PWM booster

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rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

PWM booster

Post by rimai »

Ok, for those that are trying DIY kits/plain Arduino boards that have a 0-5V PWM signal, you probably got caught with the fact that the drivers use 0-10V PWM dimming signal.
What you need to boost the signal is an op amp working as a doubler that will double the voltage, turning the 0-5V into 0-10V.
Attached is the circuit schematic you can use.
Be sure to apply 12VDC into VEE or you won't have enough juice to boost the signal.
Attachments
booster.png
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Roberto.
GrundelGravy
Posts: 3
Joined: Sat Jun 14, 2014 11:11 pm

Re: PWM booster

Post by GrundelGravy »

Awesome diagram. If I wanted to have 4 seperate 10v pwm channels would I have to make one of these per channel (seperate 12v supply per channel)? Thanks
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: PWM booster

Post by rimai »

Yes, but you can use the same 12vdc power supply

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Roberto.
GrundelGravy
Posts: 3
Joined: Sat Jun 14, 2014 11:11 pm

Re: PWM booster

Post by GrundelGravy »

Thanks for the quick response. Just a few more questions I promise. I am using eagle CAD and as you can tell I am fairly new to all this. What is SV1? Is that a 6 pin header? I changed it out for a 8pin RJ45 connector. Based on your diagram how would this, or where would the cabling go to the arduino? On the top where you have VEE with the 8 + 4 GND, I know the VEE is the input off the 12VDC power supply but what is that plus sign in the middle of the VEE and GND? I am guessing they are not connected together. Lastly, this calls for 2 LM358N's correct? Sorry for all the questions, I just want to get it right the first time, and your diagram seems to be the best thought out and clearer for me to understand.
Thanks again.
GrundelGravy
Posts: 3
Joined: Sat Jun 14, 2014 11:11 pm

Re: PWM booster

Post by GrundelGravy »

I made the board you posted. Thank you. I had a couple of questions. It seems I can drive 2 channels off of this 1 LM35 depending on the specs for my drivers. I ran the Fade sketch on the Arduino and the highest it goes is mid 8v's in the fading up and down. It will however go down to 0. Is this normal? I've wired a 12v power adapter to it and can trace the power throughout it, however during the sketch it maxes out at 8ish volts. I had trouble at first as it wouldnt go lower than 8 and realized I need ground coming from the Arduino so that allowed me to go to zero. During a test run in Fade in the example libraries in the Arduino, should I be able to go to 10v? Thank you.
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