a heavy duty PC board mount relay.
The device posted in the reef central forums gave me a start of an idea for the form factor, I knew I wanted to be able to mount this in my cabinet and have a remote
switch on my canopy for the feedings. Basically what this does is when you press the switch it turns of the pump for a set amount of time by cutting the AC power to the pump.
**** DISCLAIMER: I TAKE ABSOLUTELY NO RESPONSIBILITY FOR THE SUITABILITY OF THIS CIRCUIT FOR ANY USE. I also take no responsibility
if you electrocute yourself, your wife (husband), or your fish, or burn your neighborhood down, or make another 2003 Blackout in your section of the country!
If you choose to proceed, you are doing so at your OWN risk!****
That being said, mine works just fine for me. Here is what I came up with:
I won't go into much detail about the circuit design...A few notes here. It is based on a nearly universal IC timer called a 555. I used a circuit design called
a monostable oscillator circuit. The important thing for any DIYers trying this, the values of R1 and C1 CONTROL THE AMOUNT OF TIME.
Here is a good page to estimate how many seconds different values of R1 and C1 will give you:Value Calculator.
I ended up using a vale of 2200uF for C1 and a value of 1Mohm for R1. This calculates out to 45 minutes, but due to the variances of any components, the ACTUAL
time delay this gives is 53 minutes. Here is a board layout:
The final size of my project was 4.5"L x 3.5"W x 2" H including my spiffy DIY acrylic enclosure (I now love acrylic)