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  1. bertus

    PCB layout software?

    Hello, When you are using linux, there is a package called gEDA: http://www.geda-project.org/ It contains schematic capture and PCB design. They are busy to port the package to windows: http://www.delorie.com/pcb/geda-windows/ Bertus
  2. bertus

    Audio Marantz PM500

    Hello, When you say that there is a sharp transition 3-4 mm before the end, it sounds like a bad potentiometer.(the shift regulator). Bertus
  3. bertus

    How to design a transistor circuit that controls low-power devices

    Hello, The shown boards use the IFR520. That is a basic mosfet. What voltage levels are you using to drive the input of the board? Bertus
  4. bertus

    Datasheet wanted for Q165A diode

    Hello, I see more of those diodes on the back. Unfortunately the markings can not be read. I have used the pictures from this page to show: https://www.ebay.com/c/1271470258 What is the type number of the TV? Perhaps we can find a manual with more info. Bertus
  5. bertus

    Datasheet wanted for Q165A diode

    Hello, Is the Q165A written on the part or the board? I can not find anything for Q165A. Where is the part on the board. Bertus
  6. bertus

    How to design a transistor circuit that controls low-power devices

    Hello, If you want to use a mosfet, have a look at the IRL520. That is a logic gate fet, with a 10 A switching capability. Or have a look at the logic gate version of the mentioned IRFZ44, the IRLZ44. Bertus
  7. bertus

    Basic Pulse generation help

    Hello, If you want to keep the duty cycle constant over the frequency range, you could use a Hysteretic Oscillator with an 555: https://www.allaboutcircuits.com/textbook/experiments/chpt-8/555-hysteretic-oscillator/ Bertus
  8. bertus

    Audio Marantz PM500

    Hello, You are right, the resistors are indeed 47 Ohms. Both readings are off. 0,810K is 810 Ohms 0,L is open leads. I would replace bothe with the in the manual mentioned 100 Ohms resistors. Bertus
  9. bertus

    Frankenstein's Components.

    Hello, Some time ago I came accross "the maldivian arc welder": It seems to work: Bertus
  10. bertus

    Audio Marantz PM500

    Hello, Did you replace CF11? If so, did you measure the voltage on it? When the upper resistor ( RF09 in the schematic ) is broke, the voltage on it can be floating and causing the strange readings on the chips QF01 and QF02. Bertus
  11. bertus

    Audio Marantz PM500

    Hello, You say that on the pins 8 of the QF01 and QF02 is -13 Volts. The schematic states a value of +19 Volts. The value of -25 Volts on the emittor of Q801 is stated wrong, it should be +25 Volts. I see two 100 Ohms resistors between the +25 and +19, and -25 and -19 of QF01 and QF02. Are...
  12. bertus

    Basic Pulse generation help

    Hello, @twister , Next to the diagram it says 5 V/div. I see about 2.5 divisions, so 12.5 Vtt. Bertus
  13. bertus

    Basic Pulse generation help

    Hello, @twister , Did you look at the diagram in the openings post? I see that the signal amplitude is about 12 Volts. Bertus
  14. bertus

    Light bulbs as dummy load for Stereo ?

    Hello, As @WHONOES said, 80 mV is not that bad. If it changes, it could be a heating problem. Heat can make the setting go haywire. Bertus
  15. bertus

    Max Ratings L298N - V*A!=W?

    Hello, The saturation voltage is the voltage accross the output transistor, driving the motor. Bertus
  16. bertus

    Max Ratings L298N - V*A!=W?

    Hello, To dissipate 25 Watt, you will need decent heatsing as @davenn mentioned. Here is an article on heatsinks, based on the heat transfer on transistors: https://sound-au.com/heatsinks.htm You can even make heatsinks your self: https://sound-au.com/articles/diy-heatsink.htm Bertus
  17. bertus

    Max Ratings L298N - V*A!=W?

    Hello, First of all, the mentioned 50 Volts is the absolute maximum rating. One should never use a device on its absolute maximum value. The recommended maximum is 46 Volts. The device is a switching device and will never have the full powersupply on the end stage when it is driving 2 Amp. The...
  18. bertus

    CRT

    Hello, It sounds like you have choosen an resolution for the monitor that does not match the ranges of the monitor. Go back to the old settings and see if that solves the problem. Bertus
  19. bertus

    led 3w power supply ?

    Hello, Here is an article on heatsinks, based on the heat transfer on transistors: https://sound-au.com/heatsinks.htm You can even make heatsinks your self: https://sound-au.com/articles/diy-heatsink.htm Bertus
  20. bertus

    What happens if you put a BJT in a 12V AC circuit?

    Hello, You could try a solid state relays. On page 8 of the attached datasheet there are small pcb mount versions. Bertus
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