| Electronics > Beginners |
| Project: Long Duration OFF Timer Circuit for LED's |
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| BergRD:
Greets! Wife picked up an antique light that was retrofitted with LED's (3 AA Battery Pack) which looks nice but she would love to have it, alike another lamp she has; has a 4 hour OFF timer. Been trying to find a circuit that I could build that would bring power to the LED's and start a 4-6 hour timer to turn them off once timer hits. 555 and 556 are minutes and beyond the scope (I think) of this project so I have found a few utilizing CD4060 CMOS IC's but wanted to come to the smartest people I know, here at the EEVBLOG! Would the oscillator/binary counter be the most logical? What of the voltage requirements? Will it work or drive 2 standard LED's (Unsure at this point the voltage drop across them but have others could supplement).. More questions as I find info so wanted to get your input. I believe they (online) refer to these as ONE SHOT timers and she has another lamp with a small circuit board and likely a custom rolled IC that already does this (board is about 4mm x 10mm total) and drives a set of 'Fairy Lights' which are those strings of small LED's and hoping I can find something to retrofit this newer piece. Thanks! |
| sokoloff:
--- Quote from: BergRD on August 20, 2018, 02:23:07 pm ---Would the oscillator/binary counter be the most logical? What of the voltage requirements? Will it work or drive 2 standard LED's (Unsure at this point the voltage drop across them but have others could supplement).. More questions as I find info so wanted to get your input. --- End quote --- Almost anyone nowadays would do the timing with a sub-$1 micro-controller. (ATTinys can be had for $0.30 or so.) Add a suitable output drive and you'd be looking at a couple bucks for the parts and PCB. |
| BergRD:
--- Quote from: sokoloff on August 20, 2018, 03:01:09 pm --- --- Quote from: BergRD on August 20, 2018, 02:23:07 pm ---Would the oscillator/binary counter be the most logical? What of the voltage requirements? Will it work or drive 2 standard LED's (Unsure at this point the voltage drop across them but have others could supplement).. More questions as I find info so wanted to get your input. --- End quote --- Almost anyone nowadays would do the timing with a sub-$1 micro-controller. (ATTinys can be had for $0.30 or so.) Add a suitable output drive and you'd be looking at a couple bucks for the parts and PCB. --- End quote --- What's odd is I'm not finding much using micro and I would have thought the same but also haven't worked much with CMOS logic so thought it might also be a chance to expand my own knowledge. I'll have to dig deeper on an pic/arduino/atmel micro route and thought about an attiny micro but was stumped when I didn't find a thousand circuits out on the google near instantly. Did a double take and thought maybe I was thinking incorrectly, lol. Thanks! |
| Seekonk:
At camp I made a 12V fan box and that has a 3 hour timer that turns it off using a NANO. Since the micro doesn't have much to do, the last 30 minutes the fan ramps down in speed before shutting off. I always keep a stock of a half dozen NANO for little projects. I used the RANDOM function in another project to make it look like a flickering flame. Fortunately I have a number od decade timers as we used to build them. Last time I looked at those chip prices they were as much as a micro. There is a lot of simple programming that can create impressive results. Download a free development system and give it a try. An education ought to be worth $3. This is one of my animation projects. It had a ghost plane theme with lots of flickering. |
| sokoloff:
I have an Arduino and a relay board driving a piece of home automation that cycles the relay 1 minute out of every 120 minutes. Took me longer to find a USB power supply in the drawer than to write the code. (It's so simple that may be the reason why it's hard to find the code on google.) In your case, using low power sleep mode is going to be a driving factor in the design (so you don't have to change the batteries all the time). Have a look at pages like https://learn.sparkfun.com/tutorials/reducing-arduino-power-consumption to get a handle on sleep mode and other power conserving strategies. If you can run the AVR directly on the 4 alkaline batteries with just a regular diode in series, you'll be better off than any design that uses a linear regulator. |
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