I want an opinion on this boost converter 5 volt to 50 volt

[alexaamnda]

Is this circle worth developing, knowing that I am a beginner?

 

[BradtheRad]

The led's themselves can do the same job as D1, so there's a chance you can replace D1 with a straight wire and eliminate the output (reservoir) capacitor(s). Then the led's flash brightly and briefly once per cycle.

The two-transistor method needs a certain amount of experimentation, in order to get ample power throughput. Can you tally how much current your led's require? The 5V supply must provide greater bursts of current.

 

[dick_freebird]

Simple boost converters are not as efficient at high step-up ratios. This is usually a key interest. You might be better off with less ratio and lower stack on the lamps. Tall strings are for equal current, equal light per emitter as freebie without requiring opto device fine matching.

Appears to be a self-oscillating scheme that fails to sustain. Getting oscillators to start is a simulator jockey challenge. Even if otherwise functionall.

String current is the care-about for LED illumination but feedback appears to be nil, or output voltage returned to the oscillating loop, a sloppy proxy at best.

Big FET and little one legged driver begs failure. Or maybe the fat FET is the timing C of the whole thing (if it worked). Expect FET switching to be very wasteful at best.

 

[alexaamnda]

The led's themselves can do the same job as D1, so there's a chance you can replace D1 with a straight wire and eliminate the output (reservoir) capacitor(s). Then the led's flash brightly and briefly once per cycle.

The two-transistor method needs a certain amount of experimentation, in order to get ample power throughput. Can you tally how much current your led's require? The 5V supply must provide greater bursts of current.

Hello, thank you, brother, for your response. Is there a way for me to contact you? Thank you. I am a beginner in this field.

 

[alexaamnda]

Simple boost converters are not as efficient at high step-up ratios. This is usually a key interest. You might be better off with less ratio and lower stack on the lamps. Tall strings are for equal current, equal light per emitter as freebie without requiring opto device fine matching.

Appears to be a self-oscillating scheme that fails to sustain. Getting oscillators to start is a simulator jockey challenge. Even if otherwise functionall.

String current is the care-about for LED illumination but feedback appears to be nil, or output voltage returned to the oscillating loop, a sloppy proxy at best.

Big FET and little one legged driver begs failure. Or maybe the fat FET is the timing C of the whole thing (if it worked). Expect FET switching to be very wasteful at best.

Can you help me, brother, to modify this circuit?

 

[Easy peasy]

have you looked at the peak currents in all the major power parts ?

for 5V to 50V a cascaded booster ( i.e. two of ) running at 20kHz from a control IC would be a safer choice

 

[BradtheRad]

Certainly other members can assist with this circuit (and boost converters as a topic) than I. By building it you'll encounter hurdles yet it's all part of the territory. It's better (and the purpose of this forum) if you present your questions in this public fashion so that any and all readers can reply. Also so that future readers can read and benefit.

You may also discover other boost converters to experiment with. The essential ingredient is a fast-operating snap-action switching system. You may even find that a logic gate is sufficient as the essential ingredient to build a boost converter. A beefy transistor helps a lot when you wish to power so many bright white led's, of course.

 

[KlausST]

My personal opinion:

I would not build this with discrete parts. .. and fumble around to make it work.
I´d rather use a dedicated LED driver IC. There should be selection tools to find the most suitable one.

Klaus

 

[scopeprobe]

Parallel chains of LEDs will likely not be balanced due to the variable Vf of the LED. You would likely want to include a small resistor in each chaiin.

 

[alexaamnda]

My personal opinion:

I would not build this with discrete parts. .. and fumble around to make it work.
I´d rather use a dedicated LED driver IC. There should be selection tools to find the most suitable one.

Klaus

Yes, I am trying to modify this circle. It is still in its early stages, my brother.

 

[alexaamnda]

Parallel chains of LEDs will likely not be balanced due to the variable Vf of the LED. You would likely want to include a small resistor in each chaiin.

Yes, brother, this is what will happen, but I am talking about the circle in general and I want to develop it.

 

[BradtheRad]

The inductor's Henry value is not critical. It can be much less but its flux field has to build and collapse sufficiently that it powers the load. That is to say the core must be able to store sufficient Amperes short of reaching saturation. When it saturates it cannot give back the entire amount of power placed in it.

I played with many simulations of a similar 2-transistor boost converter. And built it in hardware. These are mostly low power and low voltage. The transistor arrangement is a sziklai pair which can work although all component values must be experimented with. To start out a load of a few hundred ohms is adequate. Then try 2 or 3 bright white led's in series.

A load must be connected all the time your boost converter runs. Without a load, voltages can build quickly to alarming and destructive levels.

 

[dick_freebird]

Designing in a backstop open-drain clamp may save you some grief. Or maybe an avalanche rated FET, no higher BV than necessary, and let it. Unclamped inductive switching is the operating principle. Too much output voltage compliance however does not help and more adds hazard as others note

There are plenty more forgiving ways to chattér a FET gate but (and because) they are integrated circuits; simple but still. A CD4000 phase shift oscillator and parallel emitter ballasted NPNs could work from 3 to 15+ volts (if you can find the good ones anymore).

OP, are you committed to this particular bodge? And if so why? From other comments this one seems like a lot of bench time to get working with some ability to cause damage. You sure this one is for you?