Is this driver efficient or not? / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Is this driver efficient or not?

1 2 next

Move Thread

LAN_403

Plasmaarc452

Thu Jul 24 2008, 06:47PM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

I found this simple 555 flyback driver and I was wondering how efficient it is, I am going to radio shack to get the mosfet and capacitor right now to build it but I just want to know about how much power I can get out of it.

Here it is!

Sulaiman

Thu Jul 24 2008, 07:01PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

The IRF510 is only rated for 5.6 A continuous and 20A peak
Rds(on) is about 0.5 Ohms so I don't think it would be either efficient or high power.
The basic circuit is OK so substitute a better power mosfet and it should be ok.

Dr. Dark Current

Thu Jul 24 2008, 07:05PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

The circuit is not very efficient

I think that just nearly any mosfet will heat in this driver unless you make the quasi-resonant mod.

Plasmaarc452

Thu Jul 24 2008, 09:34PM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

I got the parts for this driver, I am building this as a test. If this works I will upgrade to a much higher power mostfet like the IRFP250 or something like that.

Plasmaarc452

Fri Jul 25 2008, 02:13AM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

I just finished the driver and it seems to work very good, the arc is about 1cm to 1.5cm long but the current is very low. I tried charging a 160uf 500v capacitor and it was charging volt by volt which is no where near fast enough to be of use. Well this is my second driver my first driver was the single transistor driver so this is much better in my opinion.

I plan on getting bigger mosfets and separating the 555 timer power +12v from the mosfet power +24v to 48v. I will obviously have to get a few IRFP250's to use instead of the IRF510 but thats no big deal.

Then after I get this up and running I will take a shot at building the ZVS flyback driver!

Antonio

Fri Jul 25 2008, 02:37AM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Charging a 160 uF capacitor to 500 V with 1 mA takes 80 seconds. This circuit may produce a few mA. To increase the current while keeping the same maximum voltage you have to increase the power supply voltage and the switching frequency, in the same proportion.

Plasmaarc452

Fri Jul 25 2008, 03:15AM

Registered Member #1394 Joined: Sun Mar 16 2008, 06:18PM
Location:
Posts: 111

The voltage cannot be higher than 15v on this circuit because the mosfet and 555 operate off the same power. The 555 timer is the problem, the ones I am using cannot exceed 15v without the possibility of damage (18V max). So if I wanted to take the voltage to say 48v I would have to run the 555 timer and the little transistors off a 6-15v power supply and then the mosfet and the primary coil would be connected to the 48v supply.

Kind of like this schematic

My circuit is constructed differently but as you can see the 555 is seperated from the mosfet which is what I will have to do in order to run it at higher voltages.

Dr. SSTC

Fri Jul 25 2008, 06:37AM

Registered Member #1407 Joined: Fri Mar 21 2008, 07:09AM
Location:
Posts: 222

Dr. Kilovolt wrote ...

The circuit is not very efficient

I think that just nearly any mosfet will heat in this driver unless you make the quasi-resonant mod.

i totaly agree jan i think the effiecency gets to like 80% with the mod, in my resonant driver the mosfet doesnt even heat, but the arcs arent as big as Jans either

quicksilver

Fri Jul 25 2008, 02:55PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

In other discussions of the use of 555 chip circuits for a flyback I think some very well thought out points were made: personally I would reserve the use of a 555 oriented circuit for a ignition coil - not a LOPT.
However......I think it's a good idea not to compare apples to oranges. If I am getting a comparison going I want to change only one thing at a time so the arc size, shape, etc means something visually.

But be that as it may..... I have yet to see any of the 555 timers used on a LOPT given 12Vdc 3A exceed that level of energy and the circuit not have difficulties. A simple circuit with one strong switching transistor that was designed to handle inputs of 20+v and 8+ amps will generally knock the doo-doo out of any 555 oriented unit.

The Mazilli driver can handle 40 volts with 10amps for a lengthy period. If the flyback can also (another whole subject) - that arc will look very much like a NST arc at about 3"+ wide consistently. It will not be a tiny blue line stretching the length of fingernail.

Dr. Dark Current

Fri Jul 25 2008, 03:01PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

The "555" flyback driver with my quasi-resonant mod will handle a lot of power, I had it draw more than 5A from 35V (around 200W) with single IRFP250 and it was hand warm on a moderatly sized heatsink. I'm posting the circuit here again in case anyone wants to experiment. I had gotten up to 13cm sparks between 2 stationary nails.

1 2 next

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