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LED timing circuit for homemade important project!

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Andrew.L

New Member
Hi everyone, I hope you can bear with yet another novice in this field as having looked through the website, there seem to be plenty of us so I hope your patience can hang around long enough for you to answer my questions as well!

I am looking to set up a timing circuit where 24 LEDs are lit up one by one every half an hour and then for them all to go out half an hour after the last one is lit (would this come under resetting a counter? Counting Circuits. As each one is lit, the bulb(s) prior to it should remain lit. I would also like to set this circuit up with a LDR so that during the day light hours the LEDs are not on, however the timer will continue to run so that when power is restored to the LED by the LDRs resistance falling the LEDs will come on at the correct point in the sequence.

A point to note is that these LEDs are representing a clock face and so it is vital that they stay in time with real time. Does anyone know how to connect a real time clock/ counting device to the LED circuit? It would be fantastic if the timing module could adjust for daylight saving automatically but this is not critical.

Last but not least I intend to run all of this from a solar panel if this is possible. If it is could anyone recommend the rating of the solar panel I may need.

My research has thrown up a few possibilities however I do not know how correct/incorrect they may be! A 555 timing chip could somehow be used or something similar to this timing chip Universal Timer Kit : Timer Kits : Maplin but with a longer time period.

Thank you so much for any help you can give me! I've come to the end of a long and confusing research path so any tips/directions to go would be of fantastic importance!

Andy. L
 

k7elp60

Active Member
Some helpful comments: If you want the clock to light up after dark and be powered by a solar cell you will need some kind of a rechargeable battery for the solar panel to charge as it doesn't generate a dc voltage in the dark.
You will need a divide by 24 counter that is clocked with an accurate time base every 30 minutes. The divider will need some form of decoding for each output every 30 minutes in sequence.
 

mbarazeen

Member
you can use 4017 counter cascaded to light one by one, also for time base you need a high frequency crystal oscillator and then have to divide it by some divider so achive 30min time interval, i have already done some project based on both, will post you shortly the circuit when i am back home.
 

mneary

New Member
If you want the clock to be powered by solar, it must have access to direct sunlight for most of the day. There is simply not enough indirect light to generate a useful amount of power.
 

mbarazeen

Member
for solar power better use a inline battery so that it can serve during night time too,
for time base see the attched diagrames, one of them is a part of an inverter that use 50Hz time base, you can use the same oscillator and divider with another extra divider to get required time pulse, 30min etc.
the 2nd attachment shows how you can connect two 4017 counters to get more than 10 lights, you even can make it by three ICs to get 24 stages and reset by the 25th out put.
 

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