Boost Converter Help

Thread Starter

ItsTheFark

Joined Jun 14, 2009
24
I am new to the world of electronics and creating circuits etc. etc. and I wanted to make this Boost Converter off this website http://www.anothercoilgunsite.com/nf-portable-construction.htm

I have been having trouble understanding what half the symbols mean, for example:

The resistor symbol with the arrow going through it

The single black rectangle that says +12V next to it

The non-regular pentagon on its side that says V_Switch

The grounded symbols off of it... does that just mean a loose wire?

The larger circle with the + and - in it

I know this is a big request but any help is appreciated, because as i said, im new to this but i have a desire to learn it.
 

DrNick

Joined Dec 13, 2006
110
Most of the symbols you are confused about are NET labels. They are just names for certain wires in the circuit.

The resistor with an arrow thru it is a potentiometer. It is a resistor that you can change by moving a mechanical wiper by means of a dial that you spin.

The large circle with the + - in it is just a voltage source.
 

DrNick

Joined Dec 13, 2006
110
After looking at this circuit a bit further, I have found it to be pretty crummy. It is an open loop boost converter...therefore the voltage at the output can be made obscenely high depending on how you set the duty cycle of the 555 timer (using the potentiometers. It would be better to use some sort of zener clamped charge pump with a bank of capacitors to discharge when you fire the gun...or whatever it is you're trying to build.

This may be an "unsafe" project for you to attempt if you hare having trouble reading net labels...
 

Thread Starter

ItsTheFark

Joined Jun 14, 2009
24
Safety is not the issue... With several family members being electricians safety is the one thing i actually know.

Zener.. pump... wha? Sorry that just blew right over my head.

Before i actually went into this i was going to just use some 9 volt batteries set up parallel, DC/AC transofrmer, AC/DC voltage tripler into the capacitor bank.
 

DrNick

Joined Dec 13, 2006
110
using a low voltage inverter, and a voltage trippler may be better for you, as the high voltage side will be isolated from all of the low voltage circuitry. In the boost converter the switch that is being driven by the 555 timer (which is a crummy way to do it by the way) has 200+ volts at its collector. SO if there is a failure, transient high voltage will be everywhere on your board = bad news.
 

Thread Starter

ItsTheFark

Joined Jun 14, 2009
24
using a low voltage inverter, and a voltage trippler may be better for you, as the high voltage side will be isolated from all of the low voltage circuitry. In the boost converter the switch that is being driven by the 555 timer (which is a crummy way to do it by the way) has 200+ volts at its collector. SO if there is a failure, transient high voltage will be everywhere on your board = bad news.
So basically your saying that my idea is better than a boost converter because it would isolate the high voltage to just the capacitors? Also i looked at that site, thanks it cleared some stuff up.

And lets say i decide to do my origional plan with the DC-> AC converter, and voltage tripler...
A) How will i know when its done charging
B) Will it even stop charging?
C) Could i get an estimation of how long it would take using a 9 volt battery, using the voltage tripler, and fully charge 1 1200uF 450V capacitor?
 
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Thread Starter

ItsTheFark

Joined Jun 14, 2009
24
Would i be able to put an LED somewhere in the circuit to have it go on when it is done charging? And how fast would it charge?
 
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