• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

solar long delay timer

Status
Not open for further replies.

ajianzzzzz

New Member
Hello there,
I have lots of projects, this is the fist time I need to involve electronics. All the stuff I have looked at from searches seem to be timers for a few seconds or minutes. I need a long delay low voltage timer. I have a solar panel (10v on a good day, (no batteries included or wanted)), bread board and a light sensor.

Scenario-- A light goes on daily, a motor runs for 4-6 or 8 hours (not critical) and then turns off. As a further complication I also need to have a mode that can switch from doing this once daily, to once every two days or more if poss (not critical). I can’t find anything to match these requirments. I have gathered that some kind of programable chip is required on the bread board but the voltage will vary a little during cloudy days etc. Any leads for further info would be a great help. I need to know if this is possible or not. I’m a total beginner but willing to read and learn.
Thanks for your knowledge and time.
 

marcbarker

New Member
Sounds very much like a "PIC project". A PIC is very low power, it can drive a MOSFET on and off easily to control a motor. It has a built-in reasonably accurate timer. The clever PIC geeks on this site can suggest more details.
 

ajianzzzzz

New Member
I hope the PIC people are listening

PIC and Mosfet. That's a good start. I hope the PIC people are listening.
Thanks
 

crutschow

Well-Known Member
Most Helpful Member
Do you have line power available? If so you could use a sprinkler timer controlling a relay. They usually have 14 day independent day and time settings.
 

marcbarker

New Member
You've already got the main Timer, although it's controlled by something 93 million miles away it's quite accurate. After sun-up I gather you want start a timer running. And a switch on the side of it to ignore every other alternate sun-ups?
 

ajianzzzzz

New Member
I only need the sun for the power and it would be on too long for my needs. A light is turned on manually, daily, to trip a light sensor. A timer will run as "on" and after x hours "off". Using the switch to go to alternate days when I need.
 

marcbarker

New Member
Is the "light sensor, (tripped by a manually operated light)" to be an integral part of the proposed timer circuit?

Is the "light switched on manually" to take place at a random time during the day, or is it after a fixed time period, tied to sunrise/sunset?
 

ajianzzzzz

New Member
Yes. It should only operate at the point the light is turned on manually.
There is no fixed time that the light will be turned on but it will be daily.
 
Last edited:

marcbarker

New Member
So, if I have this correctly.

Daylight powers a solar panel, powering the proposed circuit. There is no battery.

Sometime at random during the daylight hours (but not at night time), a lamp is switched on.

A light sensor on the proposed circuit ignores this daylight somehow, but picks up the light from the switched on lamp (ignoring a camera flash) and this is a trigger.

The trigger starts a timer running.

The lamp might be turned off after a few seconds, or an hour, or after sunset. If the lamp is switched on again the circuit is/ isnot retrigerred?

The triggered timer runs for x hours, during which time a mosfet is on.

After the timer has expired, the mosfet switches off.

If a switch on the proposed circuit is set, then the mosfet drive is inhibited every other daylight illumination cycle of the solar panel. Somehow, the circuit must remember which day it was during the nighttime, when the solar panel is dark.
 

ajianzzzzz

New Member
Yes sorry I guess this is s bit criptic. You are getting it though.
You said..
Daylight powers a solar panel, powering the proposed circuit. There is no battery.
Correct.

Sometime at random during the daylight hours (but not at night time), a lamp is switched on.
Correct.

A light sensor on the proposed circuit ignores this daylight somehow (It’s in a sealed box), but picks up the light from the switched on lamp and this is a trigger.
Correct.

The trigger starts a timer running.
Correct. It creates the “on” current for fixed time.

The lamp might be turned off after a few seconds, or an hour, or after sunset. If the lamp is switched on again the circuit is/ isnot retrigerred?
The light will be on for several hours after the timer should have stopped, by which time the sun would have gone down anyway and powered down the curcuit.

The triggered timer runs for x hours, during which time a mosfet is on.
Correct.

After the timer has expired, the mosfet switches off.
Correct.

If a switch on the proposed circuit is set, then the mosfet drive is inhibited every other daylight illumination cycle of the solar panel. Somehow, the circuit must remember which day it was during the nighttime, when the solar panel is dark.
Fantastic. I was thinking something like a servo that changes position each time the curcuit is powered giving a “0” or “1” position. I can choose to switch the servo on or off.
Wow your getting it, I was beginning to think it was impossible.
 

marcbarker

New Member
I do have an advantage, I've been doing design for a long time ;) The first stage and often the hardest is capturing a good requirement specification. I believe the customer should be in the loop and working on the problem too, and that there be a good balance between creativeness and evolution. Also the art of getting the compromise right between what the customer thinks he wants, and what I think the customer wants.

Quite often in my experience, when lesser experienced engineers are doing that, they take a written statement from the customer and then interpret it exactly to the letter (including typos), over-literally. It all becomes too 'contractual' too early on in the design lifecycle, stifling out the creativity and the project resembles a train on the wrong track. If there's any discrepancy in the information, the lesser experienced engineer just out of school does what they think the customer wants, going all 'isolationist' as though they know better. Or you get requirement specifiers compete with one another, trying to get in at the earliest they can in a new project so they can have more control, then the detailers pick it up and complain about silly choices made too early on.

Yes, getting a dialogue going, does wonders doesn't it?

Looks like there's a good requirement spec evolving for PICies to pick up on. I say this a doddle for a PIC Geek to do. As for the "day counter" function (that you were seeing a servo for), there is a non-volatile memory (E²) in a PIC to do that.
 

ajianzzzzz

New Member
Yes I was trying to be concise.
Will I need a MOSFET if the motor is only 3v. The Programmable Integrated Chip should give 5v.
 

marcbarker

New Member
if the motor is only taking a low current , the PIC can drive a small motor directly (the outputs are mosfets too), without needing a mosfet. By 'low' I mean less than 100 mA. I guess it'll be low because the solar panel doesn't make much current?
 

MikeMl

Well-Known Member
Most Helpful Member
In keeping with the "Gathering Requirements" suggestion above, reading the discussion above jogs me to ask:

How much current does the motor require while Starting? Running?
How much current does the solar panel produce in direct sunlight?
With sun direction +-30 degrees off perpendicular to the panel?
Do you expect to run the motor only off the solar panel?
 
Last edited:

marcbarker

New Member
Good points raised.

I suggest at this stage some 'sanity checks' brought in against objective reality, before the requirements become too believeable!

I think it'd be a good idea (if this hasn't happened already) to connect the motor to the solar panel during different daylight conditions and check the motor is actually going to do something.
 
Last edited:

ajianzzzzz

New Member
Thanks to the offer to buy the PIC but that will defeat the object of what I'm trying to do.
Since the motor is only 3v low current the solar panel has more than enough to run it even on very bad days. I have tried it and almost burnt it out.

There is some great PIC programming info on YOUTUBE so I'll be heading over there for now as no PIC people seem interested in giving suggestions. Thanks.
 

blueroomelectronics

Well-Known Member
In keeping with the "Gathering Requirements" suggestion above, reading the discussion above jogs me to ask:

How much current does the motor require while Starting? Running?
How much current does the solar panel produce in direct sunlight?
With sun direction +-30 degrees off perpendicular to the panel?
Do you expect to run the motor only off the solar panel?
Can you answer those questions?

PS what is this for? What load will the tiny 3V motor be driving?
 
Last edited:

ajianzzzzz

New Member
I can't be bothered to explain any more. It is all in the scenario, I only need suggestions for further research. If there was load I would have mentioned it etc.
I'm not getting any info here. I'm gonna head over to YOUTUBE.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top