Electronics > Projects, Designs, and Technical Stuff
Generator Auto Start - When to Stop Cranking
tautech:
--- Quote from: frostheave on February 08, 2019, 09:49:57 pm ---I want to make the system as idiot proof as possible!
--- End quote ---
IMO a microswitch on the governor throttle linkage somewhere could be the way to go if you're prepared to do a little experimentation and metalwork for a bracket on which to mount it.
The governor won't move at cranking speeds but it will immediately on engine firing as the RPM's lift.
Take a moment to observe its behavior then decide if it will suit your needs.
I'd probably cascade the microswitch into a small 12V relay which then breaks the starter solenoid winding.
Old school I know but you won't need to worry about needing any snubbers controlling the back EMF from the solenoid winding that might fry semiconductor switching of the solenoid.
Still you might need a reverse bias diode on the small 12V relay winding as this is where you'd likely switch in for when mains power fails.
frostheave:
--- Quote from: Bratster on February 08, 2019, 10:24:32 pm ---
--- Quote from: frostheave on February 08, 2019, 09:59:11 pm ---
Thanks NorthGuy.
Nothing fancy about the gen. I will be using an Arduino for the controls. Is there some advantage to monitoring frequency vs. voltage?
--- End quote ---
If this is a basic generator, frequency will be very strictly tied in with RPM.
I'm guessing the generator running RPM will probably be 3600 for 60 Hertz.
That's what the ones that I have installed at various sites are.
Sent from my Fi Moto x4 using Tapatalk
--- End quote ---
AH HA, I see.
I wonder if it is linear, i.e. the frequency would increase 1Hz for every 60 rpm increase.
Thanks for the insight.
frostheave:
--- Quote from: tautech on February 08, 2019, 10:52:29 pm ---
--- Quote from: frostheave on February 08, 2019, 09:49:57 pm ---I want to make the system as idiot proof as possible!
--- End quote ---
IMO a microswitch on the governor throttle linkage somewhere could be the way to go if you're prepared to do a little experimentation and metalwork for a bracket on which to mount it.
The governor won't move at cranking speeds but it will immediately on engine firing as the RPM's lift.
Take a moment to observe its behavior then decide if it will suit your needs.
I'd probably cascade the microswitch into a small 12V relay which then breaks the starter solenoid winding.
Old school I know but you won't need to worry about needing any snubbers controlling the back EMF from the solenoid winding that might fry semiconductor switching of the solenoid.
Still you might need a reverse bias diode on the small 12V relay winding as this is where you'd likely switch in for when mains power fails.
--- End quote ---
Now that is a very interesting idea. I like it.
Unfortunately, I am working away from home for the next 2 weeks so I won't be able to try these great options until I get back.
Thanks for the KISS idea.
tautech:
--- Quote from: frostheave on February 08, 2019, 11:47:18 pm ---
--- Quote from: tautech on February 08, 2019, 10:52:29 pm ---
--- Quote from: frostheave on February 08, 2019, 09:49:57 pm ---I want to make the system as idiot proof as possible!
--- End quote ---
IMO a microswitch on the governor throttle linkage somewhere could be the way to go if you're prepared to do a little experimentation and metalwork for a bracket on which to mount it.
The governor won't move at cranking speeds but it will immediately on engine firing as the RPM's lift.
Take a moment to observe its behavior then decide if it will suit your needs.
I'd probably cascade the microswitch into a small 12V relay which then breaks the starter solenoid winding.
Old school I know but you won't need to worry about needing any snubbers controlling the back EMF from the solenoid winding that might fry semiconductor switching of the solenoid.
Still you might need a reverse bias diode on the small 12V relay winding as this is where you'd likely switch in for when mains power fails.
--- End quote ---
Now that is a very interesting idea. I like it.
Unfortunately, I am working away from home for the next 2 weeks so I won't be able to try these great options until I get back.
Thanks for the KISS idea.
--- End quote ---
:)
Sometimes we just overlook the piss simple remedies. ;)
As to just how to use a microswitch, well you could just let the governor arm press against it or use a pull type and connect it to the arm with a linkage or light spring.
In either case you need enough travel and force to activate the switch without influencing the governor arm unduly so that it effects how it controls engine RPM, that BTW as mentioned is normally 3600 or just a shade more to manage loads and maintain correct mains frequency.
den:
Current sensing coil on the high-voltage spark plug wire would do a good job making an RPM signal. One could use a Schmitt trigger to convert the signal to a digital form. Small bonus: if ignition fails - you do not fill you crankcase with fuel, trying to start the engine.
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