Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

BCD counter

Status
Not open for further replies.

G_G1

New Member
Hi there, new to all this electronics stuff.
Could anyone explain to me how a BCD counter actually works and what role TTL plays?

Should probably add that the counting in question is perfromed by 2 74LS90 ICs
 
Last edited:
First of all TTL means Transistor Transistor Logic and it just indicates the technology which is being used in the IC. Secondly 74LS90 is a Decade counter which means that i can count from 0 to 9(looks like BCD?).

**broken link removed**

The above link gives the timing daigram of a decade counter.The last output bit(Qd) of the first 7490 is given to the clock i/p(CKA) of the second. When the 1st 7490 goes from 9 to 0, the next 7490 increases by 1 and every time this happens the second 7490 increaes by 1.Here is a link(there is some thing wrong with my windows otherwise would have edited that for you)

HowStuffWorks "How Digital Clocks Work"

It shows how to connect the 7490 as Decade/BCD/Divde by 10 counter.For two such counters gives the 11 pin output of the 1st 7490 to the 14 pin of the next.
 
Last edited:
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top