555 based Reset Generator - del50008
You must have read all the circuits and
explanation on the other pages at delabs to
understand this, as i cannot repeat the same thing as
i have done it more than once already.
8051 Single Board Computer - This is just like
the SBC i did decades before using 80C31, before the
The 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 multivibrator like power oscillator
The bottom part of the Circuit is the CD4093
Schmitt nand based flipflop. This is my favorite
because of studying designs in
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.
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
Lego blocks in
your own amazing designs
Trigger Voltage in 555
Trigger VoltageThe pulse/level at pin 2 should
drop below 1/3 Vcc before the timer triggers.