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Recent content by smuel

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    Increase common mode range of INAMP??

    Hi, Just wondering if anyone knows of a nice little circuit to decrease the common mode voltage at the input to a differential instrumentation amp? I'm using the AD8555, currently working ok with a common DC level of up to about 6V. Problem is I need to measure power consumption etc on a 12V...
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    Digital trace over analog ground region

    Hi, I have a question regarding a mixed signal PCB design. I have a board with partitioned ground planes (AGND and DGND) but there is an analog IC that requires a digital control signal from the CPU that cannot be physically positioned on or near the analog/digital border. So basically I have...
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    Lithium Thynol Chloride battery issues

    thynol Hi All, Not sure if I'm in the right part of the board here... I was wondering if any of you have experience with Lithium Thynol Chloride cells? I'm having endless dramas with reliability, possibly due to passivation. I am preconditioning the cells according to the datasheet (Tekcell...
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    Controlled impedance routing in Altium Designer

    routing corners Thanks for the reply. I still cant seem to get this rule working though... Here's a more detailed description of the steps Ive taken. I have placed a ground plane on the bottom layer, and an adjacent plane on the top layer. I used place>polygon pour, and connected them both to...
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    Controlled impedance routing in Altium Designer

    controlled impedance calculator no ground plane Hi, I'm wanting to tune the impedance of some tracks in a layout that is already complete. I have tried turning on 'characteristic impedance driven width' in routing rules, but no matter which parameters I change here or in the layer stack...
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    Parallel RLC circuit conversion

    Thanks for the replies. I think i've got it sorted.. I found the admittance of the parallel circuit, then simply found the related impedance Z=1/Y, then as far as i can tell, the real component of this impedance is my series resistance for the series equivalent. What do you think? Anyway, we...
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    Parallel RLC circuit conversion

    Hi, I need to convert a high frequency inductor model from a parallel RLC circuit (all three elements in parallel) to a series RL in parallel with a capacitor. I know the resonant frequency will be the same, so for a given inductance the capacitance will be the same, but i'm guessing the...
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    Rounded corners in Protel???

    Hi, I want to route a pcb with rounded corners in Altium Designer 6 (new version of protel) and i cant seem to find any way to do it apart from using arcs... I have tried selecting 'rounded' in the corner section of the design rules, but it does nothing. This is driving me crazy!! Any ideas...
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    Any Induction Loop Geeks?

    Hi, If i was to play a guitar, take the output signal, then feed it back into the pickups via and induction loop system what would happen? I'm thinking there will probably be a huge amount of nasty feedback, but could this be tamed to provide sustain or controlled feedback? I mean, could the...
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    Identifying old transformer

    Ok, ill try to hack into it (stripped screw holding me back) and see if i can figure out which is the primary. I still dont get what you mean by the 4 wire thing... Once i figure out which side is the primary, how do i connect the 4 wires to mains?? Thanks, Sam
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    Identifying old transformer

    Hi, I bought an old transformer at a garage sale a while ago and was wondering if you guys might be able to help me figure out what it is. It is pretty big, about 15x15cm. The only markings are... 10-1222-A NTK 230454 On one side there are 2 blue wires and 2 grey. On the other side there...
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    LOHET1 current sensor problem

    Hi, I'm using a hall effect current sensor IC mounted in a current transformer to measure AC current via a micro. It is supposed to output an AC voltage proportional to the AC current sensed. This is all working fine, but i noticed something quite strange... The output waveform is exactly...
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    Solution to oscillating preamp issue

    Hi, I've built a guitar amp using the schematics on this site **broken link removed** It is mostly working fine, but when i flick the 'bright' switch, the opamp goes into oscillation. I've bypassed both power pins to ground with 0.1uF ceramics, and I've tried it with the power amp...
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    Low frequency oscillation problem in opamp

    Re: oscillating opamp Thanks everyone for the advice. It turned out to be coming from the virtual ground. I stuck a 0.1uF cap from earth to virtual ground, and a 56pF cap across the 22k feedback resistor, and now it is working perfectly. Opamps are much simpler on paper.. Thanks again, Sam
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    Low frequency oscillation problem in opamp

    Re: oscillating opamp Yep, I've got the input biased at 4.5V. It's a 9V battery supply, with 2x680k resistors dividing it for the input. I have used a seperate 4.5V bias for the feedback virtual ground. I spoke to one of my lecturers and he suggested sticking a small cap from the virtual...

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