astable mutivibrator to a display

[ericgibbs]

haha.oh wow,will do.I'm studying at UPE(now called Nelson Mandela Metropolitan University).I'm actually from Johannesburg,just in PE to study,less distractions at PE than in Johannesburg...By the way,could you help me with that simple resistor/transisto/LED design,could you do a schematic of it,please,just a rough idea.
Thanks eric

hi,
Looking at your first post, I think you are asking for a simple timer, for about 30 minutes.???
Have you already bought any components for the 'original' circuit.... BTW. dont build that original circuit.!

 

[Christy]

hi,
Yes,just to show the status of the counter.no i haven't bought the components yet.I believe there are some defaults in the circuit,what can I do to overcome them, before a bad situation happens?

 

[ericgibbs]

hi,
Yes,just to show the status of the counter.no i haven't bought the components yet.I believe there are some defaults in the circuit,what can I do to overcome them, before a bad situation happens?

hi,
We will post some suitable circuits.

 

[Christy]

Thanks a lot ,sir.

 

[ericgibbs]

Thanks a lot ,sir.

Hi,
Look at this option, approx every 1800 secs the beeper will sound for 50 sec.
The beep and 30min timing can be cleared/restarted with a Manual Reset Sw.
Note: the piezoelectric sounder is the type that will generate a tone when a voltage 5V thru 12V is applied.

Do you need the pin numbers for the IC or can you work that out.?

 

[Christy]

Hi Eric,

No Sir,I will find the pin numbers out myself.
Thanks a lot for your help.

 

[ericgibbs]

Hi Eric,

No Sir,I will find the pin numbers out myself.
Thanks a lot for your help.

hi,
If you use LED's, this circuit will drive an LED.

I would also consider fitting a switch in the LED's supply line, it will help save the battery.

 

[mohd ezwan]

hi,

I had a same problem with Cristy. This schematic diagram cannot run. I need some help from you guys. Can someone show me the real schematic diagram for this circuit. I really need your help. I have to submit this project on this Friday.

 

[ericgibbs]

I had a same problem with Cristy. This schematic diagram cannot run. I need some help from you guys. Can someone show me the real schematic diagram for this circuit. I really need your help. I have to submit this project on this Friday.

hi,
Look at post #25 for an alternative circuit.

 

[yesyes]

Alternatively, please specify EXACTLY what you expect the circuit to do.

 

[mohd ezwan]

hi,

Eric,thanks for the circuit. I will try my best.
yesyes,i want this circuit function like this-->It helps to prevent them from dozing off while studying, by sounding a beep at a fixed time interval, say, 30 minutes. If the student is awake during the beep, he can reset the circuit to beep in the next 30 minutes. If the timer is not reset during this time, the circuit will switches off the light and fan in the room.

 

[yesyes]

Is this some king of school / study project? It wouldn't make much sense in the real world. The requirements made me smile. So let's try to keep that student awake and if it doesn't work, let's at least switch off the light so he can sleep properly... ;-))

The first part is easy and you should be able to do this with a 555 timer IC. You only need to calculate the capacitors and resistor to get the timing you need. Then you need some simple logic that switches off lights and fan if a button has not been pressed while the 555 output was high.

If you want to include a little bonus, you can think of a way to restart the time after the light has been switched off without powering down the circuit first... ;-)

 

[mohd ezwan]

Eric & yesyes,can you explain to me a little bit about this circuit.

 

[ericgibbs]

The 555 is an Astable multi-vibrator, its output clocks a 7 stage 4024 Binary counter.

The 4093 NAND gates decode the 4024 for a count of approx 30 minutes, the beeper sounds after 30 mins for approx 50 seconds then the 4024 restarts a 30 min count

NOTE: the simulation used a C2 of 22uF, in an actual circuit C2 would be 220uF.

OK.??

The smaller circuit is for an LED driver.

EDIT: the manual RESET Sw is a normally open switch

 

[mohd ezwan]

Ok thanks Eric. One more thing sir, I would like to know:

1) These 4 things (cd4000, tone, 5 to 12V beeper, manual reset switch) which I do not sure about it connection?

2) Are these two circuits requiring two different power supplies?

 

[ericgibbs]

Ok thanks Eric. One more thing sir, I would like to know:

1) These 4 things (cd4000, tone, 5 to 12V beeper, manual reset switch) which I do not sure about it connection?

2) Are these two circuits requiring two different power supplies?

The CD4000 is just the series of the HEF or CD4024 IC thats required for that simulation, just use a HEF4024 or CD4024...
Only one power supply is required for that circuit, BUT if you add relays you may require a second voltage.

The piezo beeper is the type that beeps when it has +5v thru 12v across it.

OK.

EDIT:
This circuit should be easier to follow.

 

[mohd ezwan]

sir

Sorry for the late reply. oh,now i got it. Thanks a lot eric. I really appreciate it.

 

[mohd ezwan]

eric

Sorry Eric..i've got one more problem..can you explain the circle in the picture that i send to you..the clock pulse split into two? or is it in the ic?

 

[ericgibbs]

Sorry Eric..i've got one more problem..can you explain the circle in the picture that i send to you..the clock pulse split into two? or is it in the ic?

hi,
Its in the IC, refer this image.

 

[mohd ezwan]

Thanks Eric. I really really really appreciate it. thanks again.