555 based Reset Generator
This circuit is a part of an older one which has been removed. I have taken a snapshot of a part to explain.The top circuit is a 555 monostable, The push-switch is to trigger and generate a reset pulse for uC. The diode is for OR' ing later. The High will go thru the diode but the Low of 555 cannot drink any current as diode blocks.
555 and 556 Timer Circuits
Discover Circuits - One Shot / Monostable Circuits
The 555 Timer
The bottom part of the Circuit is the CD4093 Schmitt nand based flipflop. This is my favorite because of Elektor Electronics
circuits. What is the Schmitt then ?, It is better to visit the links below to learn. It can make a sine or triangle or any shape waveform to square. It can help square a very messy waveform.
Schmitt Trigger Applications,
Schmitt Trigger 1,
Schmitt Trigger 2,
Schmitt trigger - Wikipedia, German Schmitt.
Two nand gates are connected to form a flip-flop toggle switch. When 555 gives out a pulse, the pulse is delayed by a R-C which results in a ramp, the third nand-Schmitt gives out delayed low trigger to toggle nand-flipflop-switch. The Nand-toggle-switch is rest at any time with the lower pushbutton. The fourth nand output gate is not really required. But the 4093 is quad nand, so unused nand inputs should not float , pull-up or pull-down. So it has just been added in circuit so that he can fit some role, or else he will be bored.
Now you can figure out how such blocks can be used like Lego blocks in your own amazing designs.
