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Thread: The big TEC driver thread!

  1. #381
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    Am I right in thinking that the LD driver is a low side driver (more adequate for isolated cans) not a high side driver (cheap RED LOCS)?
    Yes it is a low side driver, and a very good one at that. I’m currently developing an equally good high side driver which will also be offered in combination with the TEC drivers later on.

    And we have one populated...But! As things appeared too good to be true, it turned out there were 4 capacitors missing on the parts order, didn’t notice the backordered note on the invoice, shit! Oh well, at least I can start debugging all accept for the TEC output and current limiting.

    Oh well… Stay tuned!

    Cheers!
    Attached Images Attached Images
    Last edited by Solarfire; 08-20-2011 at 11:32.

  2. #382
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    Quote Originally Posted by Solarfire View Post
    Yes it is a low side driver, and a very good one at that. I’m currently developing an equally good high side driver which will also be offered in combination with the TEC drivers later on.
    And we have one populated...But! As things appeared too good to be true, it turned out there were 4 capacitors missing on the parts order, didn’t notice the backordered note on the invoice, shit! Oh well, at least I can start debugging all accept for the TEC output and current limiting.
    Oh well… Stay tuned! Cheers!
    Ah ! thanks for clearing that up !

    Quite often back-orders only appear on the delivery advice note, and the only thing showing on the invoice is the "lack" of something .... which can be tricky to spot without checking the numbers!

    I for one am quite happy to wait till you have all the bits to finish it completely !

    Cheers

  3. #383

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    Sorry to ask it in here what the difference between a high side and a low side driver, whats the advantage or dis advantage between these two.

  4. #384
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    Quote Originally Posted by hivelaser View Post
    Sorry to ask it in here what the difference between a high side and a low side driver, whats the advantage or dis advantage between these two.
    A highside driver has a fixed zero volt connection and the positive connection changes voltage to push more or less current through the LD.
    A low side driver has a fixed positive connection and changes the negative voltage to pull more or less current through the LD.

    Some LDs have the negative connection common with the case (eg. cheap red 658nm LOCS from CD sleds) so you can use highside drivers without having to isolate their LD mounts from zero volt ground/chassis.

    Disregarding pedantic details and simplifying the situation a bit, it is reasonable to say that:
    Low side drivers have an advantage in that most electronic devices (transistors etc.) can sink/pull more current and modulate more quickly than they can drive (push/whatever).

    A cheap quad high side driver would be a great help for many hobbyists strapped for cash and I am currently waiting for a prototype of such a beast to arrive by post so that I can test it independently.
    If you are interested drop me a PM since this is a tad off subject for this thread.

    Hope that helps

    Cheers
    Last edited by catalanjo; 08-23-2011 at 19:45. Reason: push/pull & low/high

  5. #385
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    The main advantage of a high side driver is when you have common DVD diodes with minus at the case, so this can be grounded. For a low side driver the case is floating with regard to ground and thus must be isolated. And this creates a major hasard: the moment the diode mount is accidentally grounded the diode is blown. And this is just not a academic possibility, but happens all the time; just a little slip with the screwdriver when adjusting, and poof... I have heard many stories about dead diodes just for this reason; this includes dead Opnext HL6385s by members of this forum. With a high side driver these diodes would likely be still alive.

  6. #386
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    Quote Originally Posted by RedlumX View Post
    The main ......With a high side driver these diodes would likely be still alive.
    Only if multiple DVD diodes are always wired in parallel ...

    If wired in series it would require separate highside driver channel per diode since otherwise if wired in series ...kaput !

    Hence advantage of multichannel highside drivers for RED

    Cheers

  7. #387
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    A quick preliminary update:
    Dual/single TEC/LD-driver is up and running. Software (Embedded and GUI) are finished except for some cleanup and code straightening. Next week a pre-series run will be ordered for final evaluation and testing of board layout revisions. Three versions will be offered, Dual TEC-Driver with LD-Driver, Single TEC-Driver with LD-Driver, Single TEC-Driver.

    Features:
    Dual/single independent PID controlled TEC channels with low side LD-driver (high side version is in development).

    TEC channels;
    Separate Supply connections for each channel 12VDC/max 3500mA
    Output full bridge ±3000mA with no more than 200mV ripple @12VDC/250kHz @ 50% PWM duty cycle.
    Current sensing, user adjustable current limiting, auto calibrate on bootup.
    Over-temperature protection.
    Temperature range from 0.0C° - 30.0C°. Stability of up to ±0.05 C° depending on build.
    Controlled Fan outputs 12VDC max. 3000mA, temperature on/off range from 0.0C° - 30.0C°

    LD-driver;
    Type: Low side (high side version is coming)
    Supply: 6-24VDC/max5A (with standard 3W current-sense resistor), up to 15A with an external sense-resistor 10-25W. FET can dissipate 45W.
    Ultra linear up to 300+kHz on 1-20 Ohm loads.

    GUIs;
    Main, error-management and data logging.
    Individual activation/deactivation of the TEC-Driver channels A/B
    Individual activation/deactivation of the Fan-Driver channels A/B
    Monitoring of Temperature, TEC current, heating/cooling, H-Bridge Temperature flags, TEC current limiting, Laser diode current, Laser diode power via LaserBee II (Jerry hope you don’t mind) and PWM duty cycle.

    User adjustable parameters:
    All parameters except LD-Current and bias (next version LD-current and bias will be controlled via digital pots) are set via the Main GUI. Temperature, TEC Current limit, Invert heating/cooling, PID gains and windup limiting, Temperatures for fan on/off (next version PWM controlled), temperature tolerance for LD-Inhibit, temperature settling time for LD-Inhibit.
    All user adjustable parameters can be saved as presets to the integrated SQL database. No limit to the number of presets which can be saved.
    Service mode for manually setting output values.
    Error-management with error-text output. Errors a stored to EEPROM memory until acknowledged and cleared. Monitored are things like open circuit and short circuit of the thermistors, calibration fail, TEC-Temp. flags. Some errors will force shutdown like thermistor failure or exceeding of the user defined settling time.
    Individually user selectable data logging of all variables. Logged data can be saved to the integrated SQL database with export to Excel possibility. Adjustable sample rate from 10/s up to 5/h. Data accumulation can be monitored real-time on the integrated dynamic chart or in the Excel chart if opened before log begin.
    In the screen shots below you can see in the log file that the tested TEC has dramatically different efficiency’s what heating and cooling is concerned (cheap 30W China TEC) the rise and fall times (heating/cooling) have a ratio of about 5:1.
    Attached Images Attached Images
    Last edited by Solarfire; 10-12-2011 at 04:26.

  8. #388
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    Excellent! looking forward to getting my hands on a couple of these!

  9. #389
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    What an awesome product set!!!

  10. #390
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    May 2010
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    Perfect work !!! Iam searching for a TEC driver like that a long time. But theres one thing i miss. A Tec need more current for cooling than for heating. I think it would be better to control the current limit of heating and cooling individually. Iam also interested in 2 of these tec drivers.

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