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audioguru

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  1. Like
    audioguru got a reaction from Tornado17 in 0-30V Stabilized Power Supply   
    Why do you show an LT1038? it is obsolete and is not made anymore.
    It is impossible for it to dissipate 32V x 10A= 320W. Its datasheet shows that with a huge heatsink with fan or with liquid nitrogen for cooling it can dissipate only 120W. Its control circuit gives 10A only when its input to output is a few volts and cuts the max current to 2.5A when the input to output is 30V.
  2. Like
    audioguru got a reaction from Aokane in LED panel .   
    I cannot see which connects to what. Can you provide a schematic?
  3. Like
    audioguru got a reaction from jonythunder in 0-30 Vdc Stabilized Power Supply   
    The original circuit should work fine up to 15V at 1A if you replace the old opamps with the newer higher voltage ones. You probably should recalculate the resistors that set the maximum voltage and current outputs. If the Chinese kit uses the transistor that shorts the opamp output when the power is turned off then the resistors that feed the transistor need to be recalculated for the reduced voltage.
    I have used perforated stripboard for many projects including very complicated ones. The copper strips are cut to length with a drill-bit and become almost half the wiring of a pcb. The parts and a few short jumper wires become the remainder of the wiring. Only one wire is in each hole so changing a part is easy like on a pcb.
  4. Thanks
    audioguru got a reaction from Mate_Well in 0-30 Vdc Stabilized Power Supply   
    Did you know that Chinese companies (ebay, Aliexpress, Banggood, Amazon and others) have copied the original defective Greek kit and used the wrong opamps and resistors that burn up? Their kits of the original project are very cheap. They use some Oriental transistors instead of the original ones.
      
  5. Thanks
    audioguru got a reaction from Mate_Well in 0-30 Vdc Stabilized Power Supply   
    The original project used a 24VAC transformer and TL081 opamps that have a maximum allowed supply of 36V. Since the project was not able to produce 30VDC at 3A because the supply voltage was too low, I changed the transformer to 28VAC and changed the opamps to TLE2141 that have a maximum allowed supply of 44VDC.
    Please post a video of your TLE2141 opamps blowing up if you power them from the 66VDC produced from rectifying the 48VAC from your wrong transformer. Or just parallel the two 24VAC secondaries which produces a rectified 32VDC so that the maximum regulated output from the project will be about 25VDC at 3A.
    The TLE2141 U2 gets warm, not hot because its output current is fairly low since it drives the driver transistor Q2 that drives the output transistors to 3A.   
  6. Thanks
    audioguru got a reaction from Mate_Well in 0-30 Vdc Stabilized Power Supply   
    One 2N3055 transistor overheats in the original circuit that used a 24VAC transformer and produces 25VDC at 3A. Therefore I used higher voltage opamps, a 28V 4.2A transformer, a more modern driver transistor Q2 that can be cooled well and two 2N3055 transistors to share the heat on a very large heatsink. Some people added a fan and a smaller heatsink instead of a huge heatsink.
    If you connect the two 24V windings of your transformer in series and use the centertap as 0V then its output voltage will be 24VAC x 1.414= 34V minus the 1V for the two rectifiers then the supply voltage will be too low because the circuit needs a 28VAC transformer. 
    Your transformer voltage is too high so it cannot be used for this project. Or you could parallel the two 24VAC windings or with the centertap as above then the maximum regulated output voltage will be 25VDC at 3A.
  7. Thanks
    audioguru got a reaction from Mate_Well in 0-30 Vdc Stabilized Power Supply   
    The 24VAC transformer has an output voltage too low for this power supply to produce 30VDC at 3A. The regulation will fail and there will be lots of ripple in the output at and above about 25V at 3A. I recommended a 28VAC or 30VAC transformer and higher voltage opamps years ago.
    For an output up to 5A then the transformer max output current should be 7A or more, the main filter capacitor C1 value should be about 17000uF or more, there should be 3 output transistors each with its own emitter resistor, a larger heatsink for the output transistors and change the value of R7 from 0.47 ohms to 0.27 ohms.
     
    I finished making improvements on this project in July, 2014 but others have made more changes.
  8. Like
    audioguru got a reaction from Mate_Well in 0-30 Vdc Stabilized Power Supply   
    The TIP31 is 83 times slower than the BD139 that I recommend that has almost the same speed as the original 2N2219 that got too hot as Q2. Then the TIP31 will probably cause oscillation. 
  9. Like
    audioguru got a reaction from soldertools1 in Power supply   
    You forgot to say if the 10V output from your power supply must be AC or DC. You also forgot to say if the input is AC or DC and its voltage and frequency.
    Did you know that the output power from your power supply will be 10V x 1000A= 10000 Watts? Where will it come from? What will it be used for?
  10. Like
    audioguru got a reaction from HaddyS in High Voltage low amperage   
    10,000V at 0.02A is 200W which is a lot of power for a little power supply.
  11. Like
    audioguru got a reaction from HaddyS in battery level indicator   
    The LM3914 in a DIP case is not made anymore. Buy them before they are all gone.
  12. Thanks
    audioguru got a reaction from HaddyS in 0-30 Vdc Stabilized Power Supply   
    The original defective circuit had many overloaded parts that will blow up. The improved version fixes it.
    Opamp U3 senses the output current in R7 and reduces the output voltage and output current to match the current set with P2. The maximum output current is 3.0A in the improved circuit and the two output transistors have a total maximum current rating of 30A so they will not blow up with only 3.0A. 
  13. Confused
    audioguru got a reaction from PhillipGok in Surround Sound for car audio   
    The Hafler opamp circuit should do what you want.
    The New Japan Radio IC datasheet doesn't explain what it does. It has graphs showing bass-frequencies-only, some phase-shift amounts and its block diagram shows a subtraction circuit for both channels but doesn't show what is subtracted.
  14. Like
    audioguru got a reaction from electron234 in 0-30 Vdc Stabilized Power Supply   
    I use copper wire, not rice wire. They put rice in everything they make, especially batteries.
  15. Thanks
    audioguru got a reaction from soldertools1 in acid_circuit   
    Why are you using an old fashioned vented lead-acid battery? Most circuits today are powered by rechargeable Ni-MH or Lithium batteries that have no acid.  
  16. Like
    audioguru got a reaction from electron234 in A modern day 0 - 30V, 0 - 3A Linear Power Supply?   
    The ebay kit that is a copy of the original faulty Greek power supply on this site is also sold by Banggood and Amazon. Banggood is selling it at a clearance price since they probably had many complaints. They have modified it a little and are selling it again as a kit with a 28V/2A rating and an LCD meter for it.
     
    The very nice looking 30V/10A power supply is extremely cheap. Its ad has no detailed spec's. It does not even say if the voltage and current are regulated.
    If something looks to be too good then it probably is not true.
  17. Thanks
    audioguru got a reaction from HaddyS in 0-30 Vdc Stabilized Power Supply   
    Since it was years ago I do not remember which page of which thread has version 6 or 7. I have the schematic and parts list of version 6 here:


  18. Like
    audioguru got a reaction from Jordan&tiffany in Electronic Gun !!!!!!!!!   
    Hi Shantanu,
    Electrolytic capacitors have a vent on top to slowly release gasses that build up when the capacitor is connected with backwards polarity then has a high current.
    With a very high current, the vent cannot release the gasses slowly so the capacitor explodes.

    A 9V battery cannot provide a very high current. Maybe a battery made with series-connected AA Ni-Cad or Ni-MH cells would provide enough current for a backwards electrolytic capacitor to explode. Bad-smelling "fluff" comes out.
  19. Like
    audioguru got a reaction from teprojects1 in How to find electronic parts?   
    I buy electronic parts from Digikey and Newark because they have offices and warehouses in my country and they stock everything.
    What can't you find?
  20. Like
    audioguru got a reaction from Lee Ross in 0-30 Vdc Stabilized Power Supply   
    February 23 above on this page has the latest schematic of the revised 3A lab power supply.
  21. Like
    audioguru got a reaction from Robert Wise in 0-30 Vdc Stabilized Power Supply   
    February 23 above on this page has the latest schematic of the revised 3A lab power supply.
  22. Like
    audioguru got a reaction from KP99 in What's the difference between MC14046B and CD4046?   
    About 53 years ago the CD4046A was introduced but it had many problems. It was replaced a few years later by the improved CD4046B and MC4046B and HEF4046B.
    Your CD4046A must be one of the very old ones with problems.
    Look on the datasheets of an A and of a B to see the differences.
  23. Like
    audioguru got a reaction from joeydennis11 in LM3914 pspice library   
    Hi Maliki,
    National Semi doesn't have a spicy ( ;D) model for their LM3914.
    I looked on Google for Spice and then Pspice Model For LM3914 and found many people asking for a model too. One guy found a similar model to pspice online at a university.
    There are many French links. Parlez vous francais? Not me, and I hate Google's horrible translator. ;D
  24. Like
    audioguru got a reaction from joeydennis11 in c828 transistor   
    It is probably an Oriental 2SC828 transistor. Go to www.datasheetarchive.com to see its spec's and to see substitution guides.
  25. Like
    audioguru got a reaction from FranceRouze in diy 2.1 pc speaker   
    The TDA2003 does not bridge well because the output offset voltage are not matched for the two amplifiers like a monolithic bridged amplifier IC. But you might be lucky so try it.

    With a 14.4V supply the bridged output at clipping into 4 ohms is 14 watts.
    If your speakers are 8 ohms then the power is 8 Watts.
    If the supply voltage is less than 14.4V then the power is less.

    You should make an active crossover circuit.
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