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Boost Converter help Answered

I need a dc-dc boost converter that will step 25.9 volts at 2600 mah up to around 388v at 360 ma will I need a battery back with a greater amp output I can get up to 12000 mah at the same voltage any suggestions I am trying to charge a .1 farad cap bank that consists of only 10 caps

Any help is appreciated -TDC



3 years ago

Supply= 67.3W (at rated levels), output =139.68W...

If we could work like that it means you have to draw around 5amps during the charging.

For an inverter that can handle this you are looking at some serious transformers, even at high frequencies.

At those power levels it is often easier to charge directly with rectified maind power - using a current limiter of course and for lower mains power a voltage doubler first.

Building an inverter to run from batteries is certainly possible but requires decent knowledge of the converter technology, some quite expensive parts and most likely a lot of frustration until you got it right.

For big cap banks it often pays off to charge the caps as singles instead of charging them all at once, depends on how fast the cap can be charged without problems and how much time you can waste charging.

Also keep in mind that one little mishap can mean fire, destruction and even death when playing at those power levels.

A much simpler approch is the circuit of flash cameras, the disposable ones.

Schematics for most types are available and all you need is to adjust the voltages to your input and to use a suitable (hand made) transformer at the output.

As you need high efficient and high power transistors for this you might want to seek other options unless you are quite good with inverter technology...

I plan to charge them in sets of 2, As well you are saying I am better off building the transformer myself?

You won't find a suitable tranformer for cheap on the scrap.

Same for the electronics protecting the caps and charger.

It is not really hard to re-wire a transformer for other voltages than intended.

Just get the no.load voltage close to what the caps need and add a current limitig resistor as the most basic charger.

Involves a bit of trial and error or a lot of calculations and searching through datasheets but well well worth it if you are on a budget.

With your voltage needs you might even get away with a used photo flash unit for mains power use - you know the kind profissional photo studios use as sencondary flashes.

Also strobe lights work at similar voltages and can be substituted as chargers as well.

All depends on how fast you have to (or can) charge the capacitors...

I need a minimal 30 sec charge but I will take your advice about the microwave transformer. I am very confident with the power supply that I ordered recently can handle the job I just need to up the voltage. Thanks for the help.

With a fast charge like that do yourself a favour and monitor the temp of the caps!

Energy has to go somewhere and usually this goes along with a lot of heat.

The last thing you want is a big electrolytic cap to explode inside your home - trust me!

Been there, done that and it is a damn mess to clean up.

And although you certainly want max output power consider a suitable resistor on the output to prevent a dead short on the caps, they will thank you with much longer lifetime and good performance.