If it is 10x a month you don't need to change batteries.Calculation can be ok but components not, capacitors not always have the value as is it say on it, increase R1.Leave MOSFET as is, just connect everything and observe what is happends.When you make a drawing dont use description - Pin1, just 1, thats what is in practice, ehen you describe something in text, use Pin1
What I am learning is to use N-Channel if between load and ground and P-Channel if between positive and load. So the N-channel could have worked if drain was connected to ground? Correct?For decoupling of the 555, does that mean a capacitor between drain and ground? It's C3 in the diagram but I don't know to calculate it's capacitance. How do you recommend switching/powering the LED? Do I still need a MOFSET as Ted recommended? And I am guessing it should be a P-channel if so?Think I should look into MOSFETS with a lower Vg(th) (currently 2V) and a 555 IC with lower operating voltage (maybe LCM555 or TLC555)? I'd like to power this thing with the minimum number of AA batteries. Right now I will need 2V (Vgth) + 4.5V (555)
:-Without the MOFSET, the LED blink frequency would increase with time = overloaded 555, frequency is changing because LED resistance is decreasing-With the MOFSET, the blink frequency appeared to stay constant = MOSFET is controlled by voltage , does not take a current from 555-The brightness of the LED decreased with time for both cases = look at the link, you need low voltage MOSFET-There overall brightness of the LED was less when using the second MOFSET compared to not using it = LED is taking power (current) from 555 not directly from battery. So what I have learned is that there is a voltage drop across a MOSFET and that drop is equal to Vg(th) = MOSFET is not completely open, low voltage MOSFET is need.. I am going to look for lower Vg(th) MOSFETs and lower voltage 555s. = first yes, second no
Correct.A capacitor across the supply of the 555 (pin8 and pin1).100uF with at least a rating of max battery voltage will do.The LED can be switched with an n-channel mosfet, regardless how you're switching the power to the 555.But all the diagrams seem to be wrong there as well.Source to NE555 ground, gate to NE555 output (with or without 1k resistor),and LED (with suitable current limiting resistor) between NE555 supply(+) and drain.Battery voltage needed depends mostly on Vf of the LED(s).White power LEDs have a Vf of ~3.3volt, red ~2.4volt.Add at least a volt for the LED CL resistor and mosfet(s) losses.A Cmos 555 (ICM7555 etc.) works reliably from 2volt, a common NE555/LM555 needs at least 4.5volt.A mosfet with a Vgs(th) of 2volt needs at least ~3.3volt.Up to you do do the rest of the maths.Leo..
Watch the video, this guy achieved what you need @ 12v =increase your voltage or look for another MOSFEThttps://www.elcircuit.com/2017/07/mosfet-timer-circuit-simple-and-easy-to.htmlthe problem is in first MOSFET, short D and S of it, and make working LED.
Just Google "fet symbols" (images) to confuse you more. There are many.Just go by Source/Drain/Gate.The diagram in post#36 seems correct (assuming you have the timing of the 555 right), but I think it's better to move the LED supply (R5) from the 555 supply to the battery.Then you have more LED power (LED current through one fet only), and you can use a smaller p-channel fet between battery and 555.Leo..
TLE7272-2 Here is your solution - voltage regulator with EN pin, attach to it R1C1 and you done.https://www.google.ca/search?q=TLE7272-2&rlz=1C1AFAB_enCA475&source=lnms&tbm=isch&sa=X&ved=0ahUKEwif7uSu1IPaAhUG6YMKHTsNAVQQ_AUIDCgD&biw=1440&bih=787#imgrc=Vp2FaHNMYtjDYM:Watch video again min; 8:00 to 9:07. One min. timer with 3 sec dimming effect.
Hi,I just saw this thread and have not followed it from the beginning. However a note if you are still planning on using the 555 timer. Look for a 555C which is a CMOS version of the 555 timer and much more battery friendly.
Already mentioned a Cmos 555 in post#31.Current draw of the 555 is irrelevant here, since the 555 is switched off with a mosfet most of the time.Leo..