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What transistor should I get?

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Plasmaarc452

Mon Jul 21 2008, 01:08AM

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

This is just a really quick question, I have made the single transistor flyback driver many times before but I cannot seem to find a good transistor.

The 2n3055 is a piece of crap, it charges very slowly and gets really hot.

The MJE13009G is also a piece of crap, it charges slowly and if I take it above 6v input it frys even with a heat sink and fan.

So is there any REALLY beefy transistors out there that can take 24v - 36v?????? At say 5 - 10 amps???????

...

Mon Jul 21 2008, 02:08AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

have you considered changing driver designs instead of transistors? The mazzilli driver is easy and way more efficient that the 2n3055 drivers...

Plasmaarc452

Mon Jul 21 2008, 02:53AM

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

Yes I have considered this I just think that when I build it the whole thing won't work.

I am willing to try it, I just need to get the right parts read my other post.

Dr. SSTC

Mon Jul 21 2008, 03:30AM

Registered Member #1407 Joined: Fri Mar 21 2008, 07:09AM
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why do people even bother with the single transistor design its just a thing that you play with onece and hopefully go on and build a better driver

Plasmaarc452

Mon Jul 21 2008, 05:10AM

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

Alright, I am going to build the ZVS driver. I got my parts list correct and as long as I heat sink it and put it together correctly it should work!

Screw this single transistor design, no matter what Transistor I use its gona fry.

Dr. Dark Current

Mon Jul 21 2008, 06:24AM

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

Before you "tear it apart" you could try

But of course you will get 10 times more performance from a zvs driver.

aonomus

Mon Jul 21 2008, 06:34AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

Forgive my ignorance, but 'charges slowly'? I bought 4 of the MJE13009s from digikey and they're my next transistors to use as a step up from the 2n3055. What kind of heatsink and thermal interface material did you use?

quicksilver

Mon Jul 21 2008, 02:59PM

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

jovica93 wrote ...

why do people even bother with the single transistor design its just a thing that you play with onece and hopefully go on and build a better driver

This is a very interesting idea! I had often thought of using two transistors: even two 3055's and comparing them to a single.
But realistically one of the thing I like about this design :

- is that it is really simple and with the MJE15003 (in TO-3) happened to be the most robust I have ever used as a single (250Watts!). transistor design. IF you want a simple very flexible design; that is a darn good one. I have used the MJE13009 with a well made heat sink (for the TO-220, it's my opinion that since the size of the unit is smaller the heat concentrates in a smaller spot and needs to be defused faster to a wider area. The use of a broad, wide heat sink appears to cool it more effectively that a thicker one) and gotten very fine preforming from it. But it take a balance of just slightly differing resistors. For me, I used a 470 & 25. One other issue is that there is a difference between several brands of what is sold as MJE13009. I have used a Fairchild and it was fantastic! I also had one I pulled from a pre-existing item (different brand name) and it simply wasn't the same quality!

I found that MJE13009's could be bought at 89 cents a unit but the 2N3773's or the MJ15009's were very expensive. TO-3 designs are just large & expensive! The heat sinks needed raise the cost substantially. However, from a single transistor design as per the above the MJ15009 was the best I had ever used for given returns in arc size return for a given voltage, current handling and cool operation.
I spent a great deal of time getting the Mazilli driver to a compact size in a completed form using a pref-board and it's not an easy design to reduce in size. Realistically, it's the center tap of the primary that creates more complications (IMO) when using that style of driver, as there are just so many flybacks with the room available to do it justice......

I have experimented with the Mazilli driver and the issue I confront is the center tap of the primary. Some flybacks just don't have the room to do justice to the concept. Also, when comparing transistors, note that some are designed to handle more current, some more voltage. If you are going to raise one or the other, adjust the components appropriately. The MJE13009 is made for a higher level of voltage, while the heavier TO-3 designs (listed above) seem to be designed to handle higher current levels.

Plasmaarc452

Thu Jul 24 2008, 07:08AM

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

I only have 2 MJE13009G transistors left that are new in the package but I have 2 more that I took off some of my old circuits that I believe work. I will try and get these working better but I think I know why it charged so slow. I did not wrap my own coils, I used the internal primary's which may have caused some problems. I will try to wrap my own coils but we shall see what the outcome is!

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