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    Help with voltage conversion

    Hi I am creating a project with the new arduino due and I need to convert the voltage output (0.55v to 2.75v) from the DAC into a range that is linear from -5v to +5v I have looked through national semi app note 31 and in the upper right corner of page 6 there is a circuit for voltage...
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    Help with a Tube EQ circuit

    Hi, I have been given a circuit diagram of a tube based EQ unit and I need some help if anyone could help me I'd be gratefull. Basically the circuit is in two parts a Tube base amplification stage and a "passive" inductor based EQ circuit that "appears to me" to be in the feedback path of the...
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    hv transformer wiring

    hero, thanks very much, even
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    hv transformer wiring

    Thanks hero, I've been working with hv dc ozone up until now so sorry for the confusion, just so I'm clear could you check my wiring diagram? Thanks, even
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    hv transformer wiring

    thanks hero, one question, does it matter which wire of the secondary is grounded? there are no markings on the secondary wires at all, and they are both the same colour. am I correct in thinking one secondary wire is + and one - that should be grounded? if so how would I identify which is +...
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    hv transformer wiring

    My current thinking is to wire the secondary to the electrode like the image attached, Since one side of the secondary is contained within a sealed pyrex tube I am presuming this is correct but I would appreciate input/corrections, thanks.
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    hv transformer wiring

    hi, I am building an ozone generator using a high voltage neon sign transformer and I am a little unsure of wiring. The transformer I have is brand new and runs off 230v and produces 3kv@9ma. I want to be 100% sure of how to wire this safely for obvious reason so I would appreciate your...
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    JFET Mic Pre Advise Please

    "A mic preamp used an input transformer about 30 years ago but now they use an electronic circuit." Yea, I understand what you mean but there is a certain tonal advantage to using a transformer also, I see what you are saying about the impedance, adding a transformer would be wasting the high...
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    JFET Mic Pre Advise Please

    audioguru: "its input impedance is 10M ohms so why ruin it with an input transformer" I really need to make this ciruit balanced and add to add phantom power, which is why I thought of adding a transformer, is there another simple way of achieving these functions without the input transformer...
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    JFET Mic Pre Advise Please

    thanks again hero999, even
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    JFET Mic Pre Advise Please

    I think I may have been wrong with the output impedance values that I posted, basically the circuit (well two in series will make up the mic pre) will need to be suitable for connection to a line level mixer, after some more reading it seems as if "The impedance of the line input is high --...
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    JFET Mic Pre Advise Please

    so, if i understand what you're saying correctly I need to increase current through q4 such that it can drive the low impedance load but such that it is low enough so as it wont overheat. Is this correct? I have no idea how to go about running output impedance simulation, I am using multisim...
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    JFET Mic Pre Advise Please

    I know it has been a while since I posted on this circuit but I have been flat out with other projects until now, so, I have modified the circuit to include diodes between the base of Q4 and ground as you suggested and this has reduced the current to just below 6ma, I'm not sure how to...
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    JFET Mic Pre Advise Please

    thanks a lot for this i'm glad i have at least biased correctly and i will work on the current draw on Q4 and post updates as/if required, you've been a massive help cheers
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    JFET Mic Pre Advise Please

    im simulating with multisim 10 with a specific 2sk117gr model, which are the ones I have. some voltages of circuit in no signal condition Q1 drain voltage is around 17.3V. gate sits at 20.2mV source 133mV Q4 base 17.3V collector 36v emitter 16v Q3 base 7.5v collector 16v emitter 6.81v i've...
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    JFET Mic Pre Advise Please

    I thought you calculated current by the following: (I = Current/V=Voltage/R(t)=Resistance Total) I = V / R(t) I = 36/(8.5 + .060) I = 36/8.56 I = 4.2(mA) this is close to the value i'm measuring in the simulation also, so now i'm really confused.
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    JFET Mic Pre Advise Please

    "Why have you insisted on a non-standard value for R1" basically I am a little confused as to bias the fet correctly, my take on it from my reading was to aim for a figure close to the measured Idss of the measured device (gate and source connected and voltage applied with no signal) with a...
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    JFET Mic Pre Advise Please

    "I'm not sure if you understood when I talked about E96 and E24 values" oh i understood ok, just wondering whether metal film E24 values are superior to carbon E24 values in terms of noise. "You have sketched a class-A heater.." haha, might be usefull its freezing here in ireland ok, heres...
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    JFET Mic Pre Advise Please

    "What does the xlr grounding pin do?" Not sure to be brutally honest, I'll have to look into this, although it is on almost every preamp schematic that I have seen so far. "What load is the pre-amplifier driving?" Hmmm........well it will be driving a professional line level sound card...
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    JFET Mic Pre Advise Please

    "think Mr Evengravy records electric guitars so he likes the even harmonics distortion caused by Jfets and vacuum tubes. He also likes overdrive but not the severe clipping distortion produced by opamps. " pretty much spot on, the pre will have DI input for guitar plus a transformer to allow...
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