Hour Meter Type

by Ted Norris in General Tech Discussion 13 years ago

My plane doesn't have a hour meter and I want to put one on it, the choices are analog or digital, 12v powered and lithium battery powered. I transport it in a trailer, I would like to be able to work on it with 12v power on which would activate a 12v powered unit and a lithium battery vibration unit would be activated while transporting it. What's the wisdom of the forum on which way to go or what to do .

Ted

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Re: Hour Meter Type

by Kevin Stewart » 13 years ago

Kevin Stewart

5 184 0

I use a 12V analogue type which is only energised when the engine oil pressure goes above 1 Bar. It works well.

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Re: Hour Meter Type

by Ted Norris » 13 years ago

Ted Norris

22 47 0

Do you have a make on that type of meter, I've looked and haven't seen one with that function.

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Re: Hour Meter Type

by Kevin Stewart » 13 years ago

Kevin Stewart

5 184 0

I used one like this:

http://stores.worldavionics.net/-strse-684/85012/Detail.bok

and then built a small circuit to do the oil pressure detection (see attached PDFs).

I have also attached a file that can be printed out and stuck to the top side of a piece of Vero strip board to show where to fit the components.

There is also a diagram showing where to cut the tracks underneath.

To adjust the trip point of the circuit you need to fit a variable resistor in place of your oil pressure sender and then adjust it so that your gauge reads 1 Bar. Then adjust the preset on the circuit so that the LED comes on. Don't forget to reconnect the oil pressure sender when you're finished! The Hobbs connects between +12V & the Hobbs -ve terminal of the circuit.

I have been using this circuit successfully for a number of years. As a later mod I added a small piezo buzzer across D1, this then acts as a warning so that you don't accidentally leave your master on and drain your battery ;-) This latter function may not work if you use a low current digital type Hobbs.

I have a vague recollection that I have seen a Hobbs with a built in oil pressure sense circuit. If I find it I will post details.

Hobbsswitch-C.pdf (You do not have access to download this file.)

HobbsswitchSilkScreen-B.pdf (You do not have access to download this file.)

Hobbsswitchlayout-B.pdf (You do not have access to download this file.)

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Re: Hour Meter Type

by Ted Norris » 13 years ago

Ted Norris

22 47 0

I found this :
http://www.vansaircraft.com/cgi-bin/catalog.cgi?ident=1258455059-52-60&browse=ei&product=isspro-hour

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Re: Hour Meter Type

by Kevin Stewart » 13 years ago

Kevin Stewart

5 184 0

As Ted has indicated you can of course use a separate oil pressure switch to control any 12V powered Hobbs meter. I did consider this option but didn't fancy any additional plumbing in the oil circuit given that there was already a pressure transducer.

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Hour Meter Type

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