Sunday, April 19, 2015

What is Saturation in Transistors

Date 8/30/06 Simon and delabs
Simon: hello,anantha.
delabs: hello

Simon: we have many meanings for saturation,
delabs: means turning on, also means no longer linear, or it is got fixed up, not varying in accordance to any formula

Simon: that is what is concluded of. but we just wanted to be sure.
delabs: like you put salt in water. after some time no more salt can be dissolved, that is the state of saturation, In Electrical, no more relationship with V - I - R. Any increase in voltage or reduction it is same

Simon: thanks anan
delabs: anytime

What is Saturation in Transistors

Bipolar transistors are so named because their operation involves both electrons and holes. These two kinds of charge carriers are characteristic of the two kinds of doped semiconductor material; electrons are majority charge carriers in n-type semiconductors,

This concludes this episode of Saturated Talk with Simple Simon. Next week, a new Episode which will cover effects of Lightning Bolts.

To learn more about Saturation in NPN and PNP Devices see - Transistors Williamson Labs

Transistor Operation - A transistor in a circuit will be in one of three conditions

Chapter 5: Bipolar Junction Transistors

"Saturation also implies that a large amount of minority carrier charge is accumulated in the base region. As a transistor is switched from saturation to cut-off, this charge initially remains in the base and a collector current will remain until this charge is removed by recombination."

Lessons In Electric Circuits - Bipolar Transistors
When a transistor has maximum current through it, it is said to be in a state of saturation (fully conducting).

Saturday, April 18, 2015

Battery Boost Circuits

(This is a thread of my Google Talk many years ago - you will be able to notice text communication is quite difficult. sometimes even verbal expression will not specify the need, We need clear drawings and specs)

Sam: Hi! Anantha  I was going thrugh some IC like MAX8880/MAX8881, can u help me with using that with input from my batteries?
dapj: let me see

Sam: It's datasheet says that Supply current [Iin] = 10uA max does it mean it will draw a max of 10uA from my battery?

dapj: it looks like it will work from 2.5 to 12V and it can give you a 5v out 200ma
Sam: Exactly!
dapj: is 5V enough 200mA too, but it cannot boost voltage

Sam: my concern is with my input. What about using rechargeable batteries [4x1, 2100mAh] to act as input to this IC. will it consume 10uA if I do so while my load to the output may vary from 100mA to 200uA

Battery Boost Circuits Max8880

dapj: if you want 5V you need to feed this atleast 5.5V this chip does not consume anything (the uA is Standby consumption )but it is not a voltage doublet or a charge pump

Step-Up/Step-Down Converter Features Ultra-Low Quiescent Current

Sam: OK, I need to feed it anything between 5.5 -12V, Do we get recharge battery near about 2V, 2100mA
dapj - a 12 v battery can be recharged when 11.8V is reached it may charge upto 12.8 V in Li ion

Fast, smart NiCD/NiMh battery charger - The MAX713 is designed for NiCd batteries, while the 712 is for NiMh batteries.

Monday, April 06, 2015

Using LEDs with Battery Power

What are LEDs ? How can we use them for Long Battery Life

Mail from AD

If LED flashes at 5-10 K Hz at even 50% Duty Cycle. It may save some power and improve life. So it is just an idea, it may not solve the problem. The idea was to improve battery life and give uniform light for annunciators. It may not be good for flashlights.

Light-emitting diode - Wiki

Light-emitting diode - Wiki

LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.

The LED Museum

The LED (and Laser) Museum. A site devoted to testing & reviews of LEDs & LED flashlights in all common chemistries.

LEDs and OLEDs
Small lights with big potential: light emitting diodes & organic light emitting diodes.

Light Sources in Electronics
Light can be produced and/or controlled electronically in a number of ways. In light emitting diodes (LEDs), light is produced by a solid state process called electroluminescence.

Using LEDs with Battery Power