Transistor 2n3055

[CitizenDC]

Hi Guys,

Thought I'd relate this for anyone experiencing poor results with bedini type experiments and 2n3055 NPN transistors.

My initial bedini circuits all used ST (manufacturer name) 2N3055 transistors. They where not what I considered cheap, but they worked well.

In an attempt to reduce the costs, I purchased 10x 2n3055 of a cheaper brand(will get the brand name) with a big surprise. These cheaper transistors performed very poorly in my opinion allowing around 30% of the current to flow through the circuit when compared to the ST transistors.

For example, one SSG I tested drew 110ma at 12v running an ST transistor. After switching it with one of the cheaper transistors it would only draw 40ma and the neon would not glow. I had to double the voltage to achieve a similar resulsts to the ST transistor.

After looking around the net for a bit it would appear the ST's specs are far higher than the requirement set for the 2n3055 standard. I'll have to attribute it to that for now.


cheers

[BinzerBob]

One thing that I have noticed with my motor, is that it has two or three stable operating states. For instance i can get it to operate at say

Supply Bat ma Charge Battery ma Motor RPM (approx)
220 approx 60 approx 3600
220 approx 60 approx 2000
etc


When I start the motor I have to increase the resistance on the pot very slowly to get the motor to go to 3600. Also when it is at 3600 rpm if I increase the resistance on the pot just a bit, Ampre jumps and then the motor settles down to the new RPM of about 2000.

Just my 2 cents.. I agree about the transistors as well. they seem to get much criticism from what I read so far. Just a slight change in the transistor charactisitic is enough to set a new operating point.

[Sephiroth]

Interesting... I am also using ST's 2N3055 transistors (until I got my MJ21194 but I've only got one of those left now! ) and their performance seems very similar to the MJ21194 but they fry out alot easier... with the MJ21194s I don't have to worry about the neon so I leave it out to experiment with the full force of the spikes and they hold up fine under normal conditions.

But the 2N3055s (although they perform almost as well as the MJ21194s as far as I can tell) will fry INSTANTLY if there is no neon or load present.

[theremart]

RE: transistors..

Ahh the fresh smell of cooked transistors

Have you ever had the tops blow off of them? I had that happen when I was testing out Peter's attraction motor, I mistakenly wired it up and POOF the tops came flying off.

I may start testing various transistors on my Solid State Bedini now... I have rigged up a SSG that just just aligator clips to my transistors. Sure helps when I am trying to find out where the bad transistor is.

[dambit]

I have not had any probs with the 3055's however they can't handle as much abuse as the MJL21194's. I run the input at 24V and when the output is 12V they are ok for a second or two as long as the neon is attached, but on 24V output the neon may as well not be there, they fry almost instantly when the load is disconnected. I'm not sure why, but that's my experience.

[mlindeblom]

My experience with 2n3055's is that they have a large range of DCgain or Hfe values (i.e. 6 to 41).

My guess is that your varying results were due to DCgain variations.

Other transistor types such as MJ15024, MJ21194 or MJL21194 have higher voltage and power ratings, thus are more durable. The voltage rating is 250 volts versus 60. The power rating is 200-250 watts versus 115.