![]() However, only one LED will be switched “ON” at any one time depending whether the output state is “HIGH” or “LOW”. The ability of the ripple counter to both sink and source its output load current means that both LED’s can be connected to one output terminal increasing the number of LED’s we can use within our simple LED flasher circuit. This means that the current will “Source” (supply) or flow out of the 4040 counters output terminal and the LED will be “ON” when the output is “HIGH”. The second circuit above shows that the LED is connected between the output, Q8 and ground ( 0v ). This means that the current will “Sink” (absorb) or flow into the 4040 counters output terminal and the LED will be “ON” when the output is “LOW”. In the first circuit above, the LED is connected between the positive supply rail ( +Vcc ) and the output, in this case Q8. The ability of the 4040 counter to both “Sink” (absorb) and “Source” (supply) current means that the LEDs can be connected between the output terminal of the counter and the supply to sink the load current or between the output terminal and ground to source the load current. The counters outputs Q1 to Q12 have the ability to either “Sink” or “Source” a load current of up to a maximum of about 15mA, which is sufficient to directly drive the LEDs. 4040 Ripple Counter Timing Diagramīy connecting the LED’s to different outputs they will flash one at a time but at different rates to each other (each output half the frequency of the previous one) and will not be all “ON” or all “OFF” together making it ideal for our simple LED flasher circuit.īy using divide-by-2 frequency divider/counters, with multiple LED’s connected to their outputs, it is possible to produce a twinkling star or flashing lights effect or any LED flashing lights display of your choice depending upon which ripple output you connect the LEDs to and how you physically arrange them. The outputs of the 4040 switch between a logic “1” or “HIGH” and a logic “0” or “LOW” on each count so it can produce a moving sequence, chaser or random effect, making the 4040 ideal as a simple LED flasher or lighting display for a lights project.Īs the 4040 is a 12-bit ripple counter, each one of the twelve outputs will toggle HIGH or LOW in a binary sequence from 0 to 4096 (2 12), and this is shown in the following timing diagram. These twelve outputs switch sequentially on the arrival of each negative-going edge of the clock pulse producing a binary output sequence as shown in the timing diagram. ![]() The CD4040B is a fast switching 12-bit binary ripple counter complete with twelve fully decoded outputs (making a total of 12 individual LED sequence’s). So for example, output Q6 is 2 6 = 64 ( 1/ 64 of the clock frequency) and Q12 is 2 12 = 4096 ( 1/ 4096 of the clock frequency) and so on.Īs we have seen, there are many binary counters available that can flash any number of lights periodically, randomly or sequentially but one very versatile IC that the hobbyist or student can use to produce a simple LED flasher for use in a variety of different lighting displays is the CMOS CD4040B 12-bit Binary Counter. Then their output count, ( Qn) would be defined as the “N-th” stage of the counter. Ripple counters are constructed from a number of divide-by-2, T-type flip-flops cascaded together to form a single divide-by-N frequency divider, where N is equal to the counters bit-count. The result is a ripple effect as each stage changes in sequence and we can put this to good effect as a simple LED flasher circuit. The toggle or “T-type” flip-flop is the basic building block of all counters with asynchronous counters are commonly referred to as “ripple counters” because the input clock pulse appears to “ripple” through the counter as the clock input for one stage is generated from the output of the previous stage. Usually the toggling occurs on the negative edge of the clock pulse. ![]() These types of counters are asynchronous in nature because not all the flip-flops change or “toggle” together with the application of an external clock pulse. Ripple counters as we discussed in the Counters tutorial, are basically toggle flip-flops that can be used as frequency dividers to divide the reference clock input by a set amount to give a new, lower frequency and which we can use as part of our simple LED flasher design. The electronics student or hobbyist’s always likes to make various circuits for their home or school and especially ones that flashes a few lights, and there are many circuits and kits on the market that can flash any number of LED’s or lights periodically, randomly or sequentially but one very versatile IC that can be used to produce a simple LED flasher circuit is called a binary ripple counter.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |