EEWeb Forum

Can anyone tell me how can I get 1.2V @ 15A Output?

2013-06-17T09:46:57-07:00

Category: Power
Tagged: low-power

Question:

I want to make a circuit which receive 12V or 9V input (from a computer charger e.g.) and give 1.2 V (like a Nihm battery) @ 15A. I was told i could use a LM317 to regulate voltage, but i need more informationt. Any help? thanks.

calculate inductance of 12V relay coil

2013-06-17T05:04:45-07:00

Category: Analog
Tagged: Relay coil Inductance

Question:

How to calculate inductance of 12V relay coil if only coil resistance is known?

dc motor runs too fast

2013-06-17T04:30:00-07:00

Category: General
Tagged: dc motors

Question:

On my troubleshooting chart its says if your motor is running too fast it might be that you have made improper connections. What do they mean by improper connections?

PCB factory

2013-06-16T17:58:36-07:00

Category: Digital ICs
Tagged: CMOS

Question:

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Power Converter Canonical Model - Solving Example

2013-06-16T00:04:32-07:00

Category: Power
Tagged: power, converter, canonical, model

Question:

Hello,
I am an EE student and have some problem with understanding canonical model (from Erickson book, picture attached). It contains averaged switching circuit (“DC transformer”), effective output filter (L and C), and sources that represents PWM response for output voltage error.

The problem is – how can I use it to compute output impedance or Gvd(s) and Gvg(s) transfer functions? Does j(s) source even matter (it’s connected parallel to voltage and their are both “ideal”). Isn’t output impedance just LC circuit output impedance? I guess I make some elementary mistake, and I’d really appreciate some step-by-step solution (no calculations of course, just what are essential parts of this analysis and what is related to another thing).

Feel free to ask me any questions, I’m looking forward to any answer.

100W Audio Amplifier w/ Mic Input

2013-06-15T22:33:30-07:00

Category: Analog
Tagged: audio apmlifier, audio, 100Watts, 100W, transistor, sound, music, noise, mic input, microphone

Question:

I want to make my own audio amplifier with the specs of

100Watts , (stereo) 50Wmono 50WSstereo
mic input
equalizer (bass mid treble) (high mid low)
Transistorized ( i must not use IC chips)
maybe 20khz-20khz. (i dont know, what can you suggest best?)

i have no idea how to start it, can anybody help me with it, im not an engineer yet. i just want to make my own amp. ^_ . it would be helpful if you can send me an schematic diagram and other useful stuffs. thanks in advance. :)

voice command

2013-06-14T22:54:08-07:00

Category: Electromechanical
Tagged: ic

Question:

can anybody help me a circuit that accepts voice command.

Footprints for Pads

2013-06-14T01:08:57-07:00

Category: Digital ICs
Tagged: design

Question:

In making pads to a certain IC would you actually follow the IPC standards? and what if the manufacturers have their own unique standards like different pitches?

How to troubleshoot resistors and capacitors in circuit?

2013-06-13T23:25:05-07:00

Category: Passives
Tagged: Circuit troubleshooting

Question:

I recently purchased a vintage Hammond A-100 organ, which is based on tubes, no solid state (imagine that!), the ‘percussion’ feature (inside pre-amp) does not work so I ordered a new set of tubes thinking that it would solve the problem, well, it didn’t, so now I need to do a more in-depth troubleshooting to find out what’s wrong, reading online I found a lot of people replacing resistors and capacitors due to their age, in order for me to test a resistor or a capacitor, do I really need to disconnect it from the circuit, are there any ‘tricks’ someone in the field is aware of? It sounds like a daunting job since there are hundreds of them in this beast. I’m also probably gonna have to get creative because I only have a multimeter. thanks.

how to get more pcb orders

2013-06-13T23:16:20-07:00

Category: General
Tagged: low poer

Question:

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Best regards
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Skype: ugeelara
MSN:ly792930977@live.cn

CCTV CAMERAS, WIRELESS OR WIRED- CCD OR CMOS?

2013-06-13T13:11:23-07:00

Category: General
Tagged: CCTV,CAMERA

Question:

If you are thinking of buying a cctv camera for the first time you could find the choice a little baffling. What lens to choose? CCD or CMOS? Wired or Wireless cctv ? 16mm to 3mm?

Enhanced Hall effect current sensors

2013-06-13T12:22:11-07:00

Category: sensors
Tagged: current sensor

Question:

Hello, guys I’m a PHD candidate working in a research lab. I’m working on my thesis while assisting the company to see if there is a market for a Hall effect sensor which has a higher switching frequency switching frequency >400 kHz vs the current 250 kHz, while maintaining a linearity of 0.1%.

My goal in contacting you is to see if there is a real or perceived need for such a device, based upon you or your colleagues’ industry knowledge, and if there is, what quantity might be required.

I will appreciate your opinion a lot.

About Measuring Sheet Resistance using van der pauw structure

2013-06-13T10:53:45-07:00

Category: Test & Measure
Tagged: Measurement, van der pauw structure, math, physics

Question:

Hi everyone,

As the figure and equation shows( picked from Marcel Pelgrom’s Nyquist A to D converter, page 27)

If we analyze it from physics, equation 2.22 is quite right because the radius r2 is greater than r1,

but if we calculate it by calculus( integration), we know that r1 shoule be the denominator and r2 should be the nominator, just the inverse as equation 2.22.

So can anyone show me how we should analyze the structure correctly? I’m quite confused.

Thanks!

Can anyone analyze how the High Frequency Pre-amphasize Circuit works？

2013-06-13T10:17:53-07:00

Category: Analog
Tagged: High Frequency, amplifier, feedback network, filter

Question:

As seen in the figure, can anyone analyze how the high frequency pre-amphasize circuit works, especially the part which is labeled in the figure? The signal goes through capacitor C2 forward or C2 is used as feedback path?

The R1 and C1 network is a high pass filter.

Thanks!

What produces Second Harmonic Current?

2013-06-13T09:41:25-07:00

Category: General
Tagged: Harmonics, harmonic current, 120 Hz, 3 Phase

Question:

Does anyone know what could produce 120 hz current on two legs of a 3 phase system? (120 hz is being produced on a and b phase, not c) We know that it’s not a drive misfiring and we know it isn’t a transformer saturating.

Details:
The service entrance transformer is a Wye – Grounded Wye winding configuration. The load bus is commercial facility, nothing out of the ordinary. One hint is that we only see elevated levels of the 2nd harmonic current on two of the three phases; with an average of 8% Distortion level as expressed as percentage of the fundamental, with fundamental current measuring an average of 100 amps. This is measured at 480V; at the clients main switchboard.

This was measured over a two day period; and I am beginning to question whether or not a recent client lighting retrofit with high efficiency ballast might be the source; whereas they do have some drives, these are not energized during the predominant period of measurement; but when AC Drive is online and working, approximately 15 minutes out of two days profile, it provided slightly higher 2nd order current as well. I scoped the drives, there is no problem with pulse firing sequences; as that was the first place I looked given historically having seen 2nd order current produced by a misfiring SCR on a six pulse drive. But that is not the case here.

Thank you for your help, any feedback would be much appreciated!!!!
-Ashley

dc.generator starting

2013-06-13T09:32:38-07:00

Category: General
Tagged: dc genrator

Question:

Why if the output of a DC generator is shorted it will not build up?

Diodes in different ways

2013-06-12T23:38:36-07:00

Category: Test & Measure
Tagged: diodes

Question:

For testing purposes correct me if I’m wrong. I would say a transistor could be a diode by short circuiting the base and the collector of a transistor and now using its two terminals as two terminals of PN junction diode. So maybe by logic a diode could do the same, right? And my question is how would they differ in performance and reliability as a diode and as a transistor ?

troubleshooting dc machines

2013-06-11T16:45:22-07:00

Category: General
Tagged: dc electrical machine sparking at brushes

Question:

My book says that if your dc machine’s commutator brush sparks its caused by commutation windings defective. I dont understand what they mean by commutation windings defective.

open diode bridge rectifiers

2013-06-11T15:04:36-07:00

Category: General
Tagged: electrical, bridge rectifier, diode

Question:

When 1 of the 4 diodes of a bridge rectifier opens what happens to the following?

1) The output voltage?
2) The ripple voltage?
3) The ripple frequency?

Also how can you measure the ripple frequency to determine if a diode were open in a bridge rectifier circuit?

RUNNING LIGHT SEQUENTIAL CONTROLER KIT

2013-06-11T14:39:11-07:00

Category: General
Tagged: HELP TO COMPLEAT MY EXPm, PROJECT.

Question:

I WOULD LIKE TO ORDER a 12v ELECTRONIC RELAY KIT FOR MY EXPERIMENTAL PROJECT THAT CAN SWITCH A 10 TO 20 LIGHTS, WITH ON-ON-ON AND THEN ALL OFF,THEN RESTART. WITH A SPEED REGULATOR NOB.
CAN ANY BODY OUT THERE HELP ME TO ORDER ?
.(JavaScript must be enabled to view this email address)
REGARDS STEVOM-HOLLAND.

I JUST BUILT A HAPPY BIRTHDAY 12v LED SIGN EN WOULD LIKE IT TO FOLLOW IN SEQUENCE, LIKE ( 1.HA—2.PPY—3.BIRTH—4. DAY— 5.TO. — 6.U………..THEN AUTO RESET. VIEW THIS VIDEO. https://www.facebook.com/video/video.php?v=590036511016737&saved

Signal distortion combining simple op amp circuits

2013-06-11T09:13:16-07:00

Category: Analog
Tagged: AD826, opamp, distortion, stages

Question:

I’m currently having issues with an AD826 amplifier circuit I’m breadboarding. Attached is the circuit diagram of the circuit I’ve built. The circuit is decoupled with 1 uF and 0.01 uF capacitors at each stage. The feedback resistance should not exceed 1 kΩ, and thus I’ve used 1 kΩ feedback resistors in each stage. Each stage works correctly when hooked up individually. My input is a 50 Ω function generator output set to 150 kHz and about 1 mVp-p. With this simple circuit, using 4 stages, I’m fine. The signal looks clean and it’s amplified correctly. However, when I add a 5th stage, I get some distortion that I can’t seem to debug. Both responses are shown in attachments. I’m wondering if I’m missing something very fundamental about this chip’s operation.

I’ve tried switching the AD826 out with LF353 (slightly lower GBP and not quite desirable for this application). The 5 stage circuit works just fine, but if I add another I get a similar distortion. I’ve also tried changing power supplies, function generators, etc. I am convinced that there is something about these chips that I’m just not grasping.

Any and all advice is much appreciated.

free energy DIY

2013-06-11T08:56:40-07:00

Category:

Question:

i want to lean how to build free energy

Is this possible for simulation?

2013-06-10T22:51:05-07:00

Category: Test & Measure
Tagged: Circuit Simulation

Question:

For testing purpose in a circuit simulation software is it possible to generate a result for a hanging circuit? please see my attachment for better explanation.

You can also see my link:
http://www.partsim.com/simulator/#12162

Thanks

How do I accept and interpret handshake data from a 3D television?

2013-06-10T11:39:50-07:00

Category: General
Tagged: 3D, embedded, HDMI, TV, HDTV

Question:

I am developing a small device that will send stereoscopic video frames to a 3D-enabled HDTV with data from two analog video inputs, but I cannot find anyone (or even anyone who knows someone) who knows how the handshake data are formatted that pass between, say, an HDTV that supports active-shutter 3D frame display and a modern gaming console. In fact I don’t even know where to begin to look for such information. The rest of the project is basically complete, including the microcontroller for the HDMI connection (which yet remains un-programmed). We just need to understand how to send the output to the display.

If anyone has experience or knows someone who has experience regarding this subject, please respond. Blindly snooping this data and experimenting with them seems like a waste of time, as does sifting through the unnumbered U.S. patents with “3D” in the title.

Thank you so much in advance for any clues or advice!

Automotive Rain/Light Sensor IC

2013-06-10T07:41:47-07:00

Category: Embedded
Tagged: application

Question:

I would like to assemble/design the Automotive Rain/Light Sensor using your IC. How can you help me ?