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  1. #1
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    how to increase voltage

    Hi! I'm new to electronic design and I can't find out well. I have one simple task. Microcontroller produces PWM (10Hz-1000Hz) duty cycle can vary from 10% to 90%. This is not a problem because I am more programmer than electronic engineer. But that signal should be amplified in some way so I can get from 5V-45V voltage and current not more than 100mA. Is there any similar scheme that I can implement. Should I use transformer or it can be done without it.
    Thanks in advance.

    •   Alt1st October 2007, 19:38

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    increase voltage

    Hi binary2007,

    Well, if you want to get up to 45 V from your 5 volts PWM source, you can always use an OP AMP and fix its gain to 9, ( u can manage to put a little pot in the feedback loop of the AMP for fine adjesting later on ). concerning the current a simple transistor will do the job. I recommend using a feedback of your output wich you will connect to your controller if this latter have any A/D converter, such a feedback will allow you to exactly match the request output voltage.
    If this is what you're looking for i can draw a little schematic of the Idea.

    Hope this Helps,

    Hassen.


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    increase voltage circuit

    You can use a level shifter IC.



    •   Alt2nd October 2007, 11:45

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    how to increase voltage output

    Hi hassenman!

    I would appreciate you draw me that scheme. Thank You. I think that might solve my problem.



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    voltage increase

    I wouldn't use an op-amp for this, you have slew rates etc to worry about.

    Look for an Open-Collector Buffer which will support an output of 45V, the data sheet will give you the the info you need to know to configure it. The chip will only require an external resistor.



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    how do you increase voltage

    Hi !!!

    If you want to learn a little bit of analogic electronic, you could use transistors, and some resistors.
    You could easily find a transistors which accept voltage of 45V and 100mA of current.

    If your load doesn't need to be referenced to GND, you could use only one NPN transistor. But if your load need to be connected to GND, you shoud use 2 transostor : one PNP as a switch between your load and the 45V, and one NPN to produce the correct voltage command for the PNP.
    I could send you the schematic if you want.
    Bye !!!



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    how to increase volt

    Hi binary2007,

    i'm sorry for the delay, i included here a part of a circuit i used lately.

    i'm assuming here that u already got your 0 -- 5 volts pwm working and you already filtered it.

    You will use the filtered PWM signal and amplify it with this AMP op based circuit. First thing to carry about is the use of a high voltage AMP OP ( 45 volts at least ).
    I think Slew rate won't be a problem to your design since you're dealing with already stabilized voltage, slew rate would be benificial to your signal if it's still fluctuating .
    The use of the Q1 transistor will allow u to reach the sighted amount of current, while Q2 with Re1 will prevent short circuits.
    Of course, u'll have to choose the proper values to your components, making sure AMP op Gain is 9 ( the pots in the feedback loop will allow u to ajust that gain exactly to the requested value ...).
    Now when everything is working ok , you will have to measure the output of your design through an A/D converter ( assuming that your controller already got one ).
    with that u'll be able through your software to exactly match any requested voltage by adjusting duty cycle of your PWM signal . . .

    This is the way i see it :) . . .

    Hope this helps,
    Hassen.



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    voltage increaser

    This is the solution



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