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Posts posted by keron

  1. I am here with this DAC design with PCM1704 and the standard circuit provided by BB. As you can see in their datasheet.(Page 9)
    But I do not think they did justice with the DAC chip by throwing a simple post DAC filter in the Typical application circuit >:(. But I understand it is for 8x Oversampling topology and should work just fine.
    My case is a bit different by going for NOS(non oversampling ) in fact more complicated since I do want to play back CD material through the DAC which samples at 44.1Khz.
    The standard filter recommendation is a Bessel filter of 3rd order or higher for oversampling topology, but for NOS .............
    I am not sure
    I am not clear about which filter topology to use too. But my understanding is the phase linearity is as important as the cut off Frequency. I have few CD DAC circuits that start filtering at 40Khz.
    I know the the first ALias will appear at 22.5KHZ but I do not want to start my -3dB slop much before it. Do not want introduce Phase non linearity with a filter which will possibly ruin the NOS effect.
    Can someone help me?

  2. Hi,
    I was recapping my cambridge audio Azur 640p (hypnotoad mode)with bipolar capacitors as the initial change. Everything went fine. Then I changed the 100uf capacitors near the regulator ICs as the second step.Everything worked fine for few minutes then no sound from any channels. I looked again and again for polarity change with the 100 uf electrolytics I changed and any issues with regulators.Regulator output is 18.5 +/- volt.
    No click heard from relays.After a long day and thoughts I decided to take off the relay.I was not easy. so I have to break it with a small plyer and take it out in parts. The D7 across relay terminals(please see attached circuit) reading 18.5 volt to 20 v using my DMM.The relay is rated for 5 volt. 20 volt across the D7 which essentially is the relay driver voltage bothers me.
    Any ideas ?....



  3. Hi all,
    I came across the advertisement about Pangea P-100 powersupply for cambridge audio 640P phonostage. The manufacturer claims that it make the DACs/phonostages sounds better by incorporating a LOW-PASS filter at 12VAC output from this PSU.It also has DC supply but it is the AC out that the manufacturer claim about.It is about 100USD in Amazon. I am planning to DIY if there is any such possibility of a better powersupply excist.
    The PSU that comes with this phonoamp is only 12 VAC ,500mAmp.Many claims using higher current rated powersource made this phonostage sound better.Is it possible at least in theory?I donot want to spend half of what I paid for the device, to buy a PSU if its not going to change anything.
    This PSU is getting really hot during operation so I doubt the phonostage is making the PSU to struggle meeting its demands ;D!

  4. Hi all,
    I am looking for a circuit that operates in 9-12 DC and will generate voltage in 2-3KV range with negiligible current. I came across many designs but interested if anyone knows any circuit that uses common step down transformer with primary and secondary reversed as the first step in conversion.I am planning to use Cockcroft–Walton multiplier to increase the voltage from transformer. Flyback transformers are difficult to find /not familar for me to use.But would defenitely consider if its readily available
    I came across this circuit and like to know if something similar can be tried with a step down transformer


    If anyone know any schematic with small flyback transformers I would be glad to try.I am only concerened about availability.
    The whole purpose is to make a negative ion generator to clean dust from my vinyls. I donot want to use the ones based on Pizo electric but somehing that will generate a massive negative ion flow that will neutralize all sticky dust on my LPs
    .The prime consideration is making it as small as possible.

  5.                               i have a better circuit zombie,  for water level monitoring .please search for "water level monitor for pumps" in the forum posted by myself...and practicaly it is not possible to fabricate screw driver like things for electrode.how will u connect wires to it dude....
                                if u use dc signal it will corrode anyway.i am saying this from experience .i used stainless steel.but in two months the positive elctrode thinned out.
                              the circuit i posted is not a level detector.its a fullwave opamp rectifier,and it is possible to use AC signal for detection,only thing is iam not sure about how it is implemented in my water level controller using logic gates......

  6. i found out the problem finally.it was not the circuit.it is perfect.the probe was defective.it was made of paper clips .it got corroded and made electrical contact through the mixture of rust and the glue i used to fix it.i changed into a brass electrode and a silicone adhesive.now i guess no problem.thank you all for scraching your brain with me for finding a solution.any one with a better idea for probes.????
    how to modify this for my use...

  7. ok if i use a 500k resistor through which i connect a NPN transistor as a switch to the output pin it should work fine rt?
                                    i think the powersupply is also a problem.i get shock from the neutral wire in my home.can it be a reason for my logic gate malfunctioning.when i touched the tip of soldering iron when the circuit was working it made the relay to switch on.what to do to make a good powersupply?rt now iam using a 12 volt fullwave rectfier and 1000uf capacitor .out put regulated through 9 volt regulator ic.when i test it somewhere it work fine.any solution to make a proper ground..

  8. the modification is i have used red and green LED S in my first diagram.i have not used them in the original circuit.it was only in the theory part i used the LED.WHEN I USED IN MY REAL CIRCUIT NOW .The  circuit  malfunctioned.please see the diagram.there is some serious problem with the current schematic.i havent used the LED in my original working circuit.when i used  there is severe problemsin the circuit.no idea what is the problem.


  9. in the same  circuit please someone tell me(
    why there is a 1Mohm resistor with 1uF cap inbetween the logic gates ,also the 47k and 10nF cap.please ?
                                    what they are for and are they necesaary for normal functioning?if they are not there what can happen?

  10. i have made some modification in the circuit.i am using two Metal oxide varistors .one for protecting relay terminals from arcing and the second protects the entrie circuit.
                                i have also included green and red LED as in diagram.they are connected from pins shown through a 330ohm resistor.
                                       also grounded the 12 volt supply rail through 330uF(electrolytic) and 0.1uF as in this pic
                             now iam facing two critical problems.one the green LED  remain on most of the time on switching on the supply to circuit  regardless of water level.after that circuit is not working properly.you can say not pumping at all.it has become entirely non functional.but sometimes in between testing it works properly.should i use a transistor switch than directly connecting the out from 4001 AND 4011 to LED through a resistor?
                                             as i said before iam using a transistor  comon collector circuit with only 100k resistor across base to amplify signal from probes.what can be the problem,any idea?                                           
                                                 in the same  circuit please someone tell me(http://www.zen22142.zen.co.uk/Circuits/Alarm/water_lev_alm.htm)why there is a 1Mohm resistor with 1uF cap inbetween the logic gates ,also the 47k and 10nF cap.please ?

  11. Hello Ante,
                            can you please explain a  lil more?if any circuits drawing  availabe for this purpose?please help.
                                         iam panning to build a mains voltage multiplier using Cockcroft-Walton  multiplier.
                                              so in order to have ion flow u need to have ground near the high voltage terminal.please see the link i posted.
                                             what about making a positve and negative voltage  multiplier and using it instead of using a ground and  high negative  voltage.

  12. please see this circuit.
    in the first part of the description about making an ioniser /ozoniser,just above the pic of close-up view showing the emitter and tube, and also the neon output level indicator. you can read like this.

    The connections between the sections of voltage multiplier are just thin hookup wire, since the potential between stages is relatively low at a few hundred volts. The output goes via the usual safety resistor/s and also passes through a neon and capacitor based current flow indicator as used on the ioniser page. The final output is on three needles pointing at three short tubes made from brass eyelets soldered to self adhesive copper tape. The tubes are all conected to mains neutral via a few safety resistors.
                                                        suppose i use a two pin plug and i accidently changed from live and neutral,it will be really hazardous.any methods to prevent it?

  13. hello guys ,
                           you are deviating from the topic.i have used a MOV for the sparking issue.its nota problem at all.but what about my question on pulldown resistors  please explain .do i need to use them in every  input of logic gates.even in case of output of a logic gate used as input to another.please explain

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