Technical-Reference

delabs Notes – In a Circuit Module, if all Power and Signal Polarities are reversed. All NPN to PNP, All N-Channel to P-Channel and Vice Versa. All Diodes and Caps too turned around. This Topsy Turvy or Mirror Design ought to work in Theory. It has worked for some circuits in practice too in my experience. ?

Some believe that N-Channel is more Robust than the P Type. In Bipolar Transistor NPN is more trusted for the final output stages. The NPN Transistor and N-Channel turn-on by a Positive control bias. It may be inappropriate to say this mosfet is NPN or PNP.

The MOSFET in Power Electronics

The traditional metal–oxide–semiconductor (MOS) structure is obtained by growing a layer of silicon dioxide (SiO2) on top of a silicon substrate and depositing a layer of metal or polycrystalline silicon (the latter is commonly used). As the silicon dioxide is a dielectric material, its structure is equivalent to a planar capacitor, with one of the electrodes replaced by a semiconductor.

If the MOSFET is an n-channel or nMOS FET, then the source and drain are “n+” regions and the body is a “p” region. If the MOSFET is a p-channel or pMOS FET, then the source and drain are “p+” regions and the body is a “n” region. The source is so named because it is the source of the charge carriers (electrons for n-channel, holes for p-channel) that flow through the channel; similarly, the drain is where the charge carriers leave the channel. MOSFET – Wikipedia

This application note discusses the breakdown voltage, on-resistance, transconductance, threshold voltage, diode forward voltage, power dissipation, dynamic characteristics, gate charge and dV/dt capability of the power MOSFET.
Application Note AN-1084 Power MOSFET Basics – IRF

A MOSFET is a transistor. It is a Metal Oxide Field Effect Transistor. Here are the symbols for FETs and MOSFETs: The MOSFET How the MOSFET works

The conductivity of the path from Source to drain is controlled by applying a voltage between the gate and the body of the semiconductor. N-channel enhancement MOSFET

See this simple circuit that explains everything
n-channel MOSFET switch – George Watson, Univ. of Delaware, 1996.

Providing detailed electronic design information regarding Interface, Computer, Cable, Processor and Embedded Buses. – Leroy Davis

Buses used on Personal Computers, Computers & Peripherals, Standards, Wireless, Logic Design.

interfacebus.com – Interface and Cable design

The site is geared toward Engineers who develop or design equipment. There are 3 main sections; OEM Equipment / Components listings, Computer buses, and engineering design data.

In this site you will find a wealth of knowledge regarding Analog and Digital Integrated Circuits; Memory, Processor and Programmable Logic IC’s, Bus Interface IC’s,  Passive, and Mechanical components; Resistors, Capacitors, Inductors and Sensors, EDA Software vendors,

interfacebus.com - Interface and Cable design

PCI104 Bus

PCI-104 is the newest variation of the standard. PCI-104 removes the old PC XT / AT bus from the specification leaving only the PCI bus. The PCI bus connector is a 4×30, 2mm stack-through connector. PCI-104 cards may still reside in a stack with either PC/104 cards or PC/104-Plus cards.

This is a way by which you can monitor the level of fluids like water in a tank. Based on data from the sensor you can control things like solenoids or motors as required or even turn on a buzzer, hooter or annunciator in a control panel. A simple Water Level Controller.

Description.

Look at the picture on the right, the float can be a Styrofoam type with a couple of ceramic magnets stuck inside. The float must move freely up and down a long plastic pipe of around 10 mm dia. If the fluid is not water but a solvent then design a non-soluble float or coat the float you made with something like an epoxy resin.

Water Level Controller

Then you need to assemble a small circuit within the long plastic pipe. Many reed relays with a chain of resistors in series has to be inserted in the pipe. The resistor and the glass reed relays should be in different levels of the pipe where you need an alarm or indication. Seal the pipe hermetically at both ends with epoxy resin after taking out a shielded cable of just 2 wires + 1 ground shield.

When the fluid level changes, the float moves up or down with it, when the float moves over a section of pipe where the reed relay is mounted, the magnets on the float make the reed operate and the resistance of the sensor changes.

The resistance is measured and the alarm can be operated as you like. The advantage of this arrangement is the electric circuit does not come in contact with the fluid, no sparking risk.

Reed Relay. It was invented by Dr. W. B. Ellwood at Bell Labs in 1936. Contacts are in a sealed glass tube filled with inert gas like in a bulb, so they do not corrode. It is faster than regular relays and as no spring is used it has a longer mechanical life. The two contacts are ferromagnetic blades plated with rhodium. When you take a magnet close by, the contacts touch each other. You can also put the reed in a coil, then when you energize the coil the reed operates. Used in telecommunication.OKI is one manufacturer of this type of component.

Design and Caution.

When you drive inductive loads you have to use RC snubbers, freewheeling diodes, varistors or zeners. when you drive lamps the cold current is high so use thermistors. The Reed relay is best used in telecom and instrumentation and avoided in power electronics. It can handle high RF frequency as the path of current is straight and footprint small.

Here is a Circuit to Build and Learn this Concepts – This can help make a Water level controller from sump to overhead tank. This can also be used in industrial fluid level control like oils and thick fluids. It may not work with highly viscous fluids or sticky mixes.

Fluid or Water Level with Reed Relays

“When you use the DMM or digital multimeter, try not to use it for high voltages and currents, use external shunts and attenuators instead. If you try to measure 230V AC in the Ohms mode or in the Current mode with the probe in the current socket then you will see fumes in your DMM and a hole in your pocket !!”

– Solderman Talks 1702

Since 1978, Wenzel Associates has defined the state-of-the-art in ultra-low phase noise while providing system manufactures with the highest quality, cost effective frequency components and instruments.

Wenzel Associates introduced the Blue Tops system building blocks to offer oscillator users well-characterized, low noise components, which improved the time to market for new frequency based systems.

Wenzel Associates Technical Library

  • Time and Frequency Circuits and Articles including frequency synthesis and conversion.
  • Crystal Oscillator Tutorial Articles cover oscillator types, terminology, and selection.
  • Spreadsheets/ Programs to calculate pll response, phase noise under vibration, and others

Phase Noise Measurement

Wenzel Associates Technical Library

“The measurement technique compares the phase of an oscillator under test to a reference oscillator with similar or superior noise performance.”

Wenzel Associates, Inc
2215 Kramer Lane, Austin, TX 78758, USA

The JFET-input operational amplifiers in the TL07x series are designed as low-noise versions of the TL08x series amplifiers with low input bias and offset currents and fast slew rate.

Quadrature Oscillator – 100 kHz – TL072-TI – TL072-TI  Opamp

TL072-Quadrature Oscillator.png

The low harmonic distortion and low noise make the TL07x series ideally suited for high-fidelity and audio preamplifier applications. Each amplifier features JFET inputs (for high input impedance) coupled with bipolar output stages integrated on a single monolithic chip.

Dual-Low-Noise-JFET-Opamp-TL072-TI

Low Power Consumption
Low Input Bias and Offset Currents
Low Noise
High Input Impedance JFET Input Stage
High Slew Rate – 13 V/µs Typ
Common-Mode Input Voltage Range Includes VCC+

The circuit is a two stage sequential timer with auto reset. It can turn a Solenoid On/Off after a Sequence of delays that are preset. This is also a basic example of timer usage in automation.

Design Documents

Source Files Orcad Format

All Timers are 1 – 30 Secs Analog with Presets to adjust with a screwdriver. The Switch, Solenoids and Power supply has to be via terminal blocks or plug-jacks. The PCB may be upto six Square Inches for standard DIP components but with SMD it may be smaller.

Block Diagram :

Sequential Timer Specs

The PCB has to be tested to conform with the circuit, this has to be Meticulous. The Circuit is for the Battery and Solenoid Specified and will have to be modified if battery and solenoid are different. D1 to D4 can be replaced by a 300V 3A Bridge Rectifier Module. F1 fuse could be 2A – 3A Slow Blow depends on Solenoid inrush current. Presets can be with some graduations if possible for ease of adjustments. LED resistors can be a bit lower if more brightness is required.