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Type: Posts; User: c_mitra

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1. ## Thread: Calculating electromagnet – magnetism vs heat

by c_mitra
Replies
6
Views
103

### Closed: Re: Calculating electromagnet – magnetism vs heat

You will be generating about 50W (dissipation); this must be dissipated.

Your screw is 1 cm in diameter but you have not said anything about the length.

I assume the 500 turns are made in one...
2. ## Thread: carbon arc modalities

by c_mitra
Replies
9
Views
295

### Closed: Re: carbon arc modalities

But this is typically a blackbody radiation. The temp can be computed using the power input and the thermal mass.

The ionization is caused by the electrons- and they are not having the same...
3. ## Thread: carbon arc modalities

by c_mitra
Replies
9
Views
295

### Closed: Re: carbon arc modalities

Why do you think so?

In basic operation, carbon arcs are like discharge lamps. Say a fluorescent lamp or a neon bulb. All discharge lamps love constant current operation mode.

Carbon arcs work...
4. ## Thread: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

by c_mitra
Replies
5
Views
413

### Closed: Re: Potential Energy and Kinetic Energy of an Electron in an Energy Band diagram

Before I try to explain, I must tell you that the two terms Kinetic and potential (energies) are basically Newtonian in origin. They are related to dynamics and you need to understand the concept of...
5. ## Thread: Calculating electromagnet – magnetism vs heat

by c_mitra
Replies
6
Views
103

### Closed: Re: Calculating electromagnet – magnetism vs heat

I suggest the following steps:

Estimate the current and number of turns (NI is more important). You need to see that the core is able to handle the magnetization without saturation.

Look at the...
6. ## Thread: Halogen Lamp Limit Resistor?

by c_mitra
Replies
15
Views
412

### Closed: Re: Halogen Lamp Limit Resistor?

Nichrome or Kanthal wires can dissipate greater heat for smaller length. Also, they have higher resistivity and hence will need shorter length. Plus, they have a smaller temp coefficient.

Also,...
7. ## Thread: Stacking diodes for high voltage rectification

by c_mitra
Replies
27
Views
642

### Closed: Re: Stacking diodes for high voltage rectification

They should work if you can keep the reverse power dissipation within limits. What is the load you are going to use?
8. ## Thread: Halogen Lamp Limit Resistor?

by c_mitra
Replies
15
Views
412

### Closed: Re: Halogen Lamp Limit Resistor?

Halogen lamps are not designed to be run at lower power. Lower power means lower filament temp and lower filament temp means poor iodine recycling (WI3) and that will cause the glass (quartz) cover...
9. ## Thread: Bridge Rectifier won't Rectify

by c_mitra
Replies
26
Views
641

### Closed: Re: Bridge Rectifier won't Rectify

Compensation ideally works only for a fixed frequency. Why the frequencies seen in post 14 for the square pulses are so low?
10. ## Thread: Pulse transformer output measured vs. calculated?

by c_mitra
Replies
23
Views
612

### Closed: Re: Pulse transformer output measured vs. calculated?

No, I do not wish to know the internal details. I just want to know if you substitute a resistor instead of the pulse transformer, what kind of waveform you will get? say you use a 1k or 10k resistor...
11. ## Thread: Bridge Rectifier won't Rectify

by c_mitra
Replies
26
Views
641

### Closed: Re: Bridge Rectifier won't Rectify

For low frequency (say 50-60Hz), you can protect the diodes with capacitors and resistors. They help suppress spikes.

The capacitor cannot be used for high frequency. I do not know other ways to...
12. ## Thread: Toroids EMI suppression choce choice of core material ?

by c_mitra
Replies
3
Views
165

### Closed: Re: Toroids EMI suppression choce choice of core material ?

As an inductor you can use either one. Obviously the smaller one is cheaper and equally effective.

But you do not mention the power to be handled.

Yes, a lot of power is going to come back to...
13. ## Thread: Pulse transformer output measured vs. calculated?

by c_mitra
Replies
23
Views
612

### Closed: Re: Pulse transformer output measured vs. calculated?

Once you use a voltage divider, your bandwidth is also getting scaled down in the same ratio, right? Similar to gain-bandwidth product

Plus, frequency compensation should be done with this divider...
14. ## Thread: Pulse transformer output measured vs. calculated?

by c_mitra
Replies
23
Views
612

### Closed: Re: Pulse transformer output measured vs. calculated?

I am not quite sure. How are you generating the pulse?

The waveform seen is typical ringing process (it hit a bell and it produces sound that slowly dies in intensity).

I still suspect that the...
15. ## Thread: Bridge Rectifier won't Rectify

by c_mitra
Replies
26
Views
641

### Closed: Re: Bridge Rectifier won't Rectify

The first peak is around 8 kv; the current should be around 270mA. The diodes are not rectifying.

In the previous graph, with a load of 100Mohm, you get currents of the order of microamps. Small...
16. ## Thread: Pulse transformer output measured vs. calculated?

by c_mitra
Replies
23
Views
612

### Closed: Re: Pulse transformer output measured vs. calculated?

In response to a voltage pulse, the current increases linearly; that is clearly seen in the graph.

In both the plots, I see considerable high frequency ringing. Both voltage and current plots show...
17. ## Thread: Bridge Rectifier won't Rectify

by c_mitra
Replies
26
Views
641

### Closed: Re: Bridge Rectifier won't Rectify

I suspect that the voltage is not getting shared equally by the diodes. You need to put resistors in parallel with the diodes so that the applied voltage is divided equally.

The value of the...
18. ## Thread: dc motor theory question??? Maths

by c_mitra
Replies
3
Views
288

### Closed: Re: dc motor theory question??? Maths

I really do not know where to start.

But you have calculated somehow; tell us the steps.

Once we know the steps we can comment.

How to convert the motor torque 40nm to watts?

Is it a DC...
19. ## Thread: magnet wire parasitic properties

by c_mitra
Replies
5
Views
252

### [SOLVED]Closed: Re: magnet wire parasitic properties

Ferrites are soft or hard depends on their magnetic properties. Yes, they are not "soft" materials, because you will take lots of time to cut one.

Just like soft iron does not store magnetism, it...
20. ## Thread: Subtract two dc voltages.

by c_mitra
Replies
8
Views
397

### Closed: Re: Subtract two dc voltages.

I am confused: how it is going to work in real life?

You are connecting to batteries in series but measuring the voltage across the 9V battery.

Am I missing something?
21. ## Thread: Single conductor inside hollow conductor

by c_mitra
Replies
25
Views
924

### Closed: Re: Single conductor inside hollow conductor

I do not have any direct explanation but these come to the mind:

1. The two conductors are not symmetrically places. Because the shield is floating, a large part of the electric field is blocked...
22. ## Thread: Help with medication timer design

by c_mitra
Replies
5
Views
331

### Closed: Re: Help with medication timer design

Me too!

But my medicines do not come in bottles; they come in Al foil strips. And I need to take them at different times. All but one are to be taken once a day but I forget one or the other quite...
23. ## Thread: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transformer

by c_mitra
Replies
17
Views
757

### Closed: Re: 1 minute vs 1 second isolation voltage test for isolated offline SMPS transform

You forgot to mention the frequency.

This is basically a test for the dielectric. Some certification agencies require the isolation test.

The voltage must be ramped slowly (else your test will...
24. ## Thread: Single conductor inside hollow conductor

by c_mitra
Replies
25
Views
924

### Closed: Re: Single conductor inside hollow conductor

Potential is related to an electric field. There is nothing about "static" charge distribution: of course if the charges are moving, you get an electromagnetic radiation.

Electromagnetic...
25. ## Thread: Whats the best way to ESD damage a PCB

by c_mitra
Replies
6
Views
329

### Closed: Re: Whats the best way to ESD damage a PCB

Most of the components are sensitive (to ESD) before they are put in place. Once they are in the board, they are interconnected and are far more resistant to ESD.

Running up and down the stairs...
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