Got brain freeze tis morn.
I have seen this circuit and simulated in LT SPICE but just can't duplicate.
the transistor is supposed to stay on for 10 seconds.
I don't think I have the right combo or right component layout
yes well aware that its a very basic circuit but can't think straight today??
this got e bugged last night.
have seen this circuit on the web but?
perhaps the base resistor connected directly to base to limit cap discharge.
presently the led stays on same as pulse.
I am just expereminting with different configs.
It bothers me that I can't locate the web site that had similar but using a relay instead of LED.
had resistor/capacitior combo to turn on transistor for 10 seconds.
Added resistor to emter, increased cap and base resistor but not what I recall on web site that I can't locate.
I am just curious as I know I saw a website that had the cap and resistor in parallel connected to a transistor.
going on a mission to locate that site. it bugs me I can't find it.
QUESTION = where did you get the relay for LT spice?
The chematic as it is will alow the cap voltage to reach (values is just plausible guess) 0.75v while cap voltage is 0.55V when it cease to conduct. Also the base current for a given voltage value is almost impossible to calculate accurate because transistors (even same type) have different characteristcs.
Use a Schmitt triggered inverter, without the schimit trigger you're going to struggle avoiding the linear region of the transistor. Schmit triggers can EASILY be setup to produce one shot values based on an RC time constant with feedback.