sir,
I carried out certain experiment with ac 12v to 30v normal transformer . in the experiment i used load as led. Now the results which i obtained is classfied at this stage, based on the result i am compelled to ask wether is there any concept of dominating cycle when it comes to AC field as one exists in transformer
C=dq/dv, variation of charge with variation of voltage, would present in A.C, but as the voltage is low, the effect could be neglected. The inductive effect L= do/di, variation of flux(A.C field) with variation of current(load), should be considerable and should be considered. The circuit offered reactance would, Xl=2(pai)fL, and would be more with rise in frequency.
Transformer outputs should always be symmetrical. If you are using an LED as a load, the current will only flow in one direction and the voltage across the LED in the conducting direction will be lower than in the non-conducting direction. I'm guessing a setup like in the picture. Unless your transformer has a high internal resistance, you'll need that current limiting resistor to keep your LED from burning. Are your results a voltage or current measurement? On a scope or multimeter? How are you driving the primary of the transformer? Line voltage and frequency?
sir
suppose i have a step down transformer with rating 1hz 12volt connected to led acting as a load, so in this case how my led would behave in terms of emitting light for incomming positive and negative cycle
Forward bias, would be for half cycle when current would flowed,and reverse bias, for other half when current would not flowed, yet led would emit the light, as like constant light, as frequency is 1.0 Hz/sec.
Sir can you elaborate bit more on the last line of the answer provided by you
Lot of thanx sir
Driving a single LED with a transformer could result in some asymmetries from your transformer that will be core and frequency dependent. It's doubtful that you would see any effect from this at 1Hz. What Bhupendra is saying, is that your LED will be conducting (and therefore emitting light) for only one half of the AC cycle while it is forward biased. During the other half of the cycle, it will be reverse biased and not conducting ( therefore no light is emitted). The result at 1 cycle per second is that your LED lights for 0.5 seconds and then is dark for 0.5 seconds. If you run at line frequency (50-60Hz) you may not notice the flashing but the current will still be interrupted while the LED is reverse biased. Remember, an LED is a Light Emitting Diode, it is therefore behaving firstly as a diode. The light emitting part is a result of the current flow when it is forward biased. There is also little to no current flow when the LED is biased below the forward bias voltage which is typically around 1.2 to 2.4V depending on the type of LED.
Frequency is 1Hz.,hence T=1/f = 1sec, hence it would appeared as constantly glowing......though off for half cycle, in every cycle.
Sir
with regard to just above answer i am attaching my following observations kindly go through it a big favour sir
I already said T=L/R, the circuit time constant should be considered....
EXACTLY SIR THANX FOR SHOWING ME RIGHT PATH THIS WILL HELP ME IN MY STUDY SIR AAPNE UNKNOWINGLY SHOWED ME A WAY OUT
- Badges
- Science topic
- Similar topics
- Engineering
- Control Theory
- Control Systems
- Control Systems Engineering