T flip flops - Page 1
Forum section: electronics / beginners

author: christos
author_rank: Regular Contributor
timestamp: December 10, 2014, 06:03:06 pm
content: how can i make a circuit with T flip flops that will display with leds or with a Seven-segment display the number 3 7 8 2 over and over again ?

author: German_EE
author_rank: Super Contributor
timestamp: December 10, 2014, 10:06:30 pm
content: This is such an odd requirement that I think you should seriously consider using a microchip rather than discrete logic. A chip such as the PICAXE could be wired via resistors to the seven segments of the display and you would have a single chip solution.In any event I had to google 'T Flipflop' as it is something I had not encountered since my university days. They do not appear in any of the 74 series and you may have to use either 'D' or 'JK' devices.

author: c4757p
author_rank: Super Contributor
timestamp: December 10, 2014, 10:14:50 pm
content: Why?

author: Paul Price
author_rank: Super Contributor
timestamp: December 10, 2014, 10:17:55 pm
content: Maybe with J-K or J *K or even "D" FF's.What you really are trying to build is a state machine with a boring one-track mind.What this means using T FF's is that you need lotsa steering logic to order machine states to display your required sequence..this would be truly a Rube Goldberg solution.It is something so easily done with any one single micro controller chip, and it can be made by directly connecting the 7-seg LED segs to a single 8-bit port, and the design also requires only one resistor to limit CA or CC current.You could do the same thing with a CMOS 4017 and a 555 timer or 74LS00 for a bounceless clock and all so many segment select diodes for each number displayed.Of course, you can use lotsa RTL diode steering circuits to accomplish the same with multiple custom arrays of T FF's if you wanna end up at the digital happy farm.Why not build it with op-amps instead?Why settle for T when you can have JavaBeans?

author: JoeN
author_rank: Frequent Contributor
timestamp: December 11, 2014, 12:10:50 am
content: I bet you could shove this into a small GAL or PAL with a 555 as a clock. Two chips, 7 resistors, one 7 segment display.

author: Rory
author_rank: Frequent Contributor
timestamp: December 11, 2014, 12:13:53 am
content: Cypress PSOC has T flipflop as a standard part.

author: edavid
author_rank: Super Contributor
timestamp: December 11, 2014, 12:51:12 am
content: Shouldn't you do your own homework?

author: rs20
author_rank: Super Contributor
timestamp: December 11, 2014, 10:46:18 am
content: Come now everyone, can't you recognize a lovely puzzle when you see it? This can be achieved with 6 T flip-flops (unless I've made an error, but I bet 7 tops), assuming those flip flops have complementary outputs. No steering diodes or the like and certainly not a Rube Goldberg solution.However, I have to agree with edavid, this is very obviously a problem created with a solution in mind. Hence, I'm sitting on my solution until we see some working/thoughts from the OP.

author: JoeN
author_rank: Frequent Contributor
timestamp: December 11, 2014, 10:58:35 pm
content: Quote from: rs20 on December 11, 2014, 10:46:18 amWhat I want to know is how you do this as stated, with ONLY flip-flops and not some sort of clock unless you want it to progress through its states so quickly you can't see the output. If this works at all. As stated, this puzzle allows you to use T flip-flops, and a 7 segment LED. I will grant you wire and resistors and a power supply as implied, but nothing else. How this is feasible this is to get something actually working, I don't know, but I do know it would run very fast if it ran at all.

author: rs20
author_rank: Super Contributor
timestamp: December 11, 2014, 11:25:32 pm
content: Quote from: JoeN on December 11, 2014, 10:58:35 pmYou're right to raise this issue, I did assume a clock was available. The problem is just nasty otherwise. I'm imagining that the homework sheet where the OP got this question has a blank space with Ground, Vcc and Clock lines going in :-)Irrelevant fun fact: if you somehow get a T flip flop to self-oscillate very fast, you can use an array of T flip flops as divide-by-2 clock dividers to bring it down to a viewable speed. "Elegant!"