Problem with simple bistable 555 circuit

[rsi77]

Hello All,

I just bought a simple circuit design software (TINA basic) and drew a simple 555 circuit which I want to use for a new project. The first circuit I made (bistable) is supposed to lock the output in the high/low position if you temporarily touch Trigger/Reset to ground. I try testing the circuit with a virtual Multimeter and it doesn't lock at all--the output stays in the low position unless I'm touching the trigger to ground (push momentary 1 in attached diagram). As soon as I let the trigger go high (stop pushing momentary 1) the output (pin3) goes to back to low position.

I thought the software must be wrong, so I made the same circuit on a breadboard and it does exactly the same thing!

Am I missing something? This seems like it should be very easy.

Any thoughts?

Thank you very much.

 

[ericgibbs]

hi,
Try it with the THRES pin not connected.

E

 

[rsi77]

Well I found a problem with my breadboard circuit--Pin 1 of the 555 wasn't grounded. Now it works both with pin 6 grounded or not grounded.


Thanks for the reply.

I'm still not sure why my virtual circuit doesn't work--but I guess that's a question for the software makers, not real-live circuit builders.