2020-07-23, 07:54 PM
(2020-07-23, 03:32 PM)johnm Wrote: purchased a used octopus 1212lar12.I second this request! The Octopus clutch isn't designed to have constant power. It just needs momentary power to engage the clutch and then the power is not needed. This is actually a safety issue. When the clutch is engaged and the power is off a quick jerk of the wheel releases the clutch. With the power on all the time the clutch will not release making manual steering impossible.
Will not install until spring but tested to make sure it works.
I propose pwm the clutch output after an initial full power pulse for about 100ms.
Holding the clutch at full power waists a lot of power.
It's hot enough that it could be a burn hazard and possibly damage the coil.
For this clutch these are my measurements:
coil 10 ohms
full: 12.57v 1.11a
drops out: 1.27v 0.1a Needless to say want to stay well above the drop out point.
kicks in at 6.83v 0.6a
Way back when I serviceed equipment with large solenoids they always had a resistor and capacitor paralleled in series with the power. That will work but pwm will save even more power.
From searching a couple additional ideas I found:
Periodically give a full pulse just in case it dropped out.
Probably should have small capacitor across output to keep down rf noise.
The inductance will rise considerably when engaged. The surge current will be much less if engaged so one can sense if the clutch is engaged by measuring the current. Interesting but probably overkill and would need setup an another analog input.