You do not seem to have read what I wrote in red in my previous post.Suraj143 said:What an expression now only I understood what’s the meaning of threshold voltage. The threshold voltages are the voltages at which the output of the Schmitt changes state. There is an upper threshold Vt+ and a lower threshold Vt-. When the input voltage of a 74HC14 rises to Vt+, the output goes from high to low. There is no change, if the input voltage rises further. However, if the input voltage is reduced, there will be no change until it falls to Vt-, then the output will go from low to high.
Ijcox don’t scold me (I did not think I was scolding you) for that LM358 circuits output I connected the base of the 2n2222 via 33ohm resister. I assume that this is resistor R4 in the circuit you gave us a link to. Is this correct? Now I have to use a 2N7000 n channel one as you said.
But do I need a base resister for that?
I said that you could put a red LED in series with the base resistor (R4) which should make the transistor switch off when the output of the LM358 goes low. And I would change R5 to 10k. 1k is unnecessarily low.
This would be easier than buying and installing a 2N7000. FETs have a gate, not a base. You could use a 100 Ohm gate resistor (ie. make R4 = 100 Ohm) and you don't want or need R5, ie. remove R5.
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