Hi all, I posted this question as a response to an earlier post but not sure if that buries it so thought I'd post as a new topic, I hope that's not bad forum etiquette.
I'm trying to make the soft latching circuit from project #262, I've attached an image.
I've had to replace the IRF9110 with a (hopefully equivalent) MOSFET, I've used an IRF9160 (datasheet attached) as from googleing this is the replacement for the IRF9110.
What I can't understand about the circuit is why it would turn on when power is supplied first. I would have thought that as the gate is tied high at first it would be off then when the switch is pressed and the gate of the left transistor is brought high and it makes a connection to ground it would switch the MOSFET on and latch?
The problem I am having is that when I first apply power to the circuit the output is off, when I press the button it switches on and latches, then that's it, it stays latched on even when the button is pressed. I have to make a direct connection to ground, not through the transistor to turn it off.
The only difference between my circuit and the one in the video is that I'm using the IRF9160, my power source is 4x 1.5V AAA batteries, I used two initially but this did nothing.
Any help would be very much appreciated.