hi john,
By adding 1K and LED to pin1 of LM393 you will change the LM393 Vswing which will affect the circuit hysteresis and On/Off point.

I would suggest a 100k 10 turn Trim pot, so that you can control the On/Off point.
E
This shows the PMOS switching.
View attachment 361203

So, I should not use the R2 10k from output to vcc, but use a trim pot for R2 to find the sweet spot? R2 is the controlling variable? I'll be able to attach a trim pot and test next week.

 

but use a trim pot for R2 to find

hi john
Do you mean R3?
Depending on where you locate the LDR it will affect the light/dark range, R3 variable will enable you set the required illumination switching level.

E

 

hi john
Do you mean R3?
Depending on where you locate the LDR it will affect the light/dark range, R3 variable will enable you set the required illumination switching level.

E

Oh! So keep the 10k R2 and use a trim pot at R3 where the 39k is now? That will fine tune the voltage needed to the comparator to turn the light on...

 

Oh! So keep the 10k R2 and use a trim pot at R3 where the 39k is now?

hi,
Yes.
A small point, spiders webs, dew condensation etc, can be a problem for the set point
E

 

This trim pot will only be able to be used to establish the resistance required at R3, because ultimately this will be a sealed unit and that resistor will be a fixed SMT.

 

If wasps build a nest on the LDR, all bets are off, right? LOL

 

hi,
How many of these units are you planning to make?
May I also ask who will the end Clients will be?
E

 

 

hi,
How many of these units are you planning to make?
May I also ask who will the end Clients will be?
E

I hope there will be hundreds. The end clients will be homeowners who want to watch deer feed at night, but the main target is hog hunters.

 

hi john,
As I stated, the light that the LDR receives will depend upon the mounting location.
Trees, shadows, leaves etc, in fact the same problems as Solar panels

I would advise some method of adjustment of R3.

E

 

hi john,
As I stated, the light that the LDR receives will depend upon the mounting location.
Trees, shadows, leaves etc, in fact the same problems as Solar panels

I would advise some method of adjustment of R3.

E

I understand. Considering that this light needs to come on "around" dusk, it won't be critical. I will also clearly state in the instructions that artificial light on the sensor should be avoided. Placement and orientation of the light will be up to the client to insure proper operation. I will have the circuit designed to power on at the ideal light level at dusk, with no artificial light interference.
This light will typically be located in an area with little or no lights nearby.

 

hi john,
By adding 1K and LED to pin1 of LM393 you will change the LM393 Vswing which will affect the circuit hysteresis and On/Off point.

I would suggest a 100k 10 turn Trim pot, so that you can control the On/Off point.
E
This shows the PMOS switching.
View attachment 361203

Here is my latest PCB and schematic. FYI, I added circuitry as suggested by sghioto to eliminate the bright flash from the high power LED each time the unit is powered on (PMOS is switched) at dusk. All comments are welcome and thank you for the help.

 

The schematic for my circuit is drawn incorrectly?
C3 should be connected from pin5 to ground on the LM393.

 

The schematic for my circuit is drawn incorrectly?
C3 should be connected from pin5 to ground on the LM393.

I'll take a look, thx

 

I'll take a look, thx

Is this better?

 

Is this better?

The schematic is correct but the current pcb layout is not.
The layout in post #52 is correct.
BTW, have you actually tried the circuit to see if it works correctly?

 

The schematic is correct but the current pcb layout is not.
The layout in post #52 is correct.
BTW, have you actually tried the circuit to see if it works correctly?

Not with the new part you provided that delays the LDD-700L. The rest is already on a PCB and is working perfectly in several of my units. However, I am still adjusting R7 to have the light come on when I want around dusk. I will try testing that circuit on a breadboard, but I need to find mine or get a new one. I may have lost it in a recent move. I'll review the PCB and see if I can find the discrepancy. Thx!!

 

Just to be clear this is the correct pcb layout.

 

Just to be clear this is the correct pcb layout.
View attachment 361415

So, this board layout is correct now, right?

 

Dark sensor test results last night:
I had one unit with a 12.2k resistor at R7. Another unit had a 22k resistor at R7. What surprised me is the one with the 22k resistor came on approx 30 minutes before the one with the 12.2k. Should that be the case? They both had the same ambient light level as far as I could tell. I will try the same test again this evening with the lights swapping location. I will also have a unit with a POT attached to R7 and see what it tells me.