Post # 43, " 10k to 100k pots "
Might be a good idea to add a 1k in series with input to protect zener.

 

I do have two comments, in fact. If you use the circuit as shown, I suggest using 20K pots for one reason, which is that with 10 2K resistances in parallel yjay presents a 200 ohm load to the regulator, meaning there is more power dissipated and more heat. So 20 K pots will present a 2K load. The second comment is that since all of the setpoints are in a rising voltage mode, you may be able to get away with putting all of the 2K pots in series, which reduces the span of each one by a factor of ten. That would make setting easier, except that you would need to add a series resistance tp each end of the string, because the entire range is only a small part of 12 volts, or 9 volts.
OOPS. Cancel that thought.
BUT you could use a different, lower voltage, regulator for the supply to the pots and make adjusting them easier.
Good thing that I caught that goof!

Hi MisterBill2

I'm not sure which comment to cancel.

Can you clarify please?

thanks

eT

 

Post # 43, " 10k to 100k pots "

Ok...how about the middle of the range....50k pots?

Might be a good idea to add a 1k in series with input to protect zener.

You mean in series with the circuits +12v input?

eT

 

" Might be a good idea." Not such a good idea. wrong input wrong value,
0 to 10 ohms better.

 

Hi MisterBill2

I'm not sure which comment to cancel.

Can you clarify please?

thanks

eT

OK, what happened is that I made an error in suggesting that all of the ten setpoint pots should be in series. The reason that it will not work in this application is that it spreads the setpoint values into segments covering the whole span of the voltages frpm the 9 volts from the regulator down to zero. But in this application all of the voltages are over a much narrower span. So many of the comparator setpoints would not have been within the range that was needed. Fortunately the error was caught before any circuit was wired. Using 20K pots in parallel will still be the best choice. Sorry about not being clear enough before.

 

OK, what happened is that I made an error in suggesting that all of the ten setpoint pots should be in series. The reason that it will not work in this application is that it spreads the setpoint values into segments covering the whole span of the voltages frpm the 9 volts from the regulator down to zero. But in this application all of the voltages are over a much narrower span. So many of the comparator setpoints would not have been within the range that was needed. Fortunately the error was caught before any circuit was wired. Using 20K pots in parallel will still be the best choice. Sorry about not being clear enough before.

Ok...got it...thanks

eT

 

I'm going to back tract & on original drawing make R18 - 25, 3 x value of R10 - 17 so 2k would use a 6k2 in series. Use 2k to 10k pots. Or as earlier suggested, use an additional V reg. of around 3V & just pots.

 

Game is on, got the parts. Few spares as well and all 4 types of LEDs I linked before @ #77. Will see which suits best.
I'll start assembling maybe tomorrow or on the weekend. I go with the drawing @ #75
I got confused with the trimmers for the LM339s and I didn't want to bother you again, so I went with 5K 23turn ones. I figured these go as low as needed or should I need more than 5K, I can add fixed value in series for each ones.
LMV841 in SC-70 (SOT323) will be hard to implement but I'll make it happen.

I'll keep you posted.
Thanks

 

Game is on, got the parts. Few spares as well and all 4 types of LEDs I linked before @ #77. Will see which suits best.
I'll start assembling maybe tomorrow or on the weekend. I go with the drawing @ #75
I got confused with the trimmers for the LM339s and I didn't want to bother you again, so I went with 5K 23turn ones. I figured these go as low as needed or should I need more than 5K, I can add fixed value in series for each ones.
LMV841 in SC-70 (SOT323) will be hard to implement but I'll make it happen.

I'll keep you posted.
Thanks

OK on using the 5K ohm pots. Certainly an additional series resistor will be able to set the range to cover the voltage that you need. Working with surface mount parts without a pc board with traces can be tricky, I did it once using pieces of #24 wire to each pad, and gluing the SMD down to the board. Time consuming but not terribly difficult. You do need a fine tip soldering iron and also a pair of tweezers, and something to hold the part dow with. I used a wooden toothpick.Then you do need to check that the connections are right after you are done.