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  #11  
Old 01-25-2013, 10:03 PM
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Here is how I did it... advancing the hours on a digital tach. This tach (Faria) reads actual engine running hrs. and requires the tach signal to advance.

Last edited by setidball; 01-26-2013 at 10:30 AM.
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  #12  
Old 06-10-2013, 11:17 PM
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setidball is there a layman's way of explaining that? Maybe pics or parts you used and the setup, where you got them, etc. I'm no electrical genius, but do have a desire to get this digital hour meter right.
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Old 06-11-2013, 07:32 PM
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I can try. I’m just a backyard “hack” with electronics so I’m sure there are other ways, perhaps simpler, to advance a digital hr meter and it probably depends on the meter. The modern digital meter does not advance simply with a 12v supply. It needs an actual tach signal from the engine. I called the manufacture of the tach/hr meter and asked their tech, what signal shape and voltage the hr meter was looking for.
My circuit does not exactly mimic what I was told but it was close enough to work.

The schematic in the picture is a basic “timer” or “clock” circuit. The heart of it is an IC chip called a “555 timer” and is readily available at Radio Shack or any other electronics supply store. C1, C2, C3, R1, and R2 are Capacitors and Resisters used to set the output of the timer to any particular frequency. The tables just indicate the values of the capacitors and resisters to achieve a frequency (simulated rpm of the engine). I used the values as shown on the schematic. The speaker was there just so I could tell it was working. I assemble the circuit on an electronics “bread board” also available at Radio Shack.

The circuit will run on a 12 volt power supply and output approximately the correct signal amplitude.

Once you get the hr meter running, set an alarm clock for yourself to turn it off. They don’t go backwards. S
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  #14  
Old 06-11-2013, 07:55 PM
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Originally Posted by setidball View Post
I can try. I’m just a backyard “hack” with electronics so I’m sure there are other ways, perhaps simpler, to advance a digital hr meter and it probably depends on the meter. The modern digital meter does not advance simply with a 12v supply. It needs an actual tach signal from the engine. I called the manufacture of the tach/hr meter and asked their tech, what signal shape and voltage the hr meter was looking for.
My circuit does not exactly mimic what I was told but it was close enough to work.

The schematic in the picture is a basic “timer” or “clock” circuit. The heart of it is an IC chip called a “555 timer” and is readily available at Radio Shack or any other electronics supply store. C1, C2, C3, R1, and R2 are Capacitors and Resisters used to set the output of the timer to any particular frequency. The tables just indicate the values of the capacitors and resisters to achieve a frequency (simulated rpm of the engine). I used the values as shown on the schematic. The speaker was there just so I could tell it was working. I assemble the circuit on an electronics “bread board” also available at Radio Shack.

The circuit will run on a 12 volt power supply and output approximately the correct signal amplitude.

Once you get the hr meter running, set an alarm clock for yourself to turn it off. They don’t go backwards. S
Why not use a signal generator and vary the frequency so it can be watched, to avoid advancing too far? Plenty of free programs are available and some can be varied in 1Hz increments.
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  #15  
Old 06-11-2013, 08:19 PM
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Why not use a signal generator and vary the frequency so it can be watched, to avoid advancing too far? Plenty of free programs are available and some can be varied in 1Hz increments.
Absolutely!! If you have a sig gen available that would be super easy. I don't have a sig gen but I did have all the components to make one. Frequency only maters in that it must be greater than the equivalent of 400ish rpm. A faster rpm does not advance the hr meter faster but the tach/meter must believe the engine is running ... so, idle or above. S
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  #16  
Old 06-11-2013, 09:12 PM
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Originally Posted by setidball View Post
Absolutely!! If you have a sig gen available that would be super easy. I don't have a sig gen but I did have all the components to make one. Frequency only maters in that it must be greater than the equivalent of 400ish rpm. A faster rpm does not advance the hr meter faster but the tach/meter must believe the engine is running ... so, idle or above. S
What "make"? TrueRTA and RoomEQ Wizard are free programs that have signal generators and in the case of TrueRTA, you can choose sine, square, triangle and sawtooth wave forms. You just need to interface the output with the tach.
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  #17  
Old 06-11-2013, 10:21 PM
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That makes a whole lot more sense. I think I can get somewhere now. Thanks alot!
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  #18  
Old 06-12-2013, 12:35 AM
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Originally Posted by JimN View Post
What "make"? TrueRTA and RoomEQ Wizard are free programs that have signal generators and in the case of TrueRTA, you can choose sine, square, triangle and sawtooth wave forms. You just need to interface the output with the tach.
Hum, I don't know anything about these programs. It appears that the output amplitude is indicated in dB's.... which should be fine if you know what the equivalent voltage amplitude is. The tach/hr meter is looking for a minimum frequency with in a 5 to 12 volt amplitude. And you need some way to output that to the tach.

Quote from the Faria tech: "It is a sine wave. You need at least a 5 volt signal. When the tach pointer is over 500 rpm it starts counting. 50 - 100 Hz should work."

My 555 circuit is more of a sawtooth but it worked. S
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