I've been trying to put together a circuit that will turn a dc motor in one direction when there is no light and turn the other direction when light returns. I'll have shaft attached to the motor that moves an object to the left and then to the right. When the object reaches either side, I need the motor to stop, until it needs to go in the other direction. I'm guessing a micro switch on the ends may work somehow, but I’m not sure. The motor operates on 1.2v battery which is charged from a solar panel, similar to solar lights I guess. Can anyone help?

 

how about using say two 9volt batteries at most for a circuit to control the 1.2 volt battery? Guess you cant charge the 9volts without more circuitry but Seems to be a harder task to use 1.2 volts to do all this you want to do. maybe someone else can do it. My thoughts are to use an H-bridge to control the motor drive, an led shaved down or a photodiode for the detector of the sun and a quad op amp to do switching and timing. Of course there are more ways, great thing about electronics, there are more than one way to do it.

 

Yes I could use a 9v to power thisor even 2 AA, I'm just wondering if a small solar panel would charge it back up (within 4-5 hours) enough to continue operating. Any thoughts? I'm just not great at putting it all together, but I can follow instructions.... So I'm looking for any help at all.

 

Hi,

Looking like you is after a kind of Solar Tracker? I am working to build my own solar tracker using some diodes and solar detection method.

Let me know if it is this you is looking for?

 

oh is that what you are trying to do? I have seen a complete diagram for a tracker. would be easier to take a look at one of those if that's the case. Let me know as well and I will locate that diagram.

 

Is this a solar tracker or curtain runner??

 

oh is that what you are trying to do? I have seen a complete diagram for a tracker. would be easier to take a look at one of those if that's the case. Let me know as well and I will locate that diagram.

Please share that diagram or link where you have seen it. Thanks

 

it's more of a curtain runner. But I haven't found any schematics for it.

 

You will need to modify your specifications a bit.. It is very difficult to run everything on 1.2v.. I have a plan in mind but needs atleast 6V to run a relay and a 555..

 

If you use 6v, you can also recharge the batteries but would need also an LDR for light detection..

 

I'm open to any suggestions. I'm just try to keep the solar panel small, say 3-4 inches square.

 

How much power [ mAHrs.] does it take for one way travel? Then you will know size of solar panel required. I would op for 3.6 V battery, use PWM to make motor think it had 1.2V. Solar panel will give light-dark sensing. Relay OK but coil does draw more current than H bridge vs simplicity.

 

I'm not sure how much power it uses or even how to figure that out. I was also thinking of running everything off of 3.6v. And from what other people have mentioned, it sounds like the H bridge is the way to go, I'm guessing. Actually mentioning 3.6v, I have a 3.6v cordless screw driver that does charge anymore, but the motor seems to work fine. Great idea.

 

Well Here's my idea... I havent tested it, but must work. Try a simulation if you can.

You can add your solar panel at the input. I see no way to run it on 1.2V.. You will have to supply 6V to use this circuit.. Supplying lesser voltage prevents the relays from latching and higher voltage causes both the relays to latch at power on. Hope this is what you want. Also for a 1.2v motor to run on this, use a sufficient wattage resistor in series with the motor.

 

Would it be possible for this to work on 3-3.6v, If I changed the relays? I noticed digikey had some low voltage relay. But I wasn't sure about the coil voltage, coil on voltage, and coil off voltage. As I mentioned earlier, I'm somewhat clueless. I was also wondering does or will anything in this circuit drain the battery when the sun is out and charging the battery?

 

The matter is, 555 works only from 5-15V and the CMOS version gets that to 4.5v minimum. And at that voltage, there is no relay( i guess) to match the drive voltage. If you are worring abt the current draw, read this

As the motors and relays would only operate when the light condition changes, current required wouldn't be an issue..

Current draw during standby by 555 at 6 Vcc would be 5-10 mA
During pulling curtain, relays would take abt 20-50mA and ONLY one relay would work at a time.
Motor pulls abt 200-250mA at start and 120mA at run.

So at standby current draw is 5mA
At peak running, draw is max 50mA

Just the supply voltage is the issue. Just for curiousity, why are you sticking to that 3.6v battery?? Any preferences??

The circuit will keep the IC running at all times drawing 5mA as it is necessary for light monitoring.Whatever circuit you build, that draw will be there. The relays ONLY work when the motor runs, i.e, the curtain is being pulled, which is unavoidable. You can transistorize this circuit, but wont have much advantage over complexity other than lower current consumption. 5mA is ok as it would be like lighting up an LED at quarter the current.

 

I had made a small design mistake in the diagram. It is now corrected. Before you build the circuit, just connect the inputs of both the relays in series to the 6v you are going to use and see if both of them gets energised together on power on.If nothing happens, your relays are perfect for this circuit. If they do so, add 2 1N4007 diodes in series and test again. You will have to use one diode for each relay in series when building the circuit. Its is due to the variation of power on voltages of relays for different manufacturers.

I never thought I could ever design a circuit utilizing all 8 terminals of a relay. First time!!

 

I was just trying the 3.6v because I can't seem to find a small 6v solar panel that measures 3-4 inches (L & W). Others have suggested using and op amp as a comparator with and h-bridge, but I have no idea what the differences are. The whole reason I'm looking for help.

 

solor tracker corcuits
http://www.phoenixnavigation.com/ptbc/articles/ptbc55.htm
http://www.redrok.com/electron.htm#led3x
http://pages.prodigy.net/rich_demartile/
http://sunenergyworld.blogspot.com/2006/10/sun-tracker-reloaded.html
also you can search the patents for the devices and get schematics there too. I started a search for movable shades but ran out of time here is one of the patent numbers you can use and put in the search bar of the patent search bar. 4557310 patent number ,this link will take you there.

 

If the CMOS version 7555 is available for you, then you could try that.. It works from 1.5volts.. when you use it on 3V, add a 1N4001 diode in series with the 3.6v battery to drop the voltage to about 3v.. Then you can use two 3v relays.. Are 3v relays and 7555 available for you??

The 555 section can also be replaced by a transistor pair eliminating the need for a 6v..

Can try solar bot type circuits too.. They have photo detectors for direction tracking and a motor for drive control.. minor modification might do...

Or you can go op-amps with H bridge or PWM.. H bridges require 2-3 volts higher than your motor voltage. which gives 3.2-4.2v... Hmm... give it a try..