Dr. Sajid Muhaimin Choudhury

Thanks to all of you who tried my previous version of SI prog. One of my friends tried to implement it on his vero-board and it did not work. I gave him my previous one to test. Now there is a Curfew going on in Bangladesh so I could not get his one. So I tried to rebuild the previous circuit. It just did not work! I was flummoxed, and spent a whole day on it. Today I took a good look at the LancOs circuit and found out that they uses two separate reset lines, one through the collector of a BJT, and the another directly through a Zener Diode regulator. In my second circuit, I had omitted the sener regulator part, and had just used the BJT. Luckily I kept some extra space in my vero-board this time, and added the extra resistor and zener diode regulator. I was all out of 4.7K resistors and can’t go to the shop right now (because of the curfew), so I used 1.7Ks merely hoping that they would not fry my serial port. I disconnected the previous reset line (through the BJT) and connected the zener regulated version to the bread board, and it works!!! So I think for microcontrollers not having non inverted reset, this simpler circuit would be just fine.