Electronic Engineering
Electronic Components
Resistor
Capacitor (Ceramic, Electrolytic)
Diode
Transistor (NPN, PNP)
MOSFET (N-Channel, P-Channel
OP-AMPs
SMDS (Surface Mount Devices
Inductors
Voltage Regulator
Transformers
Differential Voltage ( + 15 / -15,
Technical Knowledge
Ohm's law
Kurcheff's current/voltage law
Push Pull -
2 Emitter Follower
No voltage but Current Gain
+ve
NPN ( +ve top half of wave) source PUSH current to the load, Vbe
PNP (-ve botton half of wave) PULL the current from the load
-ve
Middle Terminal is the Collector
Flow of Signal on A Push-Pull Amplifier using a NPN and PNP
+ ve ((90Volts) - Class G amp - switch on when more than +45volts need )
mosfet N-Channel IRFOP9140N (Gate Drain Source)
NPN C5240
+Ve (+45Volts)
Collector
Base +0.6volts Bias (Needs +ve wave to turn on)
Emitter
=> 0.22Ohm => SPEAKER
=> 0.22Ohm
PNP A1962
Emitter
Base -0.6 volts bias (Needs -ve wave to turn on)
Collector
-ve (-45Volts)
Mosfet P-Channel IRFP9150N (Gate Drain Source)
- ve (-90Volts) - Class G amp - switch on when more than -45volts need )
https://www.youtube.com/watch?v=JokusaT7eok&t=1534s
https://www.youtube.com/watch?v=S7jrirsfkNw&t=20s
How to identify PNP or NPN Transistors
Emitter, Base, Collector
P (Positive)
N (Negative)
P Positive
BC547 BC157
N P N P N P
you'll have 0.7 ohm reading with NP or PN junction is Good and no reading if terminal leads change.
Base + Base -
Emitter - Emitter +
Collector - Collector +
NPN - Red Led on Base and Black led on Emitter or Collector you will have .6 ohms
- Black Led on Base and Red led on Emitter or Collector you will have No Reading
PNP - Black Led on Base and Red led on Emitter or Collector you will have .6 ohms
- Red Led on Base and Black led on Emitter or Collector you will have Mo Reading
Meter in Diode Mode
Red Led (Voltage/Ohm)
Black Led (Common)
meter reads O.L is Over Limit. eg . So if you are on a 2 V voltage range and try to measure 3 V, it will show OL.
Identifying the PNP Transistor
We saw in the first tutorial of this transistors section, that transistors are basically made up of two Diodes connected together back-to-back.
We can use this analogy to determine whether a transistor is of the PNP type or NPN type by testing its Resistance between the three different leads, Emitter, Base and Collector. By testing each pair of transistor leads in both directions with a multimeter will result in six tests in total with the expected resistance values in Ohm’s given below.
1. Emitter-Base – The Emitter to Base should act like a normal diode and conduct one way only.
2. Collector-Base – Collector-Base junction should act like a normal diode & conduct one way only.
3. Emitter-Collector – The Emitter-Collector should not conduct in either direction.
Then we can define a PNP Transistor as being normally “OFF” but a small output current and negative voltage at its Base ( B ) relative to its Emitter ( E ) will turn it “ON” allowing a much large Emitter-Collector current to flow. PNP transistors conduct when Ve is much greater than Vc.
In other words, a Bipolar PNP Transistor will ONLY conduct if both the Base and Collector terminals are negative with respect to the Emitter
In the next tutorial about Bipolar Transistors instead of using the transistor as an amplifying device, we will look at the operation of the transistor in its saturation and cut-off regions when used as a solid-state switch.
Bipolar transistor switches are used in many applications to switch a DC current “ON” or “OFF”, from LED’s which require only a few milliamps of switching current at low DC voltages, or motors and relays which may require higher currents at higher voltages.
visual inspection of board
- Look for burn components
- Loose connections
- Capacitors bulging
- Missing components
- Cold solder joints
- Cracked solder joints
5/8" Plywood Front Panel
Empty 15 Inch Speaker Cabinet with Titanium Horns
MODEL:SA-15T_Empty
CONTENTS:Empty 15 Inch PA/DJ Speaker Cabinet
CONDITION: New
APPLICATION: PA Speaker | Main | PA Loudspeaker | Live Sound
ACTIVE/PASSIVE: Passive
TWEETER/HORN: 1.5" Titanium Tweeter Driver with 10 oz Magnet and 1" Throat
CROSSOVER FREQUENCY: 12/18 dB per octave, 3 kHz High Power with Dual glass bulb tweeter protection
CONNECTORS:Two 1/4" and Two Speakon
NOMINAL IMPEDANCE: 8 Ohms
GRILL: Full Metal Grill
HANDLES: Recessed Plastic
ENCLOSURE: 5/8" Plywood Front Panel
POLE MOUNT: Yes
CABINET CUTOUT DIMENSIONS: 13 7/8"
HEIGHT: 29"
WIDTH: 18"
DEPTH:15"
WEIGHT: 34.7 lbs per Cabinet
incoherent, bad memory,
Reference
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