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Thread: Simpledrive versions

  1. #1

    Default Simpledrive versions

    I have been looking for a list of the different versions of the Simpledrive, and what the differences are between them. The best I could find was a post from 2 years ago in the B/S/T forum, but it only listed the I and II.

    I have one that I got on ebay several months ago. It's marked with "Simpledrive", "5Ar1", and what looks like a serial number. The main things I'm interested to find out are: What is the difference between this and the v4500, and are there known issues with startup spikes on the 5Ar1? (I have read about some other versions having those kind of problems.)

  2. #2

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    For today, 3 versions are relevant - v500/500mA v2500/2.5A and v4500/4.5A. 5Ar1 is the first revision of v4500.

    and are there known issues with startup spikes on the 5Ar1
    This is the case with some drivers released in 2014 (green pcb).

    BTW, this fall, I plan to stop producing universal "simpledrive" drivers and present several special drivers for use in laser show applications.

  3. #3

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    Mine is on a blue PCB. I have noticed a few things with this driver that have given me issues.

    I'm running it with PWM at 33kHz, and it shuts off below about duty cycle 7/255. For my application, it is important to be able to use the lowest duty cycles. I tested with a lower frequency (500Hz) and it turned on at 1/255. I guess a pulse width of about 0.7 microseconds is the limit of where it will turn on. Can you confirm whether that should be happening? It does say the modulation bandwidth is 100kHz, but I'm not sure if that means you can run pwm at a frequency up to 100kHz or if it can just switch at 100kHz. (100kHz 8-bit pwm would mean the shortest duty cycle has pulses that are 1/100k/255 sec = 39ns).

    I also noticed that when switching off power to the driver, it will momentarily increase the current to the laser diode before shutting off completely. It isn't a huge surge, because it hasn't killed any lasers yet, but if you were running close to the limit, maybe this could cause problems.

    The most problematic issue was that when testing, I found that if the modulation input is floating, a high current will be output to the diode. I have now killed 2 or 3 diodes by accident this way. I may test it more to find out whether it's just one of the + or - modulation lines that will cause this to happen. It would probably be a good thing to mention this in the instructions for the driver.
    Last edited by LeSabreTooth; 07-31-2017 at 10:24.

  4. #4

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    'm running it with PWM at 33kHz
    Yes, this driver has a rise/fall time of about 1.5-2ms. 100 KHz bandwidth is specified for the sine wave.

    This driver was conceived as a universal, for all occasions. Of course, if you need a fast speed, then you need something another. But 99% of users use it with slow PWM <10KHz and are quite happy with the result for 30 bucks driver.

    I also noticed that when switching off power to the driver, it will momentarily increase the current
    It shoul have no more than 10% variation of output specs in the range of supply voltages from 7 to 14 volts, + cut-off at 4 volts.

    The most problematic issue was that when testing, I found that if the modulation input is floating
    Not exactly that. In the floating state, the input has an impedance of about 10 KOhm, this is absolutely typical for similar drivers.

    Initially, for me it was a surprise that my drivers are buying for PWM driving. But in time I got used to it. Now I want to get away from universal drivers in the direction of special. One of them will very soon be ready for the final testing - it's a simple driver with a galvanically isolated "ttl" input (+start delay, powergood tracking and overtemp/overpolarity protetions). And it will be much faster than sipledrive. If you are ready to test it - I can send you one
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  5. #5

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    Quote Originally Posted by Bbe View Post
    Not exactly that. In the floating state, the input has an impedance of about 10 KOhm, this is absolutely typical for similar drivers.
    I don't think the input impedance would be an issue. I will test this more sometime and let you know more of what I'm seeing. What happened was I had a 5V source hooked up to the modulation input, and I was going to switch it to a 0V source, but to do that I unplugged the wires going into the mod input. At that time, the driver increased the current dramatically and killed the diode. It could be that when the + side is disconnected, the voltage on that line gets pulled up higher somehow. I did notice when testing with an analog mod input, that voltages above 5V continued to increase the output current.

    I'll PM you about testing the newer driver.

  6. #6

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    In this driver, the input is protected by a zener diode, even if you apply to it much more than 5 volts, you can't get a fatal current at the output. If you want I can read the I/O dependence curve. Anyway it's not more than + 20% to the normal value.

  7. #7

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    The prototype is almost ready, it remains to finish the firmware.
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