Hello,
I'm hoping that someone here can help me out with a small circuit design issue. I'm an IC layout designer by trade and it's been 20 years since I attended tech school so I can't even claim to be rusty.
I'm working on controlling the spindle speed on my CNC mill. I have a speed control card that outputs a signal from 0-10VDC to tell the spindle motor controller how fast to turn the motor. The problem is that the spindle motor controller needs some voltage just to get the spindle turning, around .7 volts. So I really need 0-5V output to be .7-5.7V. The speed control card has a top end voltage adjustment, but there isn't any way to adjust the low end output. The speed control card uses a 12VDC single sided supply.
I thought that a non inverting summing op amp would do the trick. I built a circuit using the LM741 op amp but I've since realized that the LM741 was a bad choice. It wasn't designed to swing rail to rail so the lowest voltage I can get out of it is about 2V. I've attached a drawing of the schematic.
I either need to find another op amp that can swing 0-10v off of a 12v supply or come up with another solution. Can one of you help me out?
Thanks,
Chris
I'm hoping that someone here can help me out with a small circuit design issue. I'm an IC layout designer by trade and it's been 20 years since I attended tech school so I can't even claim to be rusty.
I'm working on controlling the spindle speed on my CNC mill. I have a speed control card that outputs a signal from 0-10VDC to tell the spindle motor controller how fast to turn the motor. The problem is that the spindle motor controller needs some voltage just to get the spindle turning, around .7 volts. So I really need 0-5V output to be .7-5.7V. The speed control card has a top end voltage adjustment, but there isn't any way to adjust the low end output. The speed control card uses a 12VDC single sided supply.
I thought that a non inverting summing op amp would do the trick. I built a circuit using the LM741 op amp but I've since realized that the LM741 was a bad choice. It wasn't designed to swing rail to rail so the lowest voltage I can get out of it is about 2V. I've attached a drawing of the schematic.
I either need to find another op amp that can swing 0-10v off of a 12v supply or come up with another solution. Can one of you help me out?
Thanks,
Chris
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