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  1. drillz

    Heatsink temperature may ruin resistors?

    Hi LionelHutz we have taken your advise and now have two heatsinks. Thankyou for all.
  2. drillz

    Heatsink temperature may ruin resistors?

    Hi, Thankyou for getting back. I'll investigate shortly ...but for now, i've again been told that this set-up is going to be OK, despite having raised my concerns.
  3. drillz

    Op-Amp circuit with input referenced to other ground.

    Dear Readers, I am designing phase loss detection circuitry for the input 3-phase supply for an electric drive. This circuitry must simply do the following…. 1. Detect when all three input phases are present 2. Detect when one input phase has been lost 3. Detect when two input phases...
  4. drillz

    isolated MOSFET gate driver problem

    Dear Engineers, I am currently making an offline flyback SMPS. It uses two MOSFETs in the primary circuit and so I need an isolated gate drive. Here is my investigative attempt thus far. Unfortunately, the output is only 0 to 7V instead of the required 0 to 16V. I would be very grateful...
  5. drillz

    Heatsink temperature may ruin resistors?

    Hello Thankyou for your replies. Please may I now be specific as you raise interesting points of concern. I’m certain I divulge nothing confidential here as its just a resistive load. The real set-up is 300R of resistance. This comprises four parallel pairs of 150R resistors. These resistors...
  6. drillz

    Heatsink temperature may ruin resistors?

    I have thick film planar resistors dissipating 2KW. They are mounted on a heatsink with thermal resistance = 0.144 degree C/watt. The resistor datasheet says that if the heatsink gets above 210 degrees C then the resistors can handle zero percent of their rated power. (Each resistor can handle...
  7. drillz

    LED Lightbulb

    Hi, The idea of putting zeners across series sections of LEDs was shown to me by the Senior Electronic Engineer at a fairly large lighting company. (-they make warning beacons etc). This was at an interview. He asked me what the zeners were for and i said to stabilise voltage....he then replied...
  8. drillz

    LED Lightbulb

    Hi, I used to test LED lighting products at work and the problem is, as you say, that they are too dim...or rather, they are bright but only in the "zenith" direction.......to get them spraying light around more you end up having to use too opaque diffusers. I once switched a nine Watt LED...
  9. drillz

    Drives at motor's starting up

    the only problem with start-up, is that of burning out the windings due to the fact that a stationary motor is not yet generating enough back-EMF to "reduce" the supply current. I would get a current clamp round the motor supply and see how much it gets up to with slowly increasing start-up times.
  10. drillz

    Video amplifier Test Procedure query.

    I must apologise......the attenuator after the signal generator cuts the input signal (to the amplifier) down to 100mV peak to peak....not 2V peak to peak as first described. (i unfortunately got mixed up.....the 2V peak to peak signal is what is measured at the output of the signal generator...
  11. drillz

    Converter

    I think that these rotary type converters are like kind_of_motors with the three sets of windings spaced around the rotor to give the three phases.........since its a mechanical device, and since the rotor may not always spin at constant speed -also since the physical spacing of the phase...
  12. drillz

    Video amplifier Test Procedure query.

    Thankyou all for these valuable replies. VE1BLL....i am having doubts about the use of the attenuator myself, as well as the 30 minute "warm-up". melone....Unfortunately the design engineer works elsewhere usually. He is very busy and i could not ask him something unless i was absolutely...
  13. drillz

    Video amplifier Test Procedure query.

    I would be very grateful for help on the test procedure for a video amplifier that my company makes. I am sure my company will not be harmed by me anonymously posting a link to a brief-ish form of the schematic here, as its only simple inverting stages and an analog multiplier IC...
  14. drillz

    Push-pull SMPS with half-wave secondary.

    Hi, I am definetley sure it's push-pull....here is a very rough diagram of it.... The TL598 PWM controller IC, with pins 13 and 14 connected, is specially made for push-pull circuits. http://www.ortodoxism.ro/datasheets2/9/0oguit27jufq3wdyw7f9gyuo7lyy.pdf Even more interesting is the fact...
  15. drillz

    Constant current source

    In line with what VE1BLL said....here is a circuit for a current mirror.... http://en.wikipedia.org/wiki/Current_mirror The current mirror will give you constant current of any value set by the "so called programming resistor".
  16. drillz

    Laplace Tranformation

    I've got a super-easy book on it if you want to know how to use it quick (will dig it out to get title if you are interested). -However, if you are into doing a doctorate on it then unfortunately i can't help. (I once remember working in a power electronics company and had to double pulse a...
  17. drillz

    Liquid Level Sensor

    You could try http://www.sensor-systems.com ..they do this and the website can give some ideas.
  18. drillz

    Push-pull SMPS with half-wave secondary.

    I am actually just a contractor at this workplace and don't actually know what equipment it will supply. I thought it was quite a special case as Push-Pull SMPS is almost always used with a full-wave rectified secondary. I know the engineers at this place are far more highly expert than...
  19. drillz

    Push-pull SMPS with half-wave secondary.

    Dear Readers, I have recently been testing a push-pull SMPS with isolated secondary...except the secondary has only half-wave (as oppose to full-wave) rectification. (That is, it just uses one diode.) The feedback coil also has only half-wave rectification. This SMPS uses TL598 PWM controller...
  20. drillz

    MOSFET gate discharge circuitry.

    Hi, I am driving an N-Type MOSFET in an offline flyback SMPS. At the moment , the drive circuit is as follows... However, I believe that the gate capacitance must have a discharge path to ground to make the MOSFET switch quicker...therefore, i have dreamed up the following circuit.... I...

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