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Simple help with a 7 segment display

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Ryan Harding

New Member
Hi, im doing a school project which is a counter. I think this is an easy question, that i just need answering :)

I need a simple circuit that when i press a PTM switch once the counter goes up from 1 to 2. When i press it again it goes from 2 to 3.

If anyone could help me by a circuit diagram and components i would be very very greatful :)

Ryan
 

spyghost

New Member
hmmm... sounds like a logic systems class... 8)

if you need to do it using "lots" of ic's, then get a counter (74xx160 or 74xx161, by the way this is a decade counter), a 7 seg driver (74hc4511, or any suitable replacement), some resistors for limiting the current in the led, a debouncer circuit.

if you need something with "few ic's" i recomment using cd4026 or cd4033. both are CMOS Decade Counter/Divider with Decoded 7-Segment Display Outputs. all you need is to cascade these ic's, a seven segment display, and a debounced switch and your done! :D
 

Ryan Harding

New Member
Thanks very much for the help guys, much appriciated.

Reffering to this https://www.aaroncake.net/circuits/counter.htm
Extremely helpful but i have a couple of queries. Im new to electronics so bear with me :p
- Is it possible to do two 7 Segment Displays in the same circuit but operated by different switches?
- What kind of switch does that circuit use? Can it be operated by one press of a simple PTM switch?

Thanks again, Ryan
 

Electric Rain

New Member
Ryan Harding said:
Is it possible to do two 7 Segment Displays in the same circuit but operated by different switches?

Hmm... do you mean, basically just two of them but both running on the same power supply? If so, then yes.
Ryan Harding said:
What kind of switch does that circuit use? Can it be operated by one press of a simple PTM switch?
Weeeell... if you look at the schematic, you'll see "Count in". If you look at note #1, you will see that the "Counts" or pulses, need to be TTL. Now, I'm still quite new myself, but I do believe that in this case, a good idea would be to use a 555 timer. They produce a TTL signal. Use the program attached to find the values of the two resistors and the cap (you'll see when you get in there) depending on how much of a delay you want between the time you press the button and the time it enters the count. (Yeah, there's going to be a delay. :lol: ) If you want it as quick as possible, then use a 1M resistor for Ra, and a 1pF cap for C. But first, set the voltage for 5 volts, then, make sure you go to monostable, not astable. The resistor and the cap set the speed for a 555 in monostable mode and in astable mode. (Though, in astable mode, there is an extra resistor, Rb.) Astable will create a delayed pulse and repeat it over and over from the time you press the button. Monostable mode will create a delayed pulse only once when you press the button. So, needless to say, you'll want it to be in monostable mode. :wink:

Anyway, if you're just getting into electronics then the 555 timer is going to be something you should get to know. They're fun once you get to know how to use them. :wink: Hope all of this helps, again, any questions and I'll be glad to help, err... try at least. :lol: See ya.

Rain

P.S. Can someone else who knows this stuff better than me make sure I'm right about everything I said please? :lol:
 

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Ryan Harding

New Member
Heh, thanks alot, i have used the 555 timer once in a school project.
A Tooth Brush Timer :roll:
Also, does anyone know what resistor i need to use to take a 9v battery to a 5v, as i have alot of circuits built into one project that is using a 9v battery.
Dont flame me for this as im new, but can i work this out by ohms law? Or am i lost :)

Thanks very very much for the help, will go and buy all my parts A.S.A.P and test it out.

Last thing, does anyone use a 'Simulated Programme' or anything of this kind to test circuits? I use one called Crocodile Clips, its pretty basic but im unsure of any others.

Thanks alot again.

Ryan :D
 

Exo

Active Member
Ryan Harding said:
Also, does anyone know what resistor i need to use to take a 9v battery to a 5v, as i have alot of circuits built into one project that is using a 9v battery.

The resistance value required to drop 9V to 5V is dependent on the load (ohm's law). Since you have a constantly changing load (more or less leds depending on the number displayed) you won't be able to use a resistor. Use a voltage regulator, such as the 7805.
 

madauzz

New Member
help on cd 4026

hey any of you guys can help me with the cd4026 counter. im using it in my robot project. can you help me with the correct connection of pins? please reply ASAP!! T.Y.
 
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