Hello everyone, I would like to ask a couple of questions bout rectifiers (which i hate) and how it heats up my Atmega128 (which i love)
My story starts with #6, if you dont know what #6 is I do suggest you check out their site over [http://blunt.media.mit.edu:8080/6/], but it is basically an MIT group that did a re programmable and easily usable ATMega32 broad. They used a rectifier, and two capacitors a 47uf capacitor and a 4.7uf capacitor (assume the u stands for micro.)
Now after I designed the first board which contained an ATMega128 with a different purpose then the #6, to light green and red based on certain inputs all worked fine but I found the ATMega128 to be heating up, I found out that the voltage coming out from my 5V regulator (tried several regulators) was more than 5V, tracing the problem i ended up removing the Rectifier since I already just input a DC Voltage to my board, so why use the Rectifier right?
I ended up making four board designs all the same but without the Rectifier and came up with those results:
Board#1 Worked onspot, a bit fishy sometimes bas stable in the end.
Board#2 Didn't work so as I was debugging it I placed an AmpMeter between the Regulator and the 5V line of my board and it suddenly worked! I removed the AmpMeter and reconnected the lines to themselves and the board wouldn't work again. I was baffled, I know the AmpMeter has some resistance but it should be negligible resistance no? and this resistance shouldn't be what decides if the board functions or not.
Needless to say I got the same results on Boards2,3,4. So the rectifier came back into the equation, all though am not sure why, but when I place it back into the circuit it works just fine again (expect it overheats) I don't understand why the rectifier is the determining factor even though I am not using any AC input. I tired to lower the capacitor values as I read online the bigger the capacitor the smaller the ripples but the higher the current, still to no avail.
My Circuit takes around 250mA max while this rectifier can hold up to 1A, the only problem as I see it is that it is letting out more than 5V on the Regulator pin which most probably the reason, as I tired with a 6V input which produced a 4.32V output at the regulator, and then it was fine, but I need a 12V input.
I attached the graph of how the Regulator/Rectifier are connected, the #6Board (Eagle Cad) if anyone needs it for any reason and the Rectifier datasheet mine is 107[/url]
If you could take out a minute or two to help me I'd appreciate it, I am still pondering why the board doesn't work without a rectifier even though I am not using any AC components (Capacitors, MAX232, RS232, ATMega128) and in addition I built the #6 board myself and it doesn't heat up nor anything which I find to be very weird. Is there a way to work it without having a rectifier? or is there a way to keep my regulator output at bay with 5V? Thanks in advance