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  1. Kerrowman

    Using capacitors instead of batteries

    Hi Harry, Yes, 1/2 CV squared is a quick way to calculate the energy in a capacitor but there are three reasons why using a CBA is preferable and helpful, bedsides the fact that I already have one for the extensive Coefficient of Performance tests done over the past six months, as detailed in...
  2. Kerrowman

    Using capacitors instead of batteries

    Ok but if I’m using an electronic load to discharge the capacitor (so I can measure the energy it can deliver) once it’s been charged, then do I need the buffer of a DC-DC converter. Won’t the electronic load (https://www.westmountainradio.com/product_info.php?products_id=cba5) serve that function?
  3. Kerrowman

    Using capacitors instead of batteries

    Hi Harry, I hadn't realised that super capacitors were now so cheap and so I have come up with a plan to test the energy in and out as shown in the attached graphic. Am I right in thinking that after charging the capacitors, if I shorted the output terminals of the DC-DC converter that there...
  4. Kerrowman

    Using capacitors instead of batteries

    Hi Harry, Thanks for your thoughts. I think it’s only fair that I give you some context for my query.   For the last few years I have been researching and testing a hypothesis regarding energy harvesting using inductively generated HV transients. Here pulses are delivered to a battery and...
  5. Kerrowman

    Using capacitors instead of batteries

    Hi there, I would like to know if I can use a large capacitor to store energy on the way that I currently do with an 18Ah lithium battery?   My understanding is that with the minimal internal resistance of a capacitor, they can discharge their energy very fast even though the energy density is...
  6. Kerrowman

    Measuring circuit current

    Measurement accuracy is one issue yes but it does not explain why my device cannot function quite as normal when I’m measuring current with this meter compared to when it’s not in the circuit.
  7. Kerrowman

    Measuring circuit current

    The clamp meter gives about 1.1 so close to the analogue meter. The current here is steady and continuous and not pulsed. The DVM reads about 0.95 so there must be something in the DVM that is getting in the way?
  8. Kerrowman

    Measuring circuit current

    Interestingly, if I replace the DVM with an analogue meter it’s all fine. Do DVMs have other input components that can ‘get in the way’?
  9. Kerrowman

    Measuring circuit current

    Hi there,   I am trying to measure the current in a circuit by putting a digital ammeter inline, as in the diagram, after removing a connecting link that is also shown.   When the connector link is in, the circuit works fine but when the meter is in it doesn't work well at all, implying that...
  10. Kerrowman

    Computerised Battery Analyzer

    Hi there, I’m looking for a computerized battery analyzer that will achieve the functions shown below and show graphical plots on a Windows 11 laptop in real-time.   I have been looking at the CBA iV from West Mountain Radio that would have been fine and do all I need and at a reasonable...
  11. Kerrowman

    Circuit to increase CEMF spikes

    The link with Time is that V= L.dI/dt so the Voltage produced is determined by the rate of change of the current for a given Inductance. If 200kV is what is coming out of the simulator then something is not quite right with what’s going in to it, or an assumption somewhere. 😬
  12. Kerrowman

    Circuit to increase CEMF spikes

    What time is 0.38 h? I’m not sure what that means. The voltage at the main FET drain is definitely about 1,000V so I don’t know how you got 200kV.
  13. Kerrowman

    Circuit to increase CEMF spikes

    Is it relevant that each coil has a ferrite core? That certainly changes the B flux at the centre of each one.
  14. Kerrowman

    Circuit to increase CEMF spikes

    That’s fascinating but look at the spikes - 18kV. I don’t see that in practice, more about 1kV. Would it be helpful if I showed you the actual scope trace for the gate of the mosfet? Incidentally, I notice you do woodwork. I’m a wood turner and, if you’re interested, you can see some of my work...
  15. Kerrowman

    Circuit to increase CEMF spikes

    Hi Harry,   That’s good of you to suggest doing a simulation.   It will be useful to you to see a diagram depicting the whole circuit and the Hall sensor option (attached) so you can see how the trigger circuit relates to the whole.   As mentioned I can trigger the FET (FCP260N60E in fact and...
  16. Kerrowman

    Circuit to increase CEMF spikes

    The MOSFET is rated at 600V Vds and my D1 (1000V breakdown) is there to offer some protection (I think). So far the FET runs nice and cool and seemingly unperturbed. If you are referring to the pulse width from the 555 then they are 50% duty cycle pulses as often with a PWM setup. Each solenoid...
  17. Kerrowman

    Circuit to increase CEMF spikes

    It's part of the investigation to use pulses derived from an inductor field collapse. I have built what you suggest but it was for another application. Thanks
  18. Kerrowman

    Circuit to increase CEMF spikes

    So is the graph label ’Power Loss’ the back EMF at the drain?    And do you think any capacitance across the gate resistor would help?
  19. Kerrowman

    Circuit to increase CEMF spikes

    Thanks I will look into the links. Am I right in thinking the diode would have its anode towards the FET?
  20. Kerrowman

    Circuit to increase CEMF spikes

    I have built a circuit for which the aim is to produce high voltage back EMF spikes from the Drain of a MOSFET so I can investigate some of the properties of these voltage transients. What I have built is shown in the attached circuit where I am using an IR2121 driver chip to encourage shorter...
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