ok i have been thinking about this for awhile now. i was wondering if anyone had any ideas on a DIY Thermostat Controller? i have an idea of how it would work but i am missing some details.
1. Maybe a refrigerator thermostat?
2. the probe, would a thin walled tube with the thermostat inside of it surrounded by some type of gel.?
Price:27.95
check this book west: i think ive promo'd this before to u guys!
i could prob suggest u look for the thermostats in the temp range that your looking for a start! but to put it simply i would consider cutting corners from things or items that have a lesser impact when things go wrong! u can cut corners on lights, tank stands ect & ect, but filtration & temp are not one of them! just my opinion west> if u still really want to go down that path i'll see what i can come up with, but its not wise considering whats at stake! i know your a techi, but unless u live at radio shack its not as easy as it looks to make it realiable!
I'm currently working on one. The aim is to have a microcontroller that does several things. One is temperature control, for which I need a thermostat of some sort.
I have opted to use a thermistor as the temperature sensing element. Hook that up to an Analogue to Digital Converter (ADC), a microcontroller, a bit of programming and soldering.... presto. At least thats the plan. So far I've got as far as putting together the thermistor and getting the microcontroller to work out the temperature. I still have a wee way to go.
In a style that is now becomming typical of the way I do things, I have gone for the extreme challenge. You dont need to go that far. You can set up a simple on/off thermostat using a voltage comparitor (a small electronic conponent) a few resistors, diodes and capacitors. There are plenty of free schematics available on the web.
The reason I am doing it the hard way is so that I can put in more complex control methods. On/off is ok, but it leads to cyclic variations in the control variable (in our case the temperature of the tank). in english... it goes up.... it comes down... over and over and over again. I want to see if I can keep it steady.
I do agree with the V man. Its usually easier and more reliable to buy reputable gear when it comes to filtration and temperature control.
I was hoping to do something more on the lines of the simple approach you mentioned. I would simply like to have a small fan or two kick on when things heat up. And I don't really want to spend $100 or more for such a simple control. Do you have any good links to reccommend? I'll post a few links if I find some promising ones.
These are exactly what I was talking about. They are all based on the same linear Operational Amplifier and should work fine for a small fan. Be sure to check the current rating on the fan to be sure you won't over-load your control circuit.
Were you wanting to control a mains powered fan? if so.... make sure you do your homework on working with mains power. Its dangerous, so dont rush in.
I was wondering if there might be anything like this simple heater controller for a fan? http://www.marinedepot.com/md_viewIt...roduct=HD03301 This could probably also be rigged up with a normally on relay, so that when the tank warmed enough the heater controller would turn off and the relay would close to turn on the fan. Seems silly but I haven't seen anything else to do the trick wihtout building a circuit or going overkill. Of course don't know exactly what the outputs and capacity of this device is...
Also a regular thermostat controlled fan could be used. I'm not sure about extending the therm on a lead to the tank, but just based on room temp you could experiment to get near the right point to have it kick on when needed?
typically they will draw a couple of hundred milli-amps. its usually written on the lable of the fan.
you could probably rig the bought thermostat unit up to operate a fan, but to be honest I think its really overkill. Those schematics you found will cost all of about $10 for parts, $20 for a soldering iron, and then a bit of time to solder it all together on a prototype board. If you stuff it up... you'll only have to replace a few cheap components, but if you cabbage the other thermostat, it'll be next to impossible to fix it cheaply, costing you the purchase price plus shipping.
Finally, if you use a thermistor as a sensing element, you can put it on a length of wire, waterproof it and dunk it into the tank. the low voltage means no rsk of frying fish, or yourself. Other thermostats that are not designed for wet environments would probably short out and die.
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