• 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.

Double Timer, With LED

Not open for further replies.


New Member
Well first off, I'm no eletronics wizard, so if any of you have something to share that will help me with my project, please explain it in laymens terms if possible. :)

Ok, now for the project...

What I would like to build is a timer that counts down from 10 minutes to zero then trigger another timer to count down from 1:30 to zero before resetting the 10 minute timer. The LED I would like to come on DURING the 1:30 while it counts down, but then turn off when the 10 minute timer resets and begins counting down. Obviously a power switch would be nice, as well as a start button which would start from the beginning of the loop (the 10 minute timer).

The start button isn't important as long as the power switch starts it from the 10 minute timer. It would be VERY nice if it displayed both minutes and seconds.

Any help, thoughts, comments, suggestions, etc, would be most appreciated seeing as I've got a very small start without them. :)

Thats the basic idea and thank you in advance to any of you that contribute even a comment. :)

*EDIT* For power, either a battery or a wall plug would be great. :)
*EDIT* Reading through the forums I keep remebering things... It would also be nice to be able to change both timers some how, but I suppose I would have to set them to begin with, so even if it isn't easily done atleast I can change them.


New Member
Rakarin said:
a timer that counts down from 10 minutes to zero then trigger another timer to count down from 1:30 to zero before resetting the 10 minute timer.
So is that [1 hour and 30 minutes] or [1 minute and 30 seconds]?
Assuming you want the exercise rather than a microcontroller (single chip solution) this could be done with logic ICs, either TTL or CMOS.
If a basic clock is constructed form a 555 or a couple of inverter gates to run at 1Hz all that is left is a counter circuit that could drive a 7 seg display and trigger a flip-flop to enable a second counter. The flip-flop can drive your LED and the second counter can drive another 7 seg display.

A [START] button can simply reset all counters and the flip-flop.


New Member
Ahh woops, sorry about that, that would be [ 1 minute and 30 seconds ].

Alright. If possible if you could give me item names which I ought to pick up or order that would be great. I'll definantly be going to radio shack or ordering the pieces I need tonight or tomorrow. :)

As well if you happened to have a diagram I could take a look at it would be very helpful so I can get the idea of where to place everything. If not, I'm sure I can figure it out. :)

Once again, thanks for your help. It's greatly appreciated.


New Member
mechie, sounds to me like all he wants it to do is work, doesn't care about making it himself, so maybe the single chip idea isn't too bad...

maybe give him a part number or two? hehe


New Member
Complex Answers to Simple Problems ?

daviddoria said:
all he wants it to do is work
If you feel writing a PIC program is a more energy-efficient solution to the problem then carry on and give us the choice of circuits to build ... I simply thought that as we don't all have a programmer and that discreet electronics can solve this problem as easily anyway (maybe 4 or 5 CMOS chips?)...

Rakarin I have no circuit to offer yet - I will think more about this tonight and see what I reckon, we should be able to design something fairly quickly :wink:


New Member
Thanks, this isn't to terribly important so don't spend to much time on it.

It's actually for a video game called Planetside. Time for an ingame action. As I said I don't know to much about building electronics from scratch but I'm happy to learn if you guys can give me links or resources I can read.

Thanks again. Rakarin
Not open for further replies.

Latest threads

EE World Online Articles