Did you look at the schematic? Trace Pin2 to Q22/Pin3. It should make some sense to yourself by now.
Did you means that pin 2 and 3 are connected ?
Did you look at the schematic? Trace Pin2 to Q22/Pin3. It should make some sense to yourself by now.
See picture. Pin 3 Low output means the internal transistor shorting pin 3 to ground. Thus pin 3 shorting to ground completed the circuit of LED and turns on.
Follow the current flow path from + side of 4.5V battery flow thru LED and R1 to pin 3 , internal transistor of ne555, ground then last to - side of 4.5 battery.
Can you please show me your diagram referring to the flip flop.
Hi vick5821,
I suggest that concentrate learning electronics by its symbol or block diagram. Just remember its inputs, control ,output and function of IC or circuit. It's easier to learn electronics this way. Then slowly learn simple transistor circuits. I'm sure you can you can interpret or analyse the internal schematic diagram of ic components in the future.
So, so far I just need to roughly know the external function of the pins can already ? ignore the internal working principle ?
Yes. Try this link. Waveform was included. It might easier for you to understand.
http://www.kpsec.freeuk.com/555timer.htm
I am with Rleo, this thread has only got way more confusing then it ever needed to be. As someone who is starting out you should not be trying to understand the intricacies of an IC circuit. Instead you should just be understanding them enough to put them to use in other simpler circuits. That is why they created IC's, so us not so brilliant hobbyist have the ability to make cool things without all the bs. Even then it is hard enough!!
vick5821,
One more advice.
Learn Ohm's Law. This will help you a lot in analyzing circuits. Most electronic formula was derived from Ohm's Law.
@vick5821
Nice work. Good idea for the 2nd picture. Placing socket pins for solder less component.
the 555 timer consist of comparators that compare the voltages at the trigger pin and at the threshold pin................in fact, d 555 timer got its name from the three 5-kilohm resistors that set these voltages..............
anyway, lets take the astable configuration first:
NOTE: high = supply voltage and low = 0V)
ALSO NOTE: "active high" means that the pin only functions when the pin is connected to the positive supply rail..........."active low" means that the pin only functions when the pin is connected to ground
the circuit starts with the capacitor uncharged (at 0V)..........
1. when the circuit is switched on, the capacitor immediately starts to charge, increasing in voltage gradually.....the speed of charge is determined by the resistor values and the capacitor value.....the capacitor charges because the trigger pin is low (at least lower than 1/3 of the supply voltage)........the output pin goes high (becomes
2. when the the threshold pin detects that the voltage at the capacitor is greater than two thirds of the supply voltage (2/3 Vs), the output pin goes low (becomes 0V) and the discharge pin also goes low so as to discharge the capacitor............only one of the resistors is involved in the discharge
3. when the trigger pin detects that the voltage at the capacitor is less than one third of the supply voltage (1/3 Vs), the output pin goes high (becomes Vs) and the discharge pin closes (goes high) so that the capacitor can charge once again.........
o yeah, the reset pin is not used in this configuration..............but could be if needed............it just used to "turn off" the ic (make it to stop producing pulses), no matter the input..................i.e. no matter the state of the threshold or the trigger pin, the output pin will not respond............it will remain low (at 0V)..........this happens when the reset pin is connected to ground or is made lower than 0.7V...........
you should be able to use these principles to understand how the other configurations work (but if you don't, just post your questions............i'll answer the ones i can )
NOTE: "active high" means that the pin only functions when the pin is connected to the positive supply rail..........."active low" means that the pin only functions when the pin is connected to ground