But the amount of work programing them is much greater, there is a significant learning curve (which I haven't climbed). Then there is the issue of programming them, a one time cost in hardware to interface with a µC, which is not included in your estimate.Hi Cfoek
You could also have done this with a small 8 pin microcontroller and a very few components. Microcontrollers have become a very useful tool for the hobbyist. And the cost of a small microcontroller is almost the same as 555 circuit.
That is the contact rating, I need the coil rating. How much current and voltage does it take to drive the coil? While I'm asking, what are you going to drive, a motor? What is its rating?the relay is dc 28v 10a
That sounds fine for powering the 555. They can only take 15V max. Don't exceed it.for powering i use transformer 220V - 12V 500 ma then brige dioda 2A then 1000uf 25V electrolyte then 7812 and the last one ceramic 0.1uf, what did you think ?
If you look at the schematic I included the formula for just such a question.if i want to change the delay from 3 second to 5 second or more what resistor and capacitor need to be change ?
thanks
A microcontroller is a piece of silicon just like some 555 circuits. It is just a tool. In my toolbox it is a tool I use then I find it convenient perhaps more frequent than other tools. Other may have a toolbox with different tool(s) they like to use.so it will be a waste to use a microcontroller just be a door bell protector hahahah