R-2R Digital to Analog Converter with LM358
Use this circuit as a low cost alternative to a commercial DAC. It is important that the latch be a CMOS device, so that the outputs drive to Vcc when they are high. (TTL devices only drive to 2.4 volts or so). I have shown the ‘573 latch rather than the ‘373 which can also be used. The ‘573 has the advantage of sequential pin-outs for the Q0 - Q7 pins, making it easier to connect in most circuit layouts.The LM358 OpAmp is a good choice for this circuit for two reasons: 1) It can be powered from the 5V supply. 2) Its output can go to 0V without a negative power supply. Note that the LM358 is a dual OpAmp, so the other half is unused in this circuit. Link
Other Link
Stepping Motor Driver using XNOR gate
Standard Touch Switch by IC Gate 4011
Bounceless Switch by IC 555
Digital Step-Km Counter with IC 4026,4024
