How to Test Diode & transistor leakage

Status
Not open for further replies.
Re: Testing Diode leakage & transistor leakage

Maybe it is time for you to look at the maximum allowed temperature of the chip inside an IC and compare it to the temperature of the tip of your soldering iron.
A HUGE difference.
 

Re: Testing Diode leakage & transistor leakage

Do you put a Heatsink clip on transistors that are the black plastic package?

Do you put a heatsink clip on a IC dual in-line package, 14 pin or 16 pin IC chip dual in line package? does these need the heatsink clip too?

If you put the headsink clip on the transistors or IC dual in line package on the body black plastic package, does it really help with the heat?
 

Re: Testing Diode leakage & transistor leakage

The first link is for a TO-220 packaged power device, it is useless as desoldering heat sink. The other two are OK, I use one similar to the 7" one, it clips directly on to the leg you are desoldering so it dissipates some of the heat travelling up it and delays it reaching the device itself.

Your assumption that freezing and heating transistors will repair them is absolutley flawed!

Brian.
 

Re: Testing Diode leakage & transistor leakage

I have used a temperature-controlled Weller soldering iron for 48 years and never used a heatsink when soldering. NOTHING has been damaged.
Maybe Billy (Danny?) is using a cheap soldering iron without temperature control that gets much too hot or (gasp!) a soldering GUN or a propane plumber's torch?
 

Re: Testing Diode leakage & transistor leakage

There are a few sensitive components that might require extra caution. Besides old germanium semiconductors some sensor devices.

You find special heatsink tweezers for handling of these devices in tool manufacturer catalogs.
 

The IC op amps at work on this board at

LM101
LM124
LM108

They all need the capacitor added for the comparators so it won't oscillate the output

What is the main difference between these 3 Op amps? besides GAIN and bandwidth, what would be the purpose to use these 3 ? why not stick to one op amp through out the circuit? plus it would be cheaper
 

You did not look at the datasheets and you still do not understand why an opamp uses a compensation capacitor and a comparator does not.

The LM101 is a single very fast opamp. Its external compensation capacitor can be selected small to have high gain and be fast, or with a higher value to have low gain, be fast but not oscillate.

The LM124 is a quad slow opamp that has built-in compensation capacitors. NO quad opamp has pins for external capacitors. It is unusual because its inputs work all the way down to ground and its output goes almost all the way down to ground.

The LM108 is very old and I have never seen one. Why don't you read its datasheet?
It has low input bias current and low input offset voltage. It has a very high input resistance.

See, all these old opamps are very different to each other.
 

NO quad opamp has pins for external capacitors. It is unusual because its inputs work all the way down to ground and its output goes almost all the way down to ground
Click to expand...

Why does the inputs and outputs go almost to ground? What's the reasons? is this only for Quad amps only?

The LM108 is very old and I have never seen one. Why don't you read its datasheet?
It has low input bias current and low input offset voltage. It has a very high input resistance.
Click to expand...

When An Op amp has a high input resistance how it that different than the rest, what does it do differently?
WHen an Op amp has low input bias current how it that different , what does it do differently? than an op amp that has High input bias current?
When an Op amp has low input offset voltage, what does it do differently, than an op amp that has High input offset voltage?
 

danny davis said:
Why does the inputs and outputs go almost to ground? What's the reasons? is this only for Quad amps only?
Click to expand...
If the opamp power supply is single polarity then frequently it is best to have the inputs still work properly when they are very close to ground and have an output that goes down to ground.

An LM124 is a quad opamp, an LM158 is a dual opamp and there was a single one. The opamps in them are all exactly the same.
They all have an internal compensation capacitor. They are all slow because they use a low amount of power for long life battery operation.

Please go back to school and learn this simple stuff.

How on Earth can you WORK in electronics when you know NOTHING about electronics??
On the other website where you were asking the same questions as here the Super Moderator called you a TROLL. Then that thread was closed.
 

If the opamp power supply is single polarity then frequently it is best to have the inputs still work properly when they are very close to ground and have an output that goes down to ground.
Click to expand...

What is the reason for the input to be close to ground and the output that goes down to ground? what is the reason for it?


They didn't teach us this, because they said this is R&D electronic and you don't need to know this stuff
 

danny davis said:
What is the reason for the input to be close to ground and the output that goes down to ground? what is the reason for it?
Click to expand...
..because the application often demands it.



They didn't teach us this, because they said this is R&D electronic and you don't need to know this stuff
Click to expand...
They were wrong.
 

danny davis said:
What is the reason for the input to be close to ground and the output that goes down to ground? what is the reason for it?
Click to expand...
Many reasons.

They didn't teach us (opamp input resistance, input bias current and input offset voltage) because they said this is R&D electronic and you don't need to know this stuff
Click to expand...
Then why do you ask? You are not designing and you are not doing R&D. You are just a repair guy who doesn't know ANY of this stuff.
 

Cause I want to know so I can understand circuits better
 

Before going further, please tell us who or where you were taught electronics. It's somewhere we should tell people to avoid.

For the record: I was never given any tuition whatsoever, I was also a high school drop-out with no relevant qualifications. I learned by reading and experimentation and to this day I have no qualifications, yet I have been head-hunted by major international companies and worked in many countries on R&D and development work. I'm now officially retired yet have a long list of research projects to complete. All this means that you are probably more qualified, at least on paper, than I am. Believe me, if the school idiot (me) can learn, surely you can.

Brian.
 

betwixt said:
Before going further, please tell us who or where you were taught electronics. It's somewhere we should tell people to avoid.
Click to expand...
On the other website, members wanted to know which airplanes to avoid that use the control circuits he is "repairing" (destroying).
Since he is still a beginner then maybe (hopefully) they throw away everything he has worked on.
Maybe he is "training" on repairing old junk from the 60's and 70's that will never be used again.
 

Can you please help on this

If the opamp power supply is single polarity then frequently it is best to have the inputs still work properly when they are very close to ground and have an output that goes down to ground.
What is the reason for the input to be close to ground and the output that goes down to ground? what is the reason for it?

When An Op amp has a high input resistance how it that different than the rest, what does it do differently?
WHen an Op amp has low input bias current how it that different , what does it do differently? than an op amp that has High input bias current?
When an Op amp has low input offset voltage, what does it do differently, than an op amp that has High input offset voltage?
They didn't teach us this, because they said this is R&D electronic and you don't need to know this stuff
 

Many reasons.

I also answered these simple questions already (on another thread here?).
 


Where is the thread ? or just retype it , it should take long to answer them quick
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…