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    Gigahertz current amplifier?

    "low noise" as in i need to amplify something in the order of "pA" in the background level of "nA"... i would be amplifying a pulse with width in the nanoseconds range, i would guess most of the frequency component are in the high range, so I may be able to withstand a amplifier which is bad at...
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    Gigahertz current amplifier?

    Does anyone know how to build a low noise current amplifer that has wide bandwidth from ~10Hz to ~1Ghz, and together with high sensitivity (can amplify ~nA/pA) I need one for my project to amplify photocurrent, but am struggling to find any suitable products or design guides... cheers
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    Atomic gas and Semiconductor Lasers.

    semiconductor lasers can be much more efficient because of direct band gap materials. From memory the efficiency of semoconductor lasers is at least 100x better than gas lasers...but the downside of it is it can not handle too high power..or the PN junction will breakdown..
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    Designing a timing device.

    Thanks Proton, but I looked through mcmaster, the timing relays are in the range of second~hours while I need a delay in the order of milliseconds. Secondly I think I don't need a timing "relay". I want to control my relay with a time delay device.
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    Designing a timing device.

    Hi guys, Background: There are 2 relays, A and B that needs to be controlled (24V) And a signal generating device that composes of a push button and an adjustable mechanism for timing delay between the 2 signals. (this is what I want to design) Specification: I want to design a...
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    Transformer Magnetizing Reactance

    In the case of an open-circuit test of transformer, when I increase the supply voltage, i realize the magnetising reactance (Xm) decreases, why does this happen?
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    Led Control

    A photodiode generates current due to the light intensity that it senses, maybe u can try it.
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    How to build a signal alternater

    Thanks for the suggestions
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    How to build a signal alternater

    Suppose I have 2 input signals V1 and V2, And I want my output signal to alternate from V1 to V2 and so on at a particular frequency. Any idea what components can help me to achieve this goal?? Thank you
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    Help on BJT question

    When using small signal analysis, the bypass capacitor shorts out midband, so emitter is grounded, also said by corneo in #6
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    Help on BJT question

    For the first simplification I used the Thevinin's Theorem. Looking at the circuit to left of base, the total resistance is paralleled RB1 and RB2 (To find thevinin's resistance ground the voltage supply i think), and then find the thevinin voltage. so..is it really wrong?
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    Understanding class A & B amplifiers

    I have read some texts myself but the explanations i read still leave me some queries. Below I have copied some text from wiki. From the text is in bold and my queries are in italic. Can someone please help me with my understanding, THANKS! Class A amplifiers are the usual means of...
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    Help on BJT question

    Thanks everyone. I have now tried to do this question again with your suggestions, please check my solution as attched.
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    Help on BJT question

    Thanks for the hint, this is wat i have done so far as implementing pi-model. The input resistance should be 33k//68k//R_pi (pi-model circuit attached) But how do i obtain the value for R_pi, is it possible to obtain it from the given data "current gain of transistor is 400"?? if not, why...
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    Help on BJT question

    Please view the attached circuit. I will be appreciated for any suggested answer, thanks! Q1) Calculate the dc input resistance of the transistor amplifier shown in figure 1 below if the current gain of the transistor is 400: I need some help on this one, i don't know the relationship...
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    Maxwell's Equation HELP

    thanks, this helped me to understand more.
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    Maxwell's Equation HELP

    Maxwell's Equation HELP! This is one of the Maxwell's Equations that I can't understand: \oint E.dl = -\int dB/dt .dS From what I understand, \intE.dl gives the potential difference along the line. Therefore \ointE.dl should always equal to zero because it is the potential difference of a...
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    Help on Electromagnetic Induction concept

    This is the material i read from textbook, and it doesn't make any sense to me! can somebody please help me out if they can understand the concept: To understand electromagnetic induction, we need to reconsider the concepts of electric and magnetic fields. A dc current I flowing through...
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