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Showing posts from November, 2012

NFB ( NO FUSE BREAKER )

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NFB (no fuse breaker) is one component of the electrical safety overload and short circuit. then what's the difference with the MCB ? be patient, we will discuss shortly. the  function can be seen from the above definition of the meaning of that is, as a means to disconnect ( break ) electrical current when the load handled by the these tools becomes overload or short circuit, or the current through it exceeds that limit has been set at the NFB . difference between the NFB with MCB is the limit value of current that can be served by both ini.MCB tool used for smaller load is typically modest and still can not diubah.sedangkan NFB has a larger current limit and used to secure his load currents more large and in some types of NFB anyone can set its current limit, of course, the greater the value of the current limit higher price NFB HOW NFB WORKS  Under normal circumstances: after the tool is set current limit permitted. pull the lever to the OFF position and Rev to the ON positio

Simple Touch Switch

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This is a simple touch circuit diagram.I think you can use this for many purposes.I have used this circuit as a security circuit device.Here I have used very common Transistors   2N 5458 N and 2N2222 to gain the signal .2N3906 Transistor work as a switch here. Note  # Build this circuit on a PCB # Use a copper plate to touch senseer  # Don't supply more than12V

Research on transformerless AC-AC (sine wave) conversion- Part 1: AC-AC Buck

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In Bangladesh, mains AC line voltage may vary quite a lot, sometimes down to about 180V (or maybe lower!) and sometimes up above 220V. Thus, using a voltage regulator/stabilizer is necessary so that the output voltage is fixed, if not exactly at 220V, somewhere around that. 210-225V is an acceptable range. The common method of AC-AC voltage regulation/stabilization is to use relays to switch the AC input voltage into different tappings of a transformer, so that the voltage is stepped up or down by an amount, as required, depending on the input voltage. There are 2 things in this circuit that could be improved: 1) Output voltage variation - Output voltage may sometimes vary by 10V or maybe even up to 20V. While, in most cases, it may be acceptable, a tighter regulation would certainly be better. 2) Cost - This type of stabilizer becomes quite expensive due to the large 50Hz transformer required. Also labor costs are high due to winding transformer with multiple tappings. So, for the las

Feedback in sine wave inverter (PIC16F series based)

I have previously shown how to calculate the values for the sine table: http://tahmidmc.blogspot.com/2011/01/generation-and-implementation-of-sine.html I have also shown how to implement SPWM in PIC16: http://tahmidmc.blogspot.com/2012/10/generation-of-sine-wave-using-spwm-in_10.html Now I will show how to implement feedback for SPWM. Due to various limitations in PIC16, such as ADC speed, instruction time and the ALU, it is extremely difficult, if not impossible, to calculate in real time the values required for feedback in sinusoidal pulse width modulation (SPWM). Thus, to implement feedback, a different approach must be used. That approach would be to retrieve the values from a sine table that contains the duty cycle values for a specific duty cycle. Here is one sine table I used, for example: const unsigned char sin_table[416]={ 0, 16, 32, 47, 62, 77, 91, 103, 115, 126, 136, 144, 151, 156, 160, 162, 163, 162, 160, 156, 151, 144, 136, 126, 115, 103, 91, 77, 62, 47, 32, 16, /

Controlling an AC load with a MOSFET

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In most cases where you want to control an AC load, a triac or SCRs will be used. However, it is not easy to drive a triac or SCR. The drive requirement for the triac or SCR makes it sometimes difficult to control it as we want. One thing is that we can not turn the triac or SCR on or off as we desire, because once we turn it on, it latches and stays on until the next zero crossing or until current stops flowing through it. Also, driving a triac with reference to MT1 (or A1) is not as straightforward as we would want. However, a MOSFET can be controlled as we want. Set the gate high (with a sufficient voltage) and current can flow from drain to source. Set the gate low and current can no longer flow. Convenient! However, a MOSFET can only be used to control DC loads since it is a unidirectional switch - current flow can be controlled when it is flowing from drain to source, but can not be controlled from source to drain. So, certainly it can not be used to control AC loads. Right? Well

Long time LED Flasher circuit diagram

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Today I'm going to going to show you a very wonderful circuit diagram .The special thing of this circuit is this circuit can light up a LED more than the normal time.Sometimes it will light up our LED more than one month.so I suppose this would be a good news for you guys.Here I have used very common Transistor 2N3904.When I was making this circuit I turned about  20 turns around the toroid. the wire was a small circuit wire.       Note # Build this circuit on a PCB  # Don't use more than 1.5V

DC motor control with PIC16F877A - Practical example of PIC PWM

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We all know what a motor is and what it does. The simplest way to run a motor is to just connect it to a power source. For a DC motor, that would mean, just connecting the motor to the DC voltage that the motor was rated for (or less). But, can you control the speed? Yes. The simplest method is to control the speed of the motor by controlling the voltage the motor runs off. Imagine we have a 12V motor. If you run it off 12V, you get maximum speed (you can get more at higher voltage, but let's not go over rated specifications!). So, simple logic dictates that as we decrease the voltage to the motor, the speed must decrease. You can use a simple LM317 regulator to adjust the voltage to the motor and thus the speed. But, this method of speed control has one huge disadvantage - inefficiency when using a linear regulator (and you may find the motor not running at all at lower voltages). Let's talk about the inefficiency. If we use a linear regulator to give 6V output f