Announcement

Collapse
No announcement yet.

Common Ground Switch(Generator Mode) & Adding a Generator Coil - Observations

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Hi Gary,

    In the process of learning about the SG and its components I just watched some tutorials regarding diodes. Before that, I was under the illusion that as long as voltage/amperage rating where more or less the same you can interchange one diode with the other. But I learned that different diodes behave very different under certain circumstances, I have some questions regarding diodes which I hope you can help me with:

    A single 1N4007 will probably blow as the current will exceed it's one amp rating. I use two 1N5408 diodes twisted together in parallel, and they handle the current just fine.
    I assume that putting a couple of 1N4007 in parallel would do the trick as well? Or is the 1N5408 so similar in characteristics to the1N4007 that they can be interchanged?


    The D3 diode of the comparator circuit (12V zener, 1N5242) I could only find in packages of 250. So at the moment of ordering I looked for a diode with similar specs, available in smaller quantities and ordered this one:
    Nexperia BZX79-B12,113
    https://nl.rs-online.com/web/p/zener-diodes/0508163/
    spec sheet: https://docs.rs-online.com/13a2/0900766b80b4c56e.pdf
    I was wondering if you have any idea if I can replace the 1N5242 with the zener diode I bought without running into any trouble?


    Many thanks in advance,
    Rodolphe


    ​​ Diodes question.png
    Attached Files
    Last edited by pearldragon; 05-01-2020, 06:30 AM.

    Comment


    • #17
      Hi Rodolphe,

      I assume that putting a couple of 1N4007 in parallel would do the trick as well? Or is the 1N5408 so similar in characteristics to the1N4007 that they can be interchanged?
      The 1n5408 and 1n4008 are both common diodes rated at 1000 volts PIV (peak inverse volts), however the maximum foward current rating of the 1n4007 is only 1 amp as opposed to the 6 amp current rating of the 1n5408. Switching speeds and foward voltage drop are about the same for both. So two 1n4007 in parallel could safely handle up to 2 amps and two 1n5408 in parallel can safely handle up to 12 amps. I had both on hand and went for a little over kill.

      An ultra-fast switching diode here would be desirable. Two UF4007 diodes in parallel would be able to handle up to 2 amps, and a MUR3020WT would be able to handle up to 30 amps.

      The Nexperia BZX79-B12,113 zener should work just fine. This is only used as a voltage reference and is rated the same as the 1n5242 in both wattage (500 mw) and zener current (20ma max, 10ma typical).

      Gary Hammond,

      Comment


      • #18
        Hi Gary,

        UF Diodes
        An ultra-fast switching diode here would be desirable. Two UF4007 diodes in parallel would be able to handle up to 2 amps, and a MUR3020WT would be able to handle up to 30 amps.
        Could you maybe explain me in a bit more detail how using one of these UF diodes would yield better results? Is there a specific reason why you did not use them yourself? Or did you wanted to stick to the handbooks first before interchanging parts?


        Power rating (variable) resistance
        I’m planning to do some of my own measurements on the efficiency of single/double pulsing area/rpms. To do that I want to build in some form of the “trigger switch”, as mentioned on page16/17 of the Advanced Handbook. But reading those pages and comparing them with the Intermediate Handbook page 9, got me confused a bit for the following reasons:
        -In the Intermediate Handbook page 9 a potmeter is mentioned of 1W.
        -In the Advanced Handbook page 16 a potmeter is mentioned of 25W, replacing the 12-Ohm 10W resistor(s).

        Since up to this point I’m still working with my potmeter* from the Intermediate Handbook without any problems, I assume the 12-Ohms resistors didn’t need to be 10W, and neither is there a reason for using a 25W potmeter if a 1W is sufficient? If correct, I assume that the 10W resistors / 25W potmeter are just what they had lying around when doing the Advanced Manual tests.

        I’m asking this since I was in doubt whether I will make a switch to completely bypass my potmeter, or use a low resistance fixed resistor (so I can toggle between this fixed resistor and the potmeter) and started to doubt the wattage of this fixed resistor because of the above mentioned.


        *my potmeter currently is a 200 Ohm, 2W, 3%, 10 turns.

        Many Thanks in advance,
        Best regards,
        Rodolphe

        Comment


        • #19
          Hi Rodolphe,

          Could you maybe explain me in a bit more detail how using one of these UF diodes would yield better results? Is there a specific reason why you did not use them yourself? Or did you wanted to stick to the handbooks first before interchanging parts?
          This was a generalization and may not really matter at this particular location in the circuit. You can also eliminate the diode altogether for fastest charging if the secondary is only 6/10 volt less than the primary at the start. The two batteries are essentially in parallel with each other and will equalize voltage between the two through the power coil ....... minus the forward voltage drop across the charging diodes. If the extra diode is added, the combined forward voltage drop is 1.2 volts and allows for charging a secondary battery that is 1.2 volts lower than the primary without voltage equalization taking place. But equalization isn't all bad, because it results in faster charging of the secondary. And once the secondary battery voltage exceeds that of the primary the current draw falls off any way.

          Peter Lindemann has pointed out that the ultra fast diodes attached to the collector/power coil junction deliver a higher voltage and faster charging to the secondary battery than the slower speed diodes. The slower speed diodes (1N4007), however, kick back more energy to the primary battery resulting in less current draw and a longer run time. So it is sort of a trade off and up to you which way you want to go. Faster charging of the secondary vs longer run time from the primary battery.

          Peter also demonstrated what an ultra fast diode added to the battery swapping circuit in his "Beyond The Advanced Handbook" presentation does. It caused the radiant energy to manifest at all points in the circuit causing the neons across the transistors to light up brightly! The volt meters across the batteries were glitching and sometimes going off scale! Of course this was operating at 24 volts and not the usual 12 volts everyone starts out with.

          I did use a MUR3020WT ultra fast diode in the attraction motor I made, and it charges the secondary very fast. I also used a UF4007 in the SSG driving the two-stage mechanical oscillator my grandson and I built. It also charges pretty fast. But I didn't want to go back and change out all the diodes in the other SSGs that I already had built previously.

          Since up to this point I’m still working with my potmeter* from the Intermediate Handbook without any problems, I assume the 12-Ohms resistors didn’t need to be 10W, and neither is there a reason for using a 25W potmeter if a 1W is sufficient?
          I use a 100 ohm, 25 watt, single turn potmeter in all my builds now. I've burned out a few low wattage pots, so I tend to go for a little overkill with them.

          Gary Hammond,

          Comment


          • #20
            Hi Gary,

            Thanks for your explanation regarding the workings of the different diodes. I haven't looked at the "Beyond The Advanced Handbook" yet, but i did bought it already.

            I use a 100 ohm, 25 watt, single turn potmeter in all my builds now. I've burned out a few low wattage pots, so I tend to go for a little overkill with them.
            Ok, thanks. I guess since my 2W potmeter hasn't burned out yet, any fixed resister with at least a 2W rating should be good (and if not, I'll find out pretty quick too ).

            Thanks!
            Regards,
            Rodolphe

            Comment

            Working...
            X