Search results

  1. duke37

    400 Hertz at 120 V

    Why will a 60Hz transformer not work well on 400Hz? There will be some additional core loss but unlikely to be serious.
  2. duke37

    Diodes

    If you are changing the type then watch the thread, they may be unf or metric. Get with nuts and washers that fit.
  3. duke37

    Diodes

    Diodes of this style are made in both polarities often with the same number but one polarity has a R added. So be careful you get it right. 600V 20A diodes should be readily available, Depending on the reason for failier, you could use stronger diodes.
  4. duke37

    Kustom double barrel guitar amp help

    I see two diodes next to J8. There will be two more, possibly 1N400x. Disconnect both red leads Measure resistance across each diode in both directions You will get some conduction in the forward direction a nd matbe some conduction in the reverse direction depending on the rest of the circuit...
  5. duke37

    Connecting non-solderable wires

    There will be temperature errors if the junction is not at a uniform temperature. We used compensation cable (copper/constantan?) to extend the couple by several meters and this worked well. The cold junction was at the measuring meter/computer. The main problem was making a neat thermocouple...
  6. duke37

    Kustom double barrel guitar amp help

    Since there is a 7815 (positive) and 7915 (negative) regulator, there will be a full wave bridge rectifier. It will take only a few minutes to check for a shorted diode. This can be done without desoldering. Logically work from input to output.
  7. duke37

    Kustom double barrel guitar amp help

    The fuse in the transformer is in the secondary and you said that the fuse in the power plug was failing. Which is it? I am not familiar with US mains supply fusing. I have used the wrong term before, I should have used regulators, not stabilisers.:) Nice picture.
  8. duke37

    Kustom double barrel guitar amp help

    'How did you determine that the reservoir capacitors are fine?' Did you measure capacitance, ESR and leakage at working voltage? I have never looked at the impedance of the transformer but if the lamp limiter lights with no load, then there is a shorted turn. You can get plug in power meters...
  9. duke37

    Kustom double barrel guitar amp help

    The classic way to investivate this type of fault is to use a lamp limiter. A 40W bulb in series with the mains limits the current and so protects the fuses and allows measurements to be made. What is the rated power consumption and the fuse rating? The transformer should run OK with no load...
  10. duke37

    Connecting non-solderable wires

    I used to use chromel/alumel thermocouples, there could not be soldered with tin/lead solder so the ends were 'tinned' with silver solder (Easyflow) which would take normal solder very well.
  11. duke37

    welding pit

    I have bought items from China, described as welded when they mean soldered. Welding involves melting the two parts, with the possidility of a filler of similar material. Soldering involves adding a low temperature alloy to join the pieces. The workpiece is not melted but it may be slightly...
  12. duke37

    welding pit

    Do you mean a soldering bath? Welding means that the components are melted at the join. See stick, Mig, Tig. The resistance wire must be electricaly insulated from the pot. How will you do this? Perhps a cooker element under the pot would work.
  13. duke37

    My electronics workshop

    I didn't see a coil winder or a lump hammer for gentle repairs.
  14. duke37

    I need a switch that's switches from primary power to secondary if primary shuts off....

    There is no indication that it is anything to do with the mains, If it is an emergency generator then the changeover needs approval. It could be a 12V supply for a model railway or a 24V supply for railway station slave clocks. As is often the case, we are kept in the dark, particularly if rhere...
  15. duke37

    I need a switch that's switches from primary power to secondary if primary shuts off....

    Seems like a changeover relay with the coil connected to the main supply would do. When this fails, the relay will drop out and the power can be taken from the auxilliary supply.
  16. duke37

    advantage and disadvatnge of AC to DC converter circuit

    Any energy that you put in to drive the fan will need to be extracted by the fridge, So use as little as possible.Even a very low air movement will increase the heat transfer coefficient considerably.
  17. duke37

    Placement of Ammeter in Active LM338 Regulator

    For this application you do not need any accuracy of better than 5%. I do not think that moving the circuit parts around will affect tne accuracy greatly. The LM317 has a limit of 1A but can be increased with a pnp boost transistor. Alternatively change to a 3A LM338.
  18. duke37

    Placement of Ammeter in Active LM338 Regulator

    It would be nice to know what the current will be and what accuracy you want. A better circuit would be the B circuit with the voltage sense connected to the output. You should look up the requirements for stabilising capacitors.
  19. duke37

    advantage and disadvatnge of AC to DC converter circuit

    Tough:( Also, you cannot use two capacitors in series to use a higher voltage since one capacitor may take most of the voltage and the other very little. The normal solution is to put a potential divider to the midpoint. I made a large power supply with two capacitors in series and two...
  20. duke37

    Placement of Ammeter in Active LM338 Regulator

    The two circuits are slightly different. A measures the current taken by the load and by the LM338 B measures the load current only. The volmeter could be connected to the output for more accuracy. The sense resistors will probably only be passing 5mA or so, they are not specified.
Top