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  1. CommanderLake

    Create controlled 50v pulse

    I doubt the static resistance of the wire would make much difference to the rise time and just testing 2 bits of wire thick and thin with my Keysight U1733C LCR meter, the thicker wire of precisely the same length has a much higher inductance and impedance at 100KHz, also thicker wire would risk...
  2. CommanderLake

    Create controlled 50v pulse

    I replaced all the wiring with 22 AWG solid core and made it as short as physically possible, this is the photodiode circuit: thats a polymer capacitor I fashioned a ground pin for the scope probe out of a piece of thick bare copper wire wrapped around the tip and crammed into the breadboard so...
  3. CommanderLake

    Create controlled 50v pulse

    Thanks, I had to get another breadboard because the MOSFET switching causes so much kickback I couldn't get a clean measurement. You can still see a small spike on the graph there with a completely separate breadboard and bench supply for the photo-diode, I increased the resolution enhancement...
  4. CommanderLake

    Create controlled 50v pulse

    I got some fast photo diodes to accurately measure the rise and fall times of the led and finally got around to getting a reading and its faster than I thought: That's a 3.7μs 10-90% rise time and a 1.5μs 90-10% fall time.
  5. CommanderLake

    MPS MP4008 PCB design

    Given up on the AL3353 because I cant figure out what should be on the COMP pin and it requires bigger shunts decreasing efficiency. I reduced the size a lot by replacing the output capacitor with a couple of 100uF ceramics and using the main heatsink for the diode next to the MOSFET with...
  6. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    I wrote a little C# program to help with the confuzling equations and now I can work out the value of RSL on page 8 of the AL3353 datasheet. However, there is no mention in the datasheet of how to work out C2 on the COMP pin.
  7. CommanderLake

    MPS MP4008 PCB design

    I've learned a lot more about boost converters and MOSFET's and redesigned the board at least twice since this one, I'm replacing the MP4008 with a Diodes Incorporated AL3353, see this post...
  8. CommanderLake

    MPS MP4008 PCB design

    Thread obsolete.
  9. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    So I've been learning about and improving all aspects of the boost converter, I recently had an epiphany learning about how MOSFETs turn on and off and how to simulate and estimate switching losses and how to select the most efficient one for the application. I used my 100MHz (1GHz sample rate)...
  10. CommanderLake

    Canon EOS 6D hot shoe to 5v logic trigger

    Sorry posted too early, I just found out the hot shoe is a switch that closes to trigger the flash.
  11. CommanderLake

    Canon EOS 6D hot shoe to 5v logic trigger

    Not sure where this thread should go so please move it if required. I'm trying to use the hot shoe of a Canon EOS 6D to trigger a 5v logic circuit for a Picaxe but the pulse from the camera is triangular with a width of about 130nS and a peak of about 950mV which is too small to amplify with...
  12. CommanderLake

    MPS MP4008 PCB design

    I've been designing a PCB for an MP4008 driven LED controller to power a CMA3090-0000-000Q0U0A40G from a car (approximately 13.5-14.5v) to 3.6A at up to 50V and was wondering if there are any experts here who could take a look at my design and point out any possible issues. I use DipTrace, the...
  13. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    I've decided to get an OPA196 and use this circuit: It will allow 10:1 current regulation and has the advantage of redundant potentiometers in case one has a problem while minimizing the load on the OPA196 output to maximize its rail to rail output capability for use with a single supply. One...
  14. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    How's this for inspiration: A friend visited with his Mavic pro.
  15. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    Still trying to interpret your message but it would still need current regulation given sufficient battery voltage.
  16. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    Have you simulated the dimming circuit in the EV4008 datasheet? The dimming mosfet with a capacitor on the gate is allowed to drift into its linear region increasing heat dissipation. Garry seems to think my idea will work and I need to be able to fine tune the current limit so the LED is not...
  17. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    I dont want to use PWM dimming because the circuit looks inefficient and requires many extra components so I had the idea of amplifying the feedback signal with an op-amp and using a pot to adjust it like this: But there are so many op-amps to choose from, how do I choose the best one for my...
  18. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    I finally have the solution: Hi David Sorry this has taken a while but I now have an answer. The RLED_AC figure is the AC impedance of the LED which typically is 10-15% of the resistance you calculate by using VLED/ILED. I have also attached a spreadsheet which we have which calculates the...
  19. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    At last I got their attention, this is the reply: Hi David, Thank you for your web enquiry. Our FAE (Gary Church – in copy) agrees with your findings and is working with the designers to fix the problem. Gary will advise ASAP. Kind Regards Eric. Eric Spooner Business Development Manager...
  20. CommanderLake

    Car power to constant current 3.6A 50v boost converter

    Just tested powering the led using my bench supply and a Sinergex puresine 350w inverter and it takes 340w into the inverter to power the led to 144(3.2A) of its maximum 172w(3.6A), thats a pathetic 42.3% efficiency!
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