How to test if your transistor is fried?

[iopplm]

Hi guys! I've just built myself a 3 coil monopole bedini motor after I bought a copy of Bendini Sg beginner's manual. I tweaked the number of copper wires 7+1 into (4+4+4)+1, which is 3 Spools of 4 x 115ft awg #20 copper wires + 1 x 115ft awg #23 copper wire in one of the spool. The reason why i got 115ft instead of 130ft because the copper wire I ordered online shortchanged me . Nevertheless, I fired up the system yesterday and it worked!

My primary battery is 18ah and my secondary battery is 26ah. I was getting good results for the initial testing. I was getting about -0.1V/30mins in the primary and +0.3V/30mins in the secondary batter. Then I tested my neon bulb for the safety feature, all 12 neon bulbs lighted. I thought "Checked, all safety bulbs are in place" . I did not measure the amps that the primary battery is supplying(I do not know if the discharging rate is slower than C20). I left the motor on through the night.

However, in the morning, when I checked the voltage in the pri and sec battery. I got -0.6V(12.29V) for the primary and +0.5V(11.89V) for the secondary. The COP dropped. I accidentally plugged out the secondary battery. I realized that only 7 Neon bulbs were lighted, the remaining 5 were not light up. I retested the safety features and confirmed that the remaining 5 bulbs were not lighting.

Some reasons I thought why the NE bulbs did not light up when I plug out the secondary battery.
1) Was it that the 5 transistors connecting to the 5 NE bulbs were fried?
2) Was it that after a night of running the voltage dropped and did not fire the 100V NE bulb
3) Was it some of the 115ft copper wires did not have enough length to fire the 100V NE bulb after the voltage of primary battery dropped through the night.

-Am I able to check if the transistor is fried by testing it with multi-meter without removing it from the board?
-How do I calculate C20 discharge rate for the batteries. Is it ah/20?

I would appreciate if anyone in the forum could help me out. Thank you !


Best regards,
Mark


This is a snapshot of my model. (all the circuit boards are on the top left of the model)

[D Rhodes]

Hi Mark, if you mean that while the system was running you detached the secondary battery , then yes I would say the transistors are burnt out.
Yes work with the C20 rate. Divide the aH by 20 to get it. So 18ah/20=900mA But if it is a starter battery and not a deep cycle, lowering that figure is safer...maybe 700mA. Someone else can answer it better than me.
Your primary only dropped 0.6v overnight...but what did your secondary start out at? Sounds like you may have something hooked up wrong? If your secondary was not charging overnight, but rather was being drawn down, then there may be a short circuit somewhere?
When I first started this stuff, we were only told to build a single bifilar coil, with only 1 mjl21194. And we mostly used 5ah or 10ah batteries. This way it works out cheaper when you are learning and burning out components! Once you learn what is going on with a simple 1 coil machine, then run your bigger one. That's my advice bro. Build a little machine with 1 coil and 1 trannie first. Get a couple of 7aH sealed lead acid batts and do some runs..
Dennis

[D Rhodes]

Also, where are the rest of your magnets? It will send more pulses with more magnets in those gaps.

[D Rhodes]

sorry, another thing I see with your build , ..place the circuit for each coil near each coil, thus keeping the wires as short as possible. The picture is a build by John Koorn ...notice how the circuits are all close to the coils? And also that copper common rails? You can hook each circuit up in series via this method for good conductivity, rather than having long skinny trigger and power wires like you have at present.

[James Milner]

Mark,
You can use an in circuit transistor tester. I use one available as a kit from www.jaycar.com.au. But I'm sure if you did a search you will find many others.
James

[iopplm]

Hi Mark, if you mean that while the system was running you detached the secondary battery , then yes I would say the transistors are burnt out.
Yes work with the C20 rate. Divide the aH by 20 to get it. So 18ah/20=900mA But if it is a starter battery and not a deep cycle, lowering that figure is safer...maybe 700mA. Someone else can answer it better than me.
Your primary only dropped 0.6v overnight...but what did your secondary start out at? Sounds like you may have something hooked up wrong? If your secondary was not charging overnight, but rather was being drawn down, then there may be a short circuit somewhere?
When I first started this stuff, we were only told to build a single bifilar coil, with only 1 mjl21194. And we mostly used 5ah or 10ah batteries. This way it works out cheaper when you are learning and burning out components! Once you learn what is going on with a simple 1 coil machine, then run your bigger one. That's my advice bro. Build a little machine with 1 coil and 1 trannie first. Get a couple of 7aH sealed lead acid batts and do some runs..
Dennis

Hi Dennis, thanks for the reply and advice! I'm still sourcing 6 more magnets to fit into the 17" wheel, making a total of 12 magnets on the wheel. My secondary battery started out at 11.4V after I drained it empty with 2 x 50W spotlights.

It was only a few seconds when I accidentally plugged out the secondary battery. Isn't the NE bulb suppose to be a safety feature if the secondary battery is plug out accidentally? Is there any way to check the transistor if it is burnt out, because it would whole lot of trouble to de-solder and re-solder a new one. Yes, I am using MJL21194 transistor too. If it were to short circuit, where would it be?

Yeah, I thought so. Making single bifilar coil. I suppose i was too ambitious. hahaha.

Would 7aH batteries be safer to run too?
Also, could you explain what is a deep cycle too?

Thank you!

[iopplm]

Mark,
You can use an in circuit transistor tester. I use one available as a kit from www.jaycar.com.au. But I'm sure if you did a search you will find many others.
James

Hi James,

Thanks for the link you gave! but can it be used when the transistor is connected to the circuit? Or I would need to take the transistor out and test it individually?

[iopplm]

sorry, another thing I see with your build , ..place the circuit for each coil near each coil, thus keeping the wires as short as possible.[ATTACH=CONFIG]3072[/ATTACH] The picture is a build by John Koorn ...notice how the circuits are all close to the coils? And also that copper common rails? You can hook each circuit up in series via this method for good conductivity, rather than having long skinny trigger and power wires like you have at present.

Why would shorter wires be better too?

[Tom C]

they are gonna have to change "testing the safety features" people are going to keep blowing transistors......

Mark you are discharging your charging battery way to much and at too hi of a load research C20 discharge rate.

Tom C

[Yaro1776]

Mark,

There is a mountain of information on the web about batteries, the different types and discharge info. Some links for you to digest.

http://www.rvpowersupply.com/interstate_batteries.htm
http://batteryuniversity.com/learn/
http://jgdarden.com/batteryfaq/carfaq9.htm#equalization

If you need more leads they can be provided...

This should keep you engaged for a couple of hours or perhaps years. A very basic understanding of battery characteristics is needed to appreciate the complexity of the SSG and its operation. It really is not rocket science (well maybe) and the instruction set on the forum is very comprehensive, but it requires your time and patience to ferret out the relevant details. The SSG Beginners Handbook is very comprehensive and gives one the necessary details to get things in motion, but some side research helps to complete the picture, if you will.

Your build ambitions are awesome, over the top! As you see though, there is more to this experiment than meets the casual eye. It is like "eye candy", looks really good, but gets very complex under the hood.

Keep plugging Brother,
Yaro

[iopplm]

they are gonna have to change "testing the safety features" people are going to keep blowing transistors......

Mark you are discharging your charging battery way to much and at too hi of a load research C20 discharge rate.

Tom C

Hi Tom,

I thought so too! From the forum, they always warn the beginners NEVER unplug the secondary battery. I think even with the NE bulbs installed, unplugging will secondary battery will still blow the transistor at a very high chance.

Regarding C20 discharge rate, I should then get a larger batteries to test it? Since it is radiant energy, there will be no amp. How do we calculate for C20 rates for charging?

Thank you!

[iopplm]

Mark,

There is a mountain of information on the web about batteries, the different types and discharge info. Some links for you to digest.

http://www.rvpowersupply.com/interstate_batteries.htm
http://batteryuniversity.com/learn/
http://jgdarden.com/batteryfaq/carfaq9.htm#equalization

If you need more leads they can be provided...

This should keep you engaged for a couple of hours or perhaps years. A very basic understanding of battery characteristics is needed to appreciate the complexity of the SSG and its operation. It really is not rocket science (well maybe) and the instruction set on the forum is very comprehensive, but it requires your time and patience to ferret out the relevant details. The SSG Beginners Handbook is very comprehensive and gives one the necessary details to get things in motion, but some side research helps to complete the picture, if you will.

Your build ambitions are awesome, over the top! As you see though, there is more to this experiment than meets the casual eye. It is like "eye candy", looks really good, but gets very complex under the hood.

Keep plugging Brother,
Yaro

Hi Taro,

The links are useful! That would answer most of my questions on batteries.
Yes, SSG beginners Handbooks is very comprehensive. Still have a lot to understand the science behind it. After I've made the first one working, am getting addicted and already thinking of making 4 or 8 coils designs. hahaha. Gonna save up, copper wires ain't cheap. :/

Thanks for the compliment too! It motivates someone like me, first time builder.


Best Regards,
Mark

[James Milner]

Mark,
An in circuit transistor tester can test while "in circuit" but not operating. That is battery disconnected.
That being said be wary of "damaged but operational transistors". i.e the junction is affected and the gain (HFE) is not what it was!

To alleviate these difficulties I now use a socket for transistors so I can pull them out at any time and retest. Costs is about $3 each here in Australia but worth the peace of mind.
James

[Tom C]

Hi Tom,

I thought so too! From the forum, they always warn the beginners NEVER unplug the secondary battery. I think even with the NE bulbs installed, unplugging will secondary battery will still blow the transistor at a very high chance.

Regarding C20 discharge rate, I should then get a larger batteries to test it? Since it is radiant energy, there will be no amp. How do we calculate for C20 rates for charging?

Thank you!

you need C20 rate for running the frontside of the SG and a C20 when discharging the secondary battery. its all done with standard calculations, don't worry about the radiant component cannot be measured anyway.

Tom C

[iopplm]

Mark,
An in circuit transistor tester can test while "in circuit" but not operating. That is battery disconnected.
That being said be wary of "damaged but operational transistors". i.e the junction is affected and the gain (HFE) is not what it was!

To alleviate these difficulties I now use a socket for transistors so I can pull them out at any time and retest. Costs is about $3 each here in Australia but worth the peace of mind.
James

Hi James,

Great idea! A transistor socket. Shall source for one. Anyway I de-solder the transistors to check if it's blown. It turns out that they're OK! I suppose the dropped in voltage in the primary battery and short copper wires of 115ft didn't raise the voltage high enough to fire the NE bulb.

Best Regards