Solar Tracker Using 555 timer

[sle7in]

Yaya...let us be friends...this forum actually help many people with their problem especially me...I can learn many thing here...you all help me a lot...but...things have going so confusing lately...hehe...I'm thinking which one is the right circuit for my project...which one got problem dragon????huhuhu...

 

[Mr RB]

I saw it. Also noticed the title on the drawing But you have to go out every night and point your array back to the East. Um...

Sure. But in many solar tracker designs the actual solar "tracker" part is not responsible for the solar panel return. That is not controlled by the sun position at all and is often a separate system. And that separate return system may even be shared for many trackers.

Generally you have a separate system that detects when it is very dark and manually returns the solar panel to East. In this case where the goal is extreme simplicity I would use another LDR to detect "very dark" and a transistor/relay to run the motor reverse until it contacts a limit switch at east.

Total design would be 2 transistors, 2 relays and a few discretes.

 

[BrownOut]

I don't think the only consideration is simplicity or part count. Some of the solutions may offer more than the absolute minimum requirements for a simple tracker, but aren't necessarily over complicated and may perform better when conditions are not ideal. The costs in are not high either in terms of dollars spent or reliability. A couple decent relays can cost way more than a handful of IC's, and are less reliable. So, simpler may not be better in this case.

I would not use a "very dark" indicator; rather I would implement one of the simple bidirectional schemes. This would be much better on windy or partly cloudy days, and would reset the system at sunrise, if set up for that. That way, you have better control during non ideal conditions and get the reset functionality in the bargain.

 

[Dragon Tamer]

... you lost me there BrownOut, but i think that you're right about the relays. i'm just making rough guesses here, if te tracker can rotate a full 180º and it travels the full distance every day, then if the tracker travels...say...3º at a time, that would make 60 cycles on the relay per day. most relays i work with have an expected life of 10,000 cycles, but if treated properly and shown tender loving care, they can last for up to 1,000,000 cycles. problem is you're not giving it tender loving care, you're making the circuit and chaining it up out back for nature to do as it would. relays, bad idea. the problem with almost (if not all) electronic parts is their opperating temperature. i can only assume that this racker is going to be in decent opperating conditions. also you mentioned something about resetting the circuit at dawn, what about at dusk?

sle, to answer your question, it's the circuit in post #29

 

[sle7in]

Is it the right circuit or has a problem with it???

 

[Mr RB]

Better to reset the circuit in dark. That way you can use a very small slow and energy efficient gear motor, there is no requirement for fast translation since the max speed it ever needs to move is 120' over about 10 hours.

In the one transistor circuit I posted you could easily replace the relay woth a power transistor, then use a hysteresis feedback resistor to make it stop/start or even just let it run linear with the motor turning very slow and tracking the sun exactly.

 

[BrownOut]

I would not size my motor to be just big enough to turn the array 120 degrees in 10 hours. Positioning and holding the array in breezy conditions will be the determining factor. A couple minutes is sufficiently fast enough for the reset function, and woule most likely not require a bigger motor than what would be required to operate the system.

At 60 cycles/day, the expected 10K cycles is used up in only 167 days. That fact would completely eliminate relays for this project IMO.

 

[Dragon Tamer]

Is it the right circuit or has a problem with it???

i was having trouble getting the circuit to work properly, so i just gave up on it. it was too sensitive to the light coming in, and it was constantly changing directions when the sensors are equal.

 

[BrownOut]

If I remember your circuit, you don't want both sensors in the sunlight at the same time. The shadow mask must be designed to prevent that condition. You also need to have some "sunlight hysterisis" built in to your system to prevent oscillations due to system inertia.

 

[sle7in]

OK..nevermind...I'll try to construct the circuit 1st..

 

[Dragon Tamer]

true BrownOut, i will look into that problem right away.

 

[Mr RB]

I would not size my motor to be just big enough to turn the array 120 degrees in 10 hours. Positioning and holding the array in breezy conditions will be the determining factor. A couple minutes is sufficiently fast enough for the reset function, and woule most likely not require a bigger motor than what would be required to operate the system.
...

I wouldn't use a motor that took 10 hours either, but I would be temped to use a gearmotor with some pretty high gearing that might take quite a while to turn the full way back. With so much gearing the wind wouldn't move it anyway and you can reduce the motor current requirements.

...
At 60 cycles/day, the expected 10K cycles is used up in only 167 days. That fact would completely eliminate relays for this project IMO.

I get your point, but I've used relays often over the last 30 years and I have never seen failure at 10k cycles from any of them. I've done a couple of incubators switching 240v AC faster than once a minute, which have seen good service almost continuous for years, one over ten years. That relay has over 2 million cycles on it and will go for many years more. When I worked in industry there was relay equipment there that operated every few seconds and had been going 24 hours a day for many years. Any decent quality relay run without too much arcing has a lifetime measured in millions (multi millions) of cycles, not 10k!

I've seen a lot of failures in power transistors and SCRs too, so the attitude that relays always fail in a few months and solid state always lasts forever is just bunkum. I would give either approach a good 10 years expected life probably with an equal chance of failure provided they were run well within limits.

 

[BrownOut]

That would be alot of gearing. Now, you've spent all your savings from your simple circuit on a gearmotor, which ani't cheap, unless you're buying very low quality chinese motors. And you would be just hoping the motor has enough inertia to hold the system in wind.

the attitude that relays always fail in a few months and solid state always lasts forever is just bunkum.

What attitude? Who made that claim? I only said relays are expensive and not as reliable as solid-state. It not a matter of this thing or that thing always happening, but a matter of MTBF for active devices, or MCBF for relays. I don't know why anyone would have problems with transistors or SCRs, I've used triacs to control banks of 2500 watt resistive heaters for military spec testing, and don't remember ever having any failures.

I have to stick to my earlier statement that there isn't a single solution that's always superior to the others. It depends on the whole system, specific requirements and other factors. All of the proposed solutions are good ones, IMO, and make good candidates when considering your design.

 

[AllVol]

Sometimes in our eagerness to be the first to problem-solve, we overlook all the information available.

I'm sure that explains why you failed to check out the web-site of a person who has dealt with all these questions and more, and adequately solved them.

This link first appeared way back on page two, but in case you missed it http://www.josepino.com/lego/simple_sun_tracker

 

[Mr RB]

...
What attitude? Who made that claim? I only said relays are expensive and not as reliable as solid-state. It not a matter of this thing or that thing always happening, but a matter of MTBF for active devices, or MCBF for relays. ...

I wasn't talking about your personal attitude BrownOut so much as talking about the "fashion bigotry" that's been coming up on the forum lately. Like now that Lithium poly batteries are fashionable "no other battery should be used" and similar attitudes about relays etc. It's just a personal gripe of mine that many people jump to embrace any new technology and start saying the old technology has become "crap" and shouldn't be used anymore. I'm miffed that I can't buy lead solder, NiCd batteries, even 240v light bulbs now. Again some idiot decided the new stuff is good and the old stuff is no longer any good. Just put it down to me being a grumpy old guy haha.

AllVol- I don't think Jose Pino's solution is "adequately solved" because he's not using a balanced sensor, so his sensor requires sunlight of a particular strength. You can see he had to put cardboard over 80% of the sensor to make it work, so in cloud or winter etc it is not going to work right. I really think you need a balanced sensor so it cancels any lighting effects and still points direct at the sun even if it is a dimmer sun etc.

 

[BrownOut]

Heh! Thanks for clearing that up. I agree with you actually.

 

[killivolt]

Heh! Thanks for clearing that up. I agree with you actually.

Speaking of technology I guess this is older still not used that much?

Maybe I have it wrong. I don't know but, the subject came up and one of my tech's mentioned this.\

Vanadium redox battery - Wikipedia, the free encyclopedia

 

[solarman]

hi sle7in

I'm very interested with you're work I'm just curious if you succeed with this project of you'res? I've already done solar tracker using Pic but there's still a problem with it thats why I want to try it using 555 timer..can you give me the whole schematic diagram of you're project?Thank you in advance

 

[4pyros]

This could be done using two 555 driving a DC motor in an H bridge and 3 or 4 LDRs hooked up using the 555 inputs at 1/3 levels. I just have not seen it before.
Andy

 

[gary350]

the

You can probably use something other than a photo cell. Some type of photo circuit that will close a relay and turn on a low RPM motor. Every time the sun shines in the bottom of the funnel the circuit turns on the motor and it moves forward out of the sun then stops. It moves forward all day long over and over moving out it the sun. At the end of the day it stops moving and at midnight a clock returns it to the starting point for the next day.