Hello all,
I work with a couple of friends at a mill. I run the hammer mill area: 150hp motor driving the mill, auger motors and feeders and the like... very low tech.
Recently, thanks to a fire, I lost my single phase 3 hp feed auger motor. I had to get some work done, so i wired up a 5hp 3 phase motor in its place. I though this would be great, more power and more reliability (I was always repairing the 1 phase motor due to dust intrusion - yes it was sealed... lot of dust).
Well, I have plenty of power - so much so i blow through belts like no tomorrow.By the time I see the system is jammed the motor has pretty well chewed through my double, B52 belts.
I tried to limit the current using a thermal over load relay (TK-E02-900) but even though I have t set to well below the motor's rating, it never trips - I believe its due to the fact the system never gets to static friction and stays kinetic...
So, I wanted to design a wheel sensor motor. One that would light and buzz when the wheel stops.
I was going to use:
1) a magnet/coil to generate a signal (magnet glued to wheel, stationary coil).
2) signal from coil to drive a transistor or opamp to amplify that signal
3) Send amplified signal to a timer re-set.
4) allow timer to trigger the lights and noise makers if not re-set in time.
But alas, I cant get the coil / magnet to trip the transistor. (my op amp just sat at +rail, so i moved to a simple transistor). If I open the coil leg and touch the leg a signal is amplified and my LED (stand-in for down stream circuitry to be designed later) it lights up just fine.
Am I asking too much of the coil? Is there really that little v/a in a coil excited by a magnet? I must be doing something stupid... I can measure only 1.6mv when I pass the magnet past the coil.
I attached a simple drawing, but its a simple LED driving circuit.
I am open to ideas / circuits I could build. I'm not married to my idea, I just want to get some work done without burning up belts.
I work with a couple of friends at a mill. I run the hammer mill area: 150hp motor driving the mill, auger motors and feeders and the like... very low tech.
Recently, thanks to a fire, I lost my single phase 3 hp feed auger motor. I had to get some work done, so i wired up a 5hp 3 phase motor in its place. I though this would be great, more power and more reliability (I was always repairing the 1 phase motor due to dust intrusion - yes it was sealed... lot of dust).
Well, I have plenty of power - so much so i blow through belts like no tomorrow.By the time I see the system is jammed the motor has pretty well chewed through my double, B52 belts.
I tried to limit the current using a thermal over load relay (TK-E02-900) but even though I have t set to well below the motor's rating, it never trips - I believe its due to the fact the system never gets to static friction and stays kinetic...
So, I wanted to design a wheel sensor motor. One that would light and buzz when the wheel stops.
I was going to use:
1) a magnet/coil to generate a signal (magnet glued to wheel, stationary coil).
2) signal from coil to drive a transistor or opamp to amplify that signal
3) Send amplified signal to a timer re-set.
4) allow timer to trigger the lights and noise makers if not re-set in time.
But alas, I cant get the coil / magnet to trip the transistor. (my op amp just sat at +rail, so i moved to a simple transistor). If I open the coil leg and touch the leg a signal is amplified and my LED (stand-in for down stream circuitry to be designed later) it lights up just fine.
Am I asking too much of the coil? Is there really that little v/a in a coil excited by a magnet? I must be doing something stupid... I can measure only 1.6mv when I pass the magnet past the coil.
I attached a simple drawing, but its a simple LED driving circuit.
I am open to ideas / circuits I could build. I'm not married to my idea, I just want to get some work done without burning up belts.