cost is the criterion for me as I need at least 10 tracking assemblies for what I want to do during the summer which is power providing at festivals ... sometimes a big combined array for a stage sometimes small separate arrays for cafe, stall or poets corner etc. so at least 10 arrays but at on the positive side its only single axis control I need as I'm setting up at new festie each week or so. Following your development with interest mark
You need to check the current consumption of your linear actuator. I'm still convinced that your circuit design is poor and that it could be what causes the heat itself. In my opinion, if the circuit is made properly, then the little 12V motor and actuator should not cause any kind of heat generation. Please post a more organized schematic of your circuit.
I'm going to "poke" at your schematic a little, I think that U2 C and D are a redundancy. I don't understand why you have the 2 2.2k resistors. Also I think that you should get rid of the voltage divider on U2 A and B. Why not use a standard H-Bridge, why do you have to use the MOSFET's in that particular configuration?
I've included an attachment of a circuit I made several years ago, it's a simple circuit (yes this circuit works) and it can track fairly accurately. The motor should be as low of a power as possible.
Thank you for explaining that (I've been asking about that for a while now). On another note, I noticed that you didn't include limit switches... why? Since you are using FETs then it should be easy to put them into the design. Instead of turning the motor off at night, why don't you use U2 C/D to make the circuit think that the sun was in the easern sky?
We were building this circuit a step at a time and limit switches were next, one each to be placed at the bottom of the 2.2k resistors. The limit switch on the Eastern extreme of the motor excursion would probably make the darkness comparator on the East photodiode unnecessary.
But Dragon Tamer entered in message #116 saying that we scrap it and start over.
Your call.
I had an idea for the return east function, but seeing as how you have that taken care of, I'm going to stay out of it. I do however have another idea, since Q4 is getting hot, why not make a circuit that will cool it? Really simple to make and can be part of a different circuit. I'm under the assumtion that this is going to be outside (if not I'm going to have to drive all the way down to Tennessee just to smack some sense into you). You'll obviously need to make a housing for your circuit. The fan can just sit at the bottom of the housing to cool (so rain does not get in). I can have the circuit ready for you today if you want.
Also, If you still want to make the "North" and "South" functions, then my idea for the return to east will be really simple (and good).
Does Q4 get hot/warm when the system is idling or just when you go East a lot?
I was going to say that you could add a second comparator for the up and down rotation (I'll call it U1), and just make U2 C/D work with U1 C/D then just put a limit switch (PBNC) on the V+ pin of the 339.
I have made the fan for the circuit if your still interested in it. It doesn't even interact with the solar tracker circuit, it does it's own specific duties (with relative efficiency). You can even add a simple solar activated circuit to turn the fan and the IC's off at night so they do not waste power. The circuit can be arranged for several different configurations, but this is the best because it will cut the power to the fan if the fan is not needed. It will differentiate between the temp of the heat sink on Q4 and the ambient temperature. R2 is to adjust the speed of the fan. You can use any op-amp with this circuit, but it must be an op-amp. R12 can be replaced with a higher resistance value, but the gain will not be as high as it is currently set to (a gain of 11). If you have any questions just ask.
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