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About Kerrowman

  • Birthday 05/30/1962

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  1. 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.
  2. 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?
  3. 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’?
  4. 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 there is some significant resistance from the meter. In practice it looks like this: In the two photos, first I have have some jumper leads plugged in and the circuit runs normally. Plug in the meter instead and, while there is some current flowing, there is not enough for the system to function properly. As I understand it the ammeter should offer minimal resistance to the circuit and so should not interfere with it during it’s measurement process. Using another meter, when disconnected, the resistance of the red plug through to the black plug via the meter set to 'A' is 0.1 Ohms. I do have a clamp meter but I am expecting to use a desktop digital meter that will take readings automatically at regular intervals without my having to remember to stop and take one. Am I doing something wrong here and how can I obtain a good reading without interfering with the circuit's operation? Thanks
  5. 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 price, but it doesn't appear to work with laptops, only desktop computers. The link for this is here: https://www.radioworld.co.uk/cba_iv_pro_58250-1015-computerized_battery_analyzer?ref=StoreYa&utm_source=stry&utm_medium=trafb&utm_term=pla-296303633664&utm_campaign=storeya51 What I am measuring is the effect on the charging process for some small 7Ah AGM batteries, but later also regular car batteries, of a generator that produces high current pulses from a capacitive discharge circuit. So what I would like to be able to do are the following: 1: Release a known amount of charge (Ah) or energy (Watt-mins) from a fully charged battery; so acting as an electronic load 2: Observe the charging profile of the battery with a Volts vs time graph on a laptop as it is being charged by my pulsing system 3: Be able to measure the power and current delivered to the battery being charged So I don't need the device to be a power supply but instead to monitor what is happening as the battery charges and also to be a load at times. I have looked at a few devices (see below) but while they can clearly act as loads, I'm not so sure about the other requirements? ET5410 Professional DC Electronic Load Programmable Digital Control Battery Capacity Tester Electronic Loads 400W 150V 40A Measurement & Analysis Instruments from Tools on banggood https://banggood.onelink.me/zMT7/s4nr3ceq DL24/P 150W/180W 2.4" DC USB Tester Electronic Load 18650 Car Battery Capacity Monitor Discharge Charge Power Meter Checker https://a.aliexpress.com/_vdYJ8j Thank you
  6. 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. 😬
  7. 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.
  8. Is it relevant that each coil has a ferrite core? That certainly changes the B flux at the centre of each one.
  9. 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 on Instagram under the name: ‘kerrow_wood_turning’
  10. 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 not an IP160R099) to produce its 1,000V back EMF pulses at 100-5kHz using the 555 based internal trigger system or the rotor/Hall based system where it will reach a pulse repetition frequency of about 200Hz. The graphic shows the Hall sensor option but the Trigger circuit has the timer option built in at the flick of a switch. This is all to investigate the behaviour of high voltage transients on batteries and is what Nicola Tesla was doing in the later stages of his life when he researched the ‘fluid-like properties’ of electricity in its longitudinal wave format. I and many others think that there are still unrecognised qualities of electrostatic fields and electricity itself that may allow us to harvest electricity from the environment. Certainly, others seem to have done so and in the inductive methodology of science, my work on this is to see if I can replicate an observable phenomenon. If I get statistically significant results then I will do a paper on it and share it freely, and also how to build it for further replication, and leave it to others in the future to theorise what might be going on. Even though I’m a physicist by training, my brain isn’t young enough anymore to do the maths and algebra The next stage is to add a ‘capacitor dump’ circuit that collects the HV pulses and discharges high current pulses to the batteries and which will enhance the effect. If any of this interests you then I’m happy to share the info as I go along. Anyway, all that aside, I have measured one of my coils at 380mH so let’s assume they are all the same, and there are 5 in parallel. I’d be interested to see what your simulation shows and presumably any suggestions for how to tweak the back EMF up a bit further. Thanks Jules
  11. 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 coil has a resistance of about 10Ohms from memory and there are 5 in parallel (see pic). My maximum current using the 555 trigger is about 1.75A. When using the rotor based hall sensor then about 0.6A (surprisingly, but this value is very dependent on the positioning of the Hall sensor - as with the ignition timing on an ICE).
  12. 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
  13. 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?
  14. Thanks I will look into the links. Am I right in thinking the diode would have its anode towards the FET?
  15. 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 shut off times and so produce higher voltage spikes. Going from a circuit that didn't use a driver chip to one that does has increased the voltage from about 800V to 1,040V as shown in the scope image using a 10:1 voltage divider. I have read that there are ways to further reduce the FET shut off time but as electronics is not my main discipline I find them rather confusing. For example, reducing the Gate bias resistor (R5) further (to 5R?) or putting a small capacitor (1nF?) across R5 and keeping the PCB track resistance from R5 to the Gate of Q2 as short as possible. I would appreciate any suggestions. Thanks
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