Hello everyone!
During experimenting I ran into the following problems. I built a gated astable from nand gates which is turned on and off by a nand bistable. The circuit can be seen in the attachment called 'circuit1'. As you can see the bistable is interfaced to the astable via an n-channel mosfet. The two diodes make sure that pulse completion occurs when the bistable is flipped during a high astable pulse and therefore the pulse is not shortened. This circuit works as it is supposed, I have tested it on a breadboard. However, I am not sure if the pull-down resistors marked R5, R6 and R11 are needed, if someone could help with this small question, I would greatly appreciate it.
My other problem is that I tried to omit the mosfet to see if the circuit is still functional in this new configuration, but this time oscillation did not occur. The circuit can be seen in attachment 'circuit2'. When the bistable is set, the LED is continuously lit and it's not blinking as it should. My question here is what causes this behaviour and is there a way to leave out the mosfet and drive the astable without interfacing?
Thanks for the replies in advance!
During experimenting I ran into the following problems. I built a gated astable from nand gates which is turned on and off by a nand bistable. The circuit can be seen in the attachment called 'circuit1'. As you can see the bistable is interfaced to the astable via an n-channel mosfet. The two diodes make sure that pulse completion occurs when the bistable is flipped during a high astable pulse and therefore the pulse is not shortened. This circuit works as it is supposed, I have tested it on a breadboard. However, I am not sure if the pull-down resistors marked R5, R6 and R11 are needed, if someone could help with this small question, I would greatly appreciate it.
My other problem is that I tried to omit the mosfet to see if the circuit is still functional in this new configuration, but this time oscillation did not occur. The circuit can be seen in attachment 'circuit2'. When the bistable is set, the LED is continuously lit and it's not blinking as it should. My question here is what causes this behaviour and is there a way to leave out the mosfet and drive the astable without interfacing?
Thanks for the replies in advance!
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