Electric Potato
Well-known member
Hey guys,
I've posting many tech support questions recently but I think this'll be the last of em for a while so thanks for putting up with me! I've got an HC385MG DC motor I pulled out of a printer http://webcache.googleusercontent.com/search?q=cache:jCPQJ-813ggJ:www.johnsonelectric.com/en/products/motion/dc-motors/standard-dc-motors/low-voltage-dc-motors/datasheets/HC385MG-020-metric.pdf+&cd=6&hl=en&ct=clnk&gl=us
I have it wired up as in this schematic: https://forum.pjrc.com/threads/1840-Controlling-a-pump-with-teensy3?highlight=tip120 (instead of an IN5817 I'm using a 1N4001, don't know if that matters)
I need it to run relatively slowly, around its top speed when attached to 3V, but sometimes a bit faster and slower. My goal is to run it off either 6V or 4.5V but probably never give it a full on PWM output of 255. It will run just fine at PWM write values of down to around 80 (it starts choking up below there) but the problem is that anything lower than 255 makes it start emitting a sawtoothy tone at 490 Hz, which gets louder as the PWM vaues get lower. If the motor stalls out totally (around and PWM write of 60) it just sits there emitting this tone loudly.
I don't have much experience working with motors and don't really have any idea what to do about it. The motor's in a case and I've tried muffling it a bit but it's still annoyingly loud. I'm sure there's a significance to the pitch of the tone but I got nothin
thanks for any help!
I've posting many tech support questions recently but I think this'll be the last of em for a while so thanks for putting up with me! I've got an HC385MG DC motor I pulled out of a printer http://webcache.googleusercontent.com/search?q=cache:jCPQJ-813ggJ:www.johnsonelectric.com/en/products/motion/dc-motors/standard-dc-motors/low-voltage-dc-motors/datasheets/HC385MG-020-metric.pdf+&cd=6&hl=en&ct=clnk&gl=us
I have it wired up as in this schematic: https://forum.pjrc.com/threads/1840-Controlling-a-pump-with-teensy3?highlight=tip120 (instead of an IN5817 I'm using a 1N4001, don't know if that matters)
I need it to run relatively slowly, around its top speed when attached to 3V, but sometimes a bit faster and slower. My goal is to run it off either 6V or 4.5V but probably never give it a full on PWM output of 255. It will run just fine at PWM write values of down to around 80 (it starts choking up below there) but the problem is that anything lower than 255 makes it start emitting a sawtoothy tone at 490 Hz, which gets louder as the PWM vaues get lower. If the motor stalls out totally (around and PWM write of 60) it just sits there emitting this tone loudly.
I don't have much experience working with motors and don't really have any idea what to do about it. The motor's in a case and I've tried muffling it a bit but it's still annoyingly loud. I'm sure there's a significance to the pitch of the tone but I got nothin
thanks for any help!
