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  1. duke37

    Woo-Woo Free Energy From Pulsed DC Transformer

    Switch mode power supplies use this principle, you can get an efficiency of 80% or if you are very good 90%. You cannot get a COP of greater than 1, there are always losses.
  2. duke37

    Reversing polarity

    BISTABLE My scanner has gone into a sulk. You can do this with a pair of NOR gates 4001 or a pair of NAND gates 4011 or a 555. The 555 may be prefered since it might be more robust. Connect p2 to 12v via 10k. Connect p4 to 12v via 10k Output p3. One relay will be connected to ground and the...
  3. duke37

    Woo-Woo Free Energy From Pulsed DC Transformer

    Flanders and Swan "Its entropy man"
  4. duke37

    Voltages - continuation of the discussion

    Dear dorke, you seem to make unwarranted assumptions. I did not take it to LTspice since I had experience with it in other applications and know that floating nodes are not accepted. Harald has described how LTspice can be made to accept them by adding a varying voltage giving an AC component...
  5. duke37

    Hartung amplifier project

    The glow in the valves comes from the filaments which are fed from the thick 6.3V winding. White/red. Do not confuse with the 110V (red) thin winding. The valve filament connections are pins 7 and 8 in both cases. You can check for a connection through the valve before connecting the transformer...
  6. duke37

    Voltages - continuation of the discussion

    I have used LTspice to simulate audio filters and discriminators, also RF filters and replacement components to eliminate the dropper resistor in AC/DC valve radios. The last job I did was to find the value of the gimmic capacitor for top coupling an IF transformer. Why do you need to know...
  7. duke37

    Why does a dc motor "stutter"

    I have never used stepper motor but this sounds as if it is one. You can probably find the steps/turn by energising one winding with a steady current and counting the number of 'cogs'.
  8. duke37

    Voltages - continuation of the discussion

    I can solve the problem in #14 with an AC input but cannot do it without initial conditions, resistance or other current input. LTspice is much cleverer than I but it cannot solve it, it just goes into a sulk. Ratch My feet are not shown in the circuit but I often put my foot in it.:) What were...
  9. duke37

    Voltages - continuation of the discussion

    The problem is not properly specified. The voltage source is 20V not 12V, not that it makes any difference to the problem. No switch is shown so it is not clear what the initial conditions are. There is plenty of ionisation here if I skuff my feet over the nylon carpet.
  10. duke37

    SCR S838

    When I used a SCR to drive my coil winder, I connected the heat sink to the positive supply .
  11. duke37

    Voltages - continuation of the discussion

    So, you would start with no voltage on any capacitor and then input a step voltage change. In other words, an AC component would be added to the voltage source. This is not shown in the diagram. In practise, the voltages will be dependant on resistance leakages and the ionisation of the air.
  12. duke37

    Voltages - continuation of the discussion

    I do not understand the question. Why should there be any voltage when the DC is blocked by C1?
  13. duke37

    SCR S838

    The centre leg is not needed if the tag is the same connection. Clipping it off saves a little in assembly. Theis does not work of course if the body is isolated.
  14. duke37

    Hartung amplifier project

    I have had a look at the transformer. 1.Inner connection marked with a black tag. 2.Next connection plain white wire. 3.Next connection marked wth a black tag. 4.Last connection plain white wire. Connecting 2 to 3 and putting mains into the150V winding gives 200V or so on the primary...
  15. duke37

    Lead acid battery - how long can it be left discharged?

    A lead/acid battery contains sulphuric acid which combines to the plates when discharged. After time, this lead suphate becomes stabilised and is more difficult to dissociate into lead and sulphuric acid so capacity is lost. I do not think it matters how the battery is discharged. Keep the...
  16. duke37

    What polarity is this?

    I have known them as a pooner or Birmingham screwdiver:).
  17. duke37

    Need help with relay circuit

    You can make a bistable with a pair of 4001 gates or 4011 gates. You will then need a couple of transistors to supply the relay current or to switch the load directly.
  18. duke37

    What polarity is this?

    If you have a big enough hammer to get inside, there will probably be an electrolytic capacitor connected to the power socket. This will tell you the polarity
  19. duke37

    How to connect wires to prongs on switches?

    Or solder. However, if you use solder, make sure that no flux gets up into the switch or the contact will be poor.
  20. duke37

    LED setup help needed.

    Sorry about that, I just read "one comes on after another". The 4017 could still do the job with a few diodes to activate lower leds.
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