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Dark sensor circuit using LM393 question.... unstable OFF/ON... flickering
- Thread starter johnaustinkaty
- Start date
Thx for the mark up !! I will edit my schematic, then update my board from the schematic and rearrange things on the board as needed. I will post my schematic when done.
Yes, that could be done..... except for the LDD-700L which would get direct 12v as it is currently.
On second thought...No....Unless the LM393 was left at 12v because of headroom (VCC-2v)
But you can move the comparator function into the Atiny and remove the LM393.
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I have added the caps and diodes to my schematic and board. My question is about the fuse. Is it an SMD? What happens if it is blown? Also, eetech00 suggested a way to eliminate the LM393 altogether using a different approach to the dark sensor circuit. I'll look back through the posts and try to find that. I am confident that this circuit will be an extreme improvement from what I had just a week ago. Thx again guys for your help.... Still contemplating using 5v to power this circuit except for the LDD-700L led driver and mini-360. I will post my schematic when finished.
John
Agreed. This also allows me to get the RA red LEDs brighter. I'll have them in series with one 470 ohm resistor. I can dim them down with PWM.
I plan to stick with 12v to the LM393 and use it for the dark sensor circuit with hysteresis. Everything I have been able to test has worked great so far. However, I am still addressing all of your recent additional comments. Maybe additional questions tomorrow as I finish updating my schematic.
hi john,
Ref the fuse, check the attached image
The fuse is located at the battery Positive terminal.
Ref your PM query,
If you powered all the circuit from the MINI-360 ie: 5V, what method would you use to switch the PMOS FET Gate driving the 12v input to the LDD 300, also have you checked the heat dissipation of the MINI with 12V input and 5V output??
E
Attachments
1. Fuse image understood, but still not clear what it's purpose is ?????
2. I am keeping the voltage scheme as is.. no change
3. I have checked for hot spots on the MINI and there are no issues
I wanted to clarify an earlier post:
My light will have a color option for illumination, RED or GREEN, using 3up super bright LEDs. It also has the two 5mm red RA LEDs that will be in series and will require around .028 A.
"The max current of the unit is approx .550 A (green high power LED) when PWM is at 250.
The max current to the super bright 3up LED specifically (green) is around .520 A. The red high power LED needs less at approx .420 A.
The LED driver is an LDD-700L from Meanwell.
.
My light will have a color option for illumination, RED or GREEN, using 3up super bright LEDs. It also has the two 5mm red RA LEDs that will be in series and will require around .028 A.
"The max current of the unit is approx .550 A (green high power LED) when PWM is at 250.
The max current to the super bright 3up LED specifically (green) is around .520 A. The red high power LED needs less at approx .420 A.
The LED driver is an LDD-700L from Meanwell.
.
I have attached my schematic for checking. Thx again!
Attachments
Thank you very much Eric !!! I will make the changes and post the updated schematic. I really appreciate this.
Did I use the wrong symbol for the schottky diodes?
I will be ordering the SS23 schottkey diodes
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Hi
I've modified my schematic in line with the comments below.
1. I've added filter/bypass capacitors (as Eric suggested). These basically ensure voltages remain stable.
2. You've determined that the 1K pullup prevents the power-on flash you were seeing earlier.
It didn't make sense (to me) for the mosfet to control power to the LDD-300 anymore.
So I connected the LDD-300L supply pins directly to the supply rails, and configured a mosfet (2N7000) to
provide a signal to an Atiny GPIO pin as an "enable" control signal for the LDD-300. You can configure the
Atiny to set the DIM pin low/high, or "in-between", to control the LDD-300 OFF/ON/DIM, repectively.
3. I replaced the NPN LED drive transistor with a 2N7000 NMOS.
This reduces the number of different transistors and current requirements.
4. I recommend keeping the PMOS reverse voltage circuit. Its more efficient than diodes.
I've included suggested part numbers for the mosfet and Zener.
5. Lastly, I still think the LM393 comparator function can moved to the ATiny.
These are just some observations and suggestions.
I've modified my schematic in line with the comments below.
1. I've added filter/bypass capacitors (as Eric suggested). These basically ensure voltages remain stable.
2. You've determined that the 1K pullup prevents the power-on flash you were seeing earlier.
It didn't make sense (to me) for the mosfet to control power to the LDD-300 anymore.
So I connected the LDD-300L supply pins directly to the supply rails, and configured a mosfet (2N7000) to
provide a signal to an Atiny GPIO pin as an "enable" control signal for the LDD-300. You can configure the
Atiny to set the DIM pin low/high, or "in-between", to control the LDD-300 OFF/ON/DIM, repectively.
3. I replaced the NPN LED drive transistor with a 2N7000 NMOS.
This reduces the number of different transistors and current requirements.
4. I recommend keeping the PMOS reverse voltage circuit. Its more efficient than diodes.
I've included suggested part numbers for the mosfet and Zener.
5. Lastly, I still think the LM393 comparator function can moved to the ATiny.
These are just some observations and suggestions.
