555 trigger circuit

[robert miller]

Trying to hook a receiver to my mono 555 circuit and i will not drop the voltage to trigger. the timer. Any ideas on how to drop the voltage on pin 2 from a electronic grounding pulse that will start the timer?

 

[George]

Not sure I know exactly what you are looking for but maybe try using an electrolytic cap.

 

[robert miller]

George: I tried a cap and that did not work because there are no AC type signals involved with this circuit. The wireless receiver has a 1K circuit resistance that drops to 0 ohms when triggered. When hooked to the 555 at pin 2, the circuit pulls the voltage on pin 2 below trigger point and will stay on till pin 2 is disconnected and just a wire in the air. Touch this wire to ground and the 555 works perfect. I will be trying to add NPN xsister between pin 2 and the receiver to see if this will couple the two circuits. Will post the results later to day. Thanks for reply

 

[George]

The cap should work for single trigger even though its dc. I know dc does not pass through caps but they work in this case. I will send a tested schematic in the morning after I get home from work.

 

[George]

Use your NPN and cap. Fleck showed me that.

 

[robert miller]

George: I tried the cap and also using NPN. Unfortunately neither helped. I am going to try using a 741 opp amp to see if this will work. I believe that my very small voltage gain from the receiver will make the opp amp flip and trigger the 555. thats my guess and iam sticking with it. Will post the out come.

 

[robert miller]

Just realized its april fools day. got to prank some one today. or get pranked? My spelling is a joke.