How can you make anything without looking at the datasheet???nikhil arora said:
I donot know whether it is Rf choke but it is like a 1/2W resistor with color band markings.try a bigger inductor, and make sure it's a power inductor, and not an RF choke
i am using IRF540 and a 2200uF electrolytic capcitor.the only 'critical' parts I've run into on these things, is (A) the switch itself and (B) the output capacitor ... you're probably right about the ESR of your 2200uF cap being too high
its Rsc resistor for current limmiting lesser it is more current u can draw before ic shutdowns it self.also, it could be your piece of wire for the osc resistor has the clock running too fast, and the switch and/or diode can't handle it?
the input is from battery 6V,4.2Ah and i have connected 1000uF at input.also, where is the 6v coming from ... do you have sufficient input capacitance?
That's a RF choke, completely unsuitable for you purpose!.nikhil arora said:
Like Nigel has said, this is an rf choke ... a "power inductor" is usually wound on a torrid or bobbin core, and is larger than an rf choke ... here are some pictures (mainly surface mount) http://images.google.com/images?q=power+inductor ... you can see a power inductor I wound myself in this picture ... it's the green torrid with white wire wrapped around itnikhil arora said:I donot know whether it is Rf choke but it is like a 1/2W resistor with color band markings. I donot know it power handling capacity.
The IRF540 is a high voltage medium current transistor, rated for between 80 to 100 volts ... and as such, requires substantial gate drive Vgs of at least 20v ... most likely your smps controller is not able to drive the switch fully on. You need a "logic level" mosfet, something with a much lowr Vgs requirement ... IRLR, IRLU, IRL, etc... these are all logic level parts compatible transistors, and don't take 20 volts on the gate, instead they generally take under 10, some as low as 1.8i am using IRF540 and a 2200uF electrolytic capcitor.
that sounds fine, again, use smaller caps in larger numbers, try something like four 100uf in parallelthe input is from battery 6V,4.2Ah and i have connected 1000uF at input.
if you have any dead computers laying around, or anything that would have a power supply in it, you could harvest inductors from them.nikhil arora said:how the inductor for dc/dc look like
I have few more inductors
so which type of inductor should I use