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Lunar lamp controller, advice pls!

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vitalish

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Hi ALL!

I have to design an automatic lunar emulation lamp. There is some LEDs based lamp that has to be automatically switched On every day at midnight and switched Off at midday. The lunar cycle is 28 days, and the lights output should daily increase from 1 day to 13 day and decrease from 14 day to 28 day. The controller and LEDs lamp power supply should be separated because the LEDs lamp power supply (20W) may be interrupted, but lunar cycle must go on continuously at least several years without interruptions.
Therefore I thought to use some battery powered micropower microcontroller with PWM output in order to dim the LEDs lamp through some powerful MOSFET or bipolar transistor.
The problem is that I have zero experience in microcontrollers programming. Therefore the question is: may I avoid microcontroller usage in this project, are there any alternatives? If I cannot, what microcontroller and suitable tools (I mean compiler, debugger, emulator etc..) do you advice for this application?

Thanks for help!
 

captainhannes

New Member
Now that sounds like a cool project! Thanks for the idea, I will probably build one aswell.

If I do it, I'd like to avoid microcontrollers aswell. Well, I know how to do it with such a bug, but I currently have no eprommer or pic programmer.

I just did a 'far off' project aswell:
http://www.marsbase.net/m/mars-clock.php
I used a 4059 divide-by-n counter for a custom clock signal.
We could probably use this one aswell, but of course we will need some additional dividers to get a suitable clock signal.

I will just go into research and let you know what I find.

Greetings from Austria,
Hannes.
 

vitalish

New Member
captainhannes tanks for the link.
The Mars clock is not far from Moon cycle emulator. And its a good way to avoid micro. I'l look at 4059 chip docs. The only problems i see:
1) i'l need 3-4 ICs for implementation, i'd like less;
2) power consumption may be too high for 2-3year continuous operation with regular battaties

The most sutable micro i found is MSP430 from TI. Its exactly "micropower", very cheap and easy to program device.

Tnx
 

captainhannes

New Member
Well, I have already chosen the 4059 to avoid too many IC's. First I wanted to make a normal modulus divider, but since there is the 4059 I used that :)

Meanwhile I did some calculations:
Assuming one uses a 32768Hz standard clock oscillator, we must do divisions like to following (division no more than 21327, because that is the max. of the 4059:

division by 20693
division by 18037
division by 14

After that and having an accurate oscillator, we have a drift of 0.14 seconds during one orbit of moon and that is negligible.
But the lunation (the time between two successive new moons) varies for about +/- 0.25 days (-> 6 hours), so the display might be not very accurate for single phases, but it will be accurate over time.

Well, doing that without a microcontroller requires at least a number of 6 IC's (3*4059; plus a counter and some to display the phase)

BTW, why must the phase-display run from a battery ???
If that is required, you won't be able to avoid a low-power uC...

Greetings,
Hannes.
 
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