Re: Re: Which Oil Pressure Switch?


Subject:    Re: Re: Which Oil Pressure Switch?
From:    M Wilson (mike_tailwind@yahoo.com)
Date:    Tue Mar 26 - 9:26 AM
 You could modify Bob's latest overvoltage module to do what you need.=C2
- Change the trip point to 13.5 volts, and remove the SCR.
>From schematic 9003-630-IP6:Change R7 from 13.7K to 11KRemove Q15Add a wire
 from U11B pin 7 to the enable input=C2- of the hour meter.
What we don't know is how much current the enable input to the hour meter d
raws.=C2- To test, place a 2.49K resistor between the enable input of the
 hourmeter and 12Volts.=C2- If it starts counting, no additional changes 
to the OVM need to be made.=C2-=C2-


    On Tuesday, March 26, 2024 at 08:34:33 AM CDT, Mudfly <shawntedwards@ho
tmail.com> wrote:  

om>

I've been away from electrical work on my project while I installed 
engine and related accessories.=C2- 
I'm reviving this thread on ways to activate a hobbs meter without 
using an oil pressure switch.=C2- I have an LED hobbs meter that I would
like to wire so that it will display the hours when the batt switch is on ,

but not count time.=C2- I would like the timer to begin when engine is st
arted.
As a review from the previous threads above, I have a 3-terminal 
hobbs (+, -, and Enable).=C2- =C2- The positive terminal is fed from th
e Main Power Bus when batt is switched, and negative to firewall ground bus
. The LED 
digits illuminate with Batt switch on.=C2- I now need a way to power the
Enable terminal to begin the timer.=C2- 
I have an idea but not sure of the part I need or if it even exists.
Here the plan.=C2- The positive terminal will have the 12v input from the
 main power bus.=C2- Also, I will have a feed wire from the positive term
inal to 
the "Unknown Device".=C2- The wire will continue from the unknown 
device to the Enable pin on the hobbs meter.=C2- =C2- The "Unknown Devi
ce" 
will need to block power until volts are above batt voltage..
say 13V??.=C2- When the engine is started and alternator is switched on,

power will pass the unknown device and power the enable terminal of the 
hobbs meter.=C2- =C2- 
Does this "Unknown Device" exist, and does the plan seem feasible?
Links to PDF drawings of a simple wire diagram and also tech sheet of the

Honeywell LCD Hour meter.
Thanks for the help.
Shawn


Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=513410#513410


Attachments: 

http://forums.matronics.com//files/honeywell_lcd_hour_meter_173.pdf
http://forums.matronics.com//files/hobbs_meter_117.pdf


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S -
WIKI -
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=C2- =C2- =C2- =C2- =C2- -Matt Dralle, List Admin.




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