This is a little solar DC Motor Driver.

It uses two LDR (Light Dependant Resistor) sensors to track the movement of the sun.

There is no microcontroller, it uses an Op-Amp (Operational Amplifier) as a comparator to switch relays to drive a motor.

With the correct rated relays A Large DC Motor can be driven.

I totally messed up in the video above trying to explain the Logic Gates off the top of my head, due to my memory issues (it is what it is).

You may want to watch the video below first, so that you know where to skip through my video above.

The working voltage of this PCB is 5 volts.

The main components I used in this project where parts I had in my box of bits.

I don't think it is critical that you use the exact parts that I have used.

Some Adjustment may be required based on your location and the amount of sun you get.

The DC Motor driver is based around voltage dividers and the result processed by the Op-Amp used as a comparator.

The reference voltage is set by resistors R1 and R2. Changing R2 can make it more sensitive to changes in light.

R2 can be 4.7k to 10k.

There is a socket for attaching remote LDRs. Using the onboard LDRs requires the solder jumpers to be connected.

There is an onboard 5 volt linear regulator, this can supply the working voltage from the motor power, via a solder jumper.

Note! The linear regulator has a max input voltage. If your motor power exceeds this the a separate 5 volt supply will be needed.

There is a BOM in the zip file, below I have made some notes about the main components.

LDR

I find LDR (Light Dependant Resistor) can be quite hit and miss.

The ones I have used are for my old stock of parts, I have no clue to the make or specification.

The resistance when Dark is around 1M. (cover with black card)

The resistance in use is around 1k to 20k.

To balance the voltage divider we want about 10k in ambient light, so it equals the reference voltage. Pointing at the sunlight it should change from this.

Op-Amp

I have used a NE5532B (over 2000 gain, a little over the top) Operational Amplifier as a comparator.

Any compatible Op-Amp should do.

Vcc is 5 volts.

All it needs to output is below and above the threshold of the Logic Gate.

NOR Gates

I have used the CD4001B Quad 2 input NOR chip, I use 3 of the gates.

Any compatible with 5 volts should be ok to use.

Relay SPDT

The relay I have used is the type you get in Arduino kits.

It needs to have a 5 volts coil.

It needs to be SPDT (Single Pole, Double Throw).

The rating of the contacts should be able to handle the motor used.

The circuit

Me assembling the components

Assembled

Does it Work