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The dirt and easy way is as you suggest....a ceramic cased resistor suited to the wattage level you are working on. Not very efficient.
More effiecient, is to use a PWM IC...choose your poison, they all do the same and require minimal parts.
Just look up on the web for dc buck converter pwm
...as an aside, an old ATX computer power supply has one of those PWM and the Fets and everything else you need, even the correct inductors...love those units for parts
More effiecient, is to use a PWM IC...choose your poison, they all do the same and require minimal parts.
Just look up on the web for dc buck converter pwm
...as an aside, an old ATX computer power supply has one of those PWM and the Fets and everything else you need, even the correct inductors...love those units for parts
The resistor alone does not guarantee 35V. As the load fluctuates, so will the voltage.
What part number is your stepper motor driver. I've seen some that work on a wide range of voltages. Check the specs on that or give us the part number and can check the specs.
One way to lower a voltage is a zener diode and resistor. Find one that is as close to 35 V as possible. I'll leave the calculations to you, or see the following link
http://www.electronics-radio.com/articles/electronic_components/diode/zener-diode.php
What part number is your stepper motor driver. I've seen some that work on a wide range of voltages. Check the specs on that or give us the part number and can check the specs.
One way to lower a voltage is a zener diode and resistor. Find one that is as close to 35 V as possible. I'll leave the calculations to you, or see the following link
http://www.electronics-radio.com/articles/electronic_components/diode/zener-diode.php
ok, so the maximum voltage is 35V. I'd remain somewhat below that just to allow a safety margin.
I suggest a 30V or 33V zener and a good size electrolytic capacitor in parallel.
You may have to experiment with the resistor value and the power rating. I assume the stepper motor doesn't draw any current when not in motion. the power rating of your resistor will depend on movement/idle ratio.
Another idea is to build a simple 50% duty cycle high side transistor switch. the capacitor will average the voltage to 24V. Hope this helps
use about 60 - 70% duty cycle
I suggest a 30V or 33V zener and a good size electrolytic capacitor in parallel.
You may have to experiment with the resistor value and the power rating. I assume the stepper motor doesn't draw any current when not in motion. the power rating of your resistor will depend on movement/idle ratio.
Another idea is to build a simple 50% duty cycle high side transistor switch. the capacitor will average the voltage to 24V. Hope this helps
use about 60 - 70% duty cycle
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The problem you may have is that the DC resistance menas that about 10A will flow through each winding at 35V. This may be well in excess of the maximum for the motor.
The 35V may only be valid in certain situations where the PWM is used and the frequency is such that a higher voltage (35V) is required to allow the current through the winding to ramp up fast enough to its working value (it may be 2A - say). Applying 35V continuously may cause smoke to come out.
Without the specs on the stepper, this is just a heads up.
I personally think it would be hard to underestimate the utility of a zener regulator in this environment. Its utility is likely to be very low. Of course, knowing the peak, average (and for a zener regulator, minimum) current requirements we simply can't say.
In theory you can place a 7V (or higher) zener in *series* with the input voltage, and have a shunt resistor to ground to allow a certain minimum current to flow, but you're (possibly) going to need a pretty high power Zener and it only drops the voltage, it doesn't regulate it at all. In this case a simple series regulator using a zener as its reference is likely to perform better.
The 35V may only be valid in certain situations where the PWM is used and the frequency is such that a higher voltage (35V) is required to allow the current through the winding to ramp up fast enough to its working value (it may be 2A - say). Applying 35V continuously may cause smoke to come out.
Without the specs on the stepper, this is just a heads up.
I personally think it would be hard to underestimate the utility of a zener regulator in this environment. Its utility is likely to be very low. Of course, knowing the peak, average (and for a zener regulator, minimum) current requirements we simply can't say.
In theory you can place a 7V (or higher) zener in *series* with the input voltage, and have a shunt resistor to ground to allow a certain minimum current to flow, but you're (possibly) going to need a pretty high power Zener and it only drops the voltage, it doesn't regulate it at all. In this case a simple series regulator using a zener as its reference is likely to perform better.
