A few questions about uzzor's boost converter / Electromagnetic Projectile Accelerators / Forums

Forums

4hv.org :: Forums :: Electromagnetic Projectile Accelerators

« Previous topic | Next topic »

A few questions about uzzor's boost converter

Move Thread

LAN_403

jnbrex

Wed Jun 15 2011, 01:06AM

Registered Member #3950 Joined: Wed Jun 15 2011, 12:45AM
Location:
Posts: 51

I have recently received the parts to build uzzor's boost converter, and have a few questions. This will be my first circuit assembly ever, so please bear with me.

1. On the LM311, I know that pin 7 is the output, pin 2 is the positive input, and pin 3 is the negative input. By researching I have come to the conclusion that pin 8 goes to the positive battery terminal, and that pins 1 and 4 are grounded. Is that true? If it is something different please correct me.

2. What can be used as a ground?

3. The positive battery terminal is located at the top of the circuit, but the negative is not marked. I have come to the conclusion that the negative terminal is located just before the ground, is that correct?

4. I designed a stripboard schematic, but I am sure it wastes tons of space and uses many wires for connections. Does anyone have a stripboard schematic for the boost converter?

is the schematic of the boost converter.
Thank you!

currentkills91

Wed Jun 15 2011, 01:31AM

Registered Member #3831 Joined: Thu Apr 14 2011, 02:54PM
Location:
Posts: 265

1-Yes that is all correct.

2-The ground is just going to be the negative terminal of your battery.

3-The negative is actually marked, it's the little symbol hanging off the bottom of everything, so yeah that's correct.

4-I can't help you with this one sadly, just try and lay it out neatly and get it to work first, if this is your first project.

Good luck with it (:

coldcity

Wed Jun 15 2011, 01:35AM

Registered Member #1406 Joined: Thu Mar 20 2008, 12:12PM
Location: Deepest darkest Wales, UK
Posts: 27

Hi -- I'll take a stab as I'm about to build it myself :)

1. Yep, spot on.

2. It's a slightly misleading term when you're thinking in terms of battery circuits that aren't connected to a ground! In this context it's simply a common connection point that goes to 0v (the negative battery terminal). In the circuit diagram you linked to, everything connected to the top line goes to positive as indicated, and the ground symbol just signifies that everything connected to that bottom line is connected to 0v. So pick a track on your stripboard layout, and call it "ground" :)

3. Negative batt connected straight to ground as above.

4. If you want a really small one, you could try and reverse-engineer the stripboard layout from the photo at the bottom of Uzzors' page!

I'll possibly do a layout when I build mine -- I usually build ham-style, "dead bug" on a piece of unetched single-sided PCB, but the fact most of the circuit is those two chips means I might try and find a piece of stripboard in the junk box :)

coldcity

Wed Jun 15 2011, 01:36AM

Registered Member #1406 Joined: Thu Mar 20 2008, 12:12PM
Location: Deepest darkest Wales, UK
Posts: 27

Whoops, sorry currentkills.

currentkills91

Wed Jun 15 2011, 09:33AM

Registered Member #3831 Joined: Thu Apr 14 2011, 02:54PM
Location:
Posts: 265

Haha, ya gave more in depth answers then I did anyway :p

jnbrex

Wed Jun 22 2011, 10:28PM

Registered Member #3950 Joined: Wed Jun 15 2011, 12:45AM
Location:
Posts: 51

So, I finished the circuit today. Unfortunately whenever i use it, it charges to 3-4 volts... then stops. I've measured the input power as 12.5v, so I'm using enough power. I tested every connection and they're all good, so I have no idea what is causing the circuit not to work.
Does anyone have any idea what could cause the circuit to only charge to 4 volts? That could probably identify the problem.

Saz43

Wed Jun 22 2011, 11:42PM

Registered Member #1525 Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294

Something is definitely not right. Check your layout again. If you look at the schematic, your battery should be connected to the capacitor bank through the inductor and output diode. Even if the boost wasn't working, the capacitor bank will charge to at least battery voltage if everything is connected right.

jnbrex

Thu Jun 23 2011, 12:12AM

Registered Member #3950 Joined: Wed Jun 15 2011, 12:45AM
Location:
Posts: 51

Well I think I may have found the problem... I tried again numerous times, and it charged to 11 volts once. Eventually I started to smell something smoky in the air, and found that the MOSFET was extremely hot! I quickly turned off the circuit, grabbed a piece of aluminum heatsink, and pressed it to the MOSFET. My conclusion is that the diode is faulty, and failed, letting the current from the inductor avalanche into the MOSFET. I'm waiting for everything to cool down, and praying that the MOSFET isn't completely destroyed.

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob