Hi,
I am trying to mod my de-soldering station by adding in a small tank to hold a vacuum, and a solenoid is actuated after a certain amount of time allowing the gun to have a decent burst of negative pressure instead of the slower build up. After 1.5 seconds or so the solenoid will open and hopefully suck all the solder out so the bad parts can be removed.
Anyway, I have designed this circuit using one of the LM339 comparators as a schmitt trigger, then using another comparator on the chip to invert the signal to use on a transistor to trigger the coil. I don't understand what is happening with the circuit. The inverting input on U2B is going below the reference voltage and the output doesn't change until the trigger is released. The trigger is normally open as per the diagram.
Thank you for your assistance.
I am trying to mod my de-soldering station by adding in a small tank to hold a vacuum, and a solenoid is actuated after a certain amount of time allowing the gun to have a decent burst of negative pressure instead of the slower build up. After 1.5 seconds or so the solenoid will open and hopefully suck all the solder out so the bad parts can be removed.
Anyway, I have designed this circuit using one of the LM339 comparators as a schmitt trigger, then using another comparator on the chip to invert the signal to use on a transistor to trigger the coil. I don't understand what is happening with the circuit. The inverting input on U2B is going below the reference voltage and the output doesn't change until the trigger is released. The trigger is normally open as per the diagram.
Thank you for your assistance.