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.

Adjustable meeting timer with one minute warning

Status
Not open for further replies.
Modulo 6 means that the counter counts from 0 to 5, ie. 6 ststes.

It and a decade counter are required to count the seconds.

There will be some complications if you want to include the Thumb Wheel for the seconds. But it is not impossible.
 
ljcox said:
Modulo 6 means that the counter counts from 0 to 5, ie. 6 ststes.

It and a decade counter are required to count the seconds.

There will be some complications if you want to include the Thumb Wheel for the seconds. But it is not impossible.

Why do it that way and not just use the same counter but input seconds as its clock and make it count from 0-9?
 
johnsoax said:
ljcox said:
Modulo 6 means that the counter counts from 0 to 5, ie. 6 states.

It and a decade counter are required to count the seconds.

There will be some complications if you want to include the Thumb Wheel for the seconds. But it is not impossible.

Why do it that way and not just use the same counter but input seconds as its clock and make it count from 0-9?

Because you need to count from 0 to 59 (or vice versa if you want it to count down) for the seconds. So you need a decade counter and a Modulo 6.

The minutes counter counts from 99 to 0, not 59 to 0. You would need it to count from 59 to 0 if you wanted to include an Hours counter also.
 
ljcox said:
Because you need to count from 0 to 59 (or vice versa if you want it to count down) for the seconds. So you need a decade counter and a Modulo 6.

The minutes counter counts from 99 to 0, not 59 to 0. You would need it to count from 59 to 0 if you wanted to include an Hours counter also.

I drew it the way that I am thinking, we will see if it works, if not I can change it. I didn't draw the 7-seqment controllers because I am doing this in Powerpoint and those are pretty straight forward. I'm just going to have the outputs run to the 7-seqment controllers and have them output all the time.

Relays R0 and R1 are SPDT and R2 and R3 are DPDT.

IC1 is in decade mode with an input of 0, IC2 is in Decimal mode with an input of 6 (it probably needs to go to 5, yes it does, but I'm not redrawing it right now ;)) Or I have to figure out what you are talking about with the Module 6.
 

Attachments

  • Circuit_114.gif
    Circuit_114.gif
    15.5 KB · Views: 1,342
Alex,
No you don't understand the meaning of Modulo. Modulo is used for numbering systems.
Some examples:- binary is Modulo 2 (it has only 2 digits 0 & 1), Modulo 10 is the decimal system (digits 0 to 9), Modulo 16 is the Hexadecimal system (digits 0 to F).

The circuit you have drawn is a Modulo 10. It will start at 6 and count down to 0 and then continue counting down 9, 8, 7 etc since it is a Modulo 10 counter, not a Modulo 6.

To make a Modulo 6 down counter, you have to design it so that when the count reaches 0, it jumps to 5 at the next clock pulse. So it counts 5, 4, 3, 2, 1, 0, 5 ,4, 3 etc.

See the attachment below. This is a Modulo 6 down counter

Why do you want to use relays? CMOS logic would be more energy efficient and require less space.

If you want to use relays, you can make some savings. Relays R0 and R1 are not necessary. the "Zero" signal can drive R3 directly and the "One" signal can drive R2 directly. When I say directly, I mean it in a logical sense. You will need 2 transistors to physically drive the relays.

The Green LED will be on continuously until R2 operates. You wanted it to light when the Start button was pressed.

If R2 operates but the circuit is reset before R3 operates, R2 will remain operated.

Len
 

Attachments

  • Modulo_6_Counter.gif
    Modulo_6_Counter.gif
    6.6 KB · Views: 1,484
ljcox said:
Alex,
No you don't understand the meaning of Modulo. Modulo is used for numbering systems.
Some examples:- binary is Modulo 2 (it has only 2 digits 0 & 1), Modulo 10 is the decimal system (digits 0 to 9), Modulo 16 is the Hexadecimal system (digits 0 to F).

Thanks I get it now! I assumed that the chip that I had just reset to the inputs, but I wasn't counting on that anywhere else, so I must have had a brain freeze.

ljcox said:
Why do you want to use relays? CMOS logic would be more energy efficient and require less space.

If you want to use relays, you can make some savings. Relays R0 and R1 are not necessary. the "Zero" signal can drive R3 directly and the "One" signal can drive R2 directly. When I say directly, I mean it in a logical sense. You will need 2 transistors to physically drive the relays.

I was planing on using large LED's and I wanted to keep the LED section seperate from the logic.

Unless I'm mistaken, the counter isn't going to stop when it hits zero, so the lights will only stay on as long as both of the counters output zero (or the one outputs one). If this is the case, the lights will only be on for a little bit. As I said, I'm a power systems engineer and relays are what I use everyday, I forgot about useing transistors as "relays".

Size is of no concern (meaning that the box that it is in will probably be bigger than the circuit) and I found a 12V transformer/wall wart in the basement that should be able to supply plenty of power.

ljcox said:
The Green LED will be on continuously until R2 operates. You wanted it to light when the Start button was pressed.
There you got me, I decided not to install a fifth relay tied into the start button to keep the relay count down.
ljcox said:
If R2 operates but the circuit is reset before R3 operates, R2 will remain operated.
And that is because I put the reset button in the wrong place. :)
 
Alex,
This is the way I would do the control. Note that the counters only count when O1 is High.

You can use transistors to drive the LEDs.

Len
 

Attachments

  • Control_cct.gif
    Control_cct.gif
    8.9 KB · Views: 1,314
Hi ljcox,

Best of luck with it,

Regards, John :)
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top