Actually, you would be using the high-current-capable MOSFET or BJT as a switch.
When fully switched on, the resistance across the MOSFET's high-power-capable Source and Drain terminals (often called Rdson) might be in the very low milliohms. And THAT means that even with many amps through it, it won't dissipate much power! So it won't get too warm! i.e. It will not be quickly detroyed! So if you hook one of its terminals directly to your power supply and the other one to your load, BAM! You get about the same waveform shape as your 555 output, but it's now controlling almost a "dead short" (switch) directly from your power supply!
One main performance (and reliability) issue, when using a MOSFET as a high-current switch, is that you "must" be able to make the MOSFET not spend too much time _between_ the "off state" and the very-low-resistance "on state", because between those two it has more resistance in the high-current path. And more resistance would mean (much) more "i-squared-times-r" power dissipation, which can get way too hot to touch, very quickly, and can very easily destroy the device.
So, in reality, you have to make sure that you can bang the MOSFET's gate very hard, and very FAST, when turning it on and off. So (and I am not sure whether or not it would always be necessary, when using a 555 to drive a MOSFET), you might even want an intermediate medium-power switching device in between, such as a smaller transistor, to be controlled by your 555 output to drive the MOSFET's gate.
And you would definitely also want to use a MOSFET with a very low gate capacitance, since any capacitance will form an RC "time constant" with the resistance in the circuit (and there always is resistance, even with no resistors), slowing down the turn-on and turn-off times, which is bad (for already-mentioned reasons).
With such high-speed edges (you hope), you also need to pay attention to trying not to allow the formation of high-frequency "ringing", i.e. damped oscillations, especially in your gate voltage, since the higher frequencies have more energy and can tend to heat up the MOSFET, and also might incite actual sustained HF oscillation, which is much worse and more-quickly destructive.
Cheers,
Tom
positive feed back may increase the bandwidth!What is The maximum Freq. Of 555 Ic ....?
In image you can see the schematic, Pls. see as they are connected not by terminal but by using net name.There is no schematic of your circuit and there is no explanation of what the waveforms are for.
Hi, what is this arduino.arduino (PWM signal)
Man, stop being a retard and use the damned GOOGLE!Hi, what is this arduino?
I dont know where you connected the capacitor,its not in the circuit diagram you posted but one thing you should note that capacitors offers resistance to any AC signal ,its called reactance.So be sure that the caps value is proper for the frequency its working on.But, when I tried to connect a non polarised (0.47 μf) capacitor the cfl does not light at all. Also the capacitor does not charge when connected to the output. Why is it so? Is it because of very low the output current?
RRITESH KAKKAR said:
How far is the END...!!
by Jake Hertz
by Jake Hertz
by Jake Hertz