Circuit Diagram Knowledge: dc

Showing posts with label dc. Show all posts

Monday, November 17, 2014

DC Motor Speed Control using PWM

The so-called PWM or Witdh modulation is a technique often used to control a load, for example, is the control of DC motor speed PWM techniques are used frequently.

Usually to make a simple PWM (for practice or the introduction PWM) fans to use some of the facts of the op-amp circuit, which consists of Schmitt Trigger circuit, the integrator and comparator.

Schmitt Trigger function that produces a square wave will become the sawtooth wave or integrator is also called common rail and the ramp compared to a reference voltage that can change a lot of stress. So the result is a PWM output.

These two schemes are variations of different circuit PWM. The diagrams are for 12V operation and there are upper (ground) and low side (+12 V common) versions. The version of the lower circuit uses an N-channel FET, the high-side version of the circuit uses a P-channel FET. N channel devices tend to handle more current P-channel devices, which are also less expensive. The version of the high side of the circuit is useful when a portion of the load must be grounded.

This circuit can change a fairly high amount of current, a MOSFET IRFZ34N can handle over 35 Amps if connected to an adequate heat sink. Higher power FETs, such as IRF1010Z IRFZ48N or can be substituted if even larger currents are required. It is also possible to connect multiple FETs in parallel even more current capacity. Always use thermally conductive grease between the FET and the heat sink, and remember that the heatsink is under stress.

Inductive loads (motors) may require special care because it can generate large voltage spikes that can damage the MOSFET. Replacing a 1N4002 fast recovery diode can help absorb the recoil reverse voltage when driving an inductive load like a motor. If you use these circuits to experiment with electric vehicles, be sure to install a circuit breaker in series with the battery, the switch should be easy to reach by the driver. This is especially important given the fact that when non-MOSFETs, is often cut, leaving the engine running at full speed

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Wednesday, November 12, 2014

LM317 based DC motor speed controller with circuit

A very simple DC motor speed controller circuit can be constructed using a LM317 voltage regulator integrated circuit . This DC motor speed controller can be used for speed control of mini drills or for other small DC motors . This motor controller circuit will provide a large output current . The maximum output current from the secondary turns of the transformer shout provide 1.5 times of the maximum DC output current . The output voltage and the speed ( rpm ) is set by the P2 variable resistor .

As soon as the current drawn exceeds a certain value , T2 will be switched on . This results in a base current for T3 so that R5 is in parallel with R6 . This automatically raise the output voltage to counter a threatened drop in rpm . The moment at which this action occurs is set by P1 .

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Sunday, October 5, 2014

Universal Laptop Power Supply AC DC Adapter

One of the things you may not think about when buying a new laptop is what will happen if you lose your laptop AC adapters. Sure this does not seem like something you would lose, but it is very easy to misplace. So it is always a good idea to know where to buy another one, or even have another one handy just in case something like this should ever happen.

If you are going to buy laptop AC adapters online you need to make sure it is the right one. The one that comes with the computer is, of course, the best one to have for it, however, if you buy one online just make sure it is going to fit your computer.

Also, be sure that it is a good model of laptop AC adapters. Some of them can get too hot and overheat. The best thing to do is read some online reviews of the notebook battery chargers, and see which ones work the best. From there you can choose the one that you are going to need. I think it is always a good idea to have a back up anyway. Nothing is worse than having a laptop and not being able to use it. So do not let that happen to you. Go out and get an extra one today.

Replacing notebook power supplies is sometimes an expensive process as it the purchase of an air/auto power supply for your laptop. However for those users who need a new power supply for their notebooks or for users planning to travel, Targus have available a Universal adapter series called the Universal 70 Watt AC/DC Power Adapter that gives the user a variety of ways to power their notebooks.

Features

Power on the go, anywhere: Works at home, office, car, boat, or aeroplane.
Lightweight design: At just 213g, this adaptor is lightweight, compact and ideal for travel.
Compatible with other mobile devices: With the optional Targus Accessory Powering System and device tips, you can power your mobile phone or PDA as well as your notebook.

Basically the Universal 70 Watt AC/DC Power Adapter allows you to plug your laptop into a car cigarette lighter, an aero plane power seat system or into the mains to give your notebook the electricity needed to run the unit. Best of all, the device is 98% compatible with popular 70W notebooks and covers a whopping 6,300 models.Visit Tagus Website

Technical Specifications

Compatibility: Airline Compatibility Chart Always call your airline to confirm inflight power seat system and Targus auto/air compatibility.
Varied models of Acer, Apple, Compaq/HP, Dell, Fujitsu, IBM, Panasonic, Sony and Toshiba.
Other: Includes9 tips 91cm AC input cord 91cm DC input cord 1.82m DC output cord User guide.
Size: 13.7 x 5.5 x 2.2 cm.
Technical: 100-230 VAC 11.75-16.00 VDC.
Warranty: Limited Two Year Warranty.
Weight: 213g

Targus Universal 70 Watt AC/DC Power Adapter is a must have device for those notebook users who travel or even for users that need a second power supply for their PC. The unit is relatively quite small and does not weigh much which is perfect for users on the go.

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Wednesday, December 25, 2013

3 3V And 5V Outputs Dc Dc Converter Circuit Diagram

This is the 3.3V And 5V Outputs - Dc-Dc Converter Circuit Diagram. This Input, voltages can range from 8 V to 30 V. The load range on the 5 V is 0,05 A to 5 A while the 3.3-V load range is 0.1 A to 1 A. The circuit is self-protected under no-load conditions. Over all load and line conditions, .including cross regulation, the 3.3-V output varies from 3.25 V to 3.27 V. The 5-V output varies from 4.81 V to 5.19 V under the same conditions.

In a typical application to 0.5 A on the 3.3 V and 0.25 A on the 5 V, efficiency is typically 76%, With an input voltage of 30 V and a full-load condition, the efficiency drops to 66%. In normal operating regions, efficiency is always better than 70%.The 5-V ripple is less than 75 mV and the 3.3-V ripple less than 50 mV over all line and load conditions.

3.3V And 5V Outputs - Dc-Dc Converter Circuit Diagram

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Tuesday, December 24, 2013

12Volt to 9Volt DC Converter

To get a more precise output voltage, replace zener diode Z1 with 10V and R1 with a 1Kilo ohm potentiometer. A Coolrib for Q1 is optional but highly recommended. You can replace Q1 for a more robust type to get more output amps depending on your requirements. Simple circuit to power your 9 volt cassette recorder and other stuff.

Parts List:
R1 = 560 ohm
C1 = 1000uF/40V, Electrolytic
C2 = 10uF/25V, Electrolytic
C3 = 330nF, Ceramic
Z1 = 9.1V, 1watt zener
Q1 = ECG184, NTE184

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