Low Oil Presure Buzzer

[Wbulk]

I am going to add a low oil presure buzzer and a red warning light to my car. I want the buzzer to only work during low oil presure, but not when I have not started the car with the key is in the run position. I don't want to hear the buzzer every time I start the car until I have oil presure. Yes, there are advantages to hearing it every time until the oil presure is built up.

Anyone have experience with this set up.
Thanks.
Wayne

[patrickt]

Originally Posted by Wbulk

I don't want to hear the buzzer every time I start the car until I have oil presure. Yes, there are advantages to hearing it every time until the oil presure is built up.

Anyone have experience with this set up.
Thanks.
Wayne

That's pretty easy to do. Just feed the buzzer through a 555 timer circuit. Adjust the timer for, say, a 10 second delay and the buzzer will then have 12v positive (but no ground) after 10 seconds. Then, if you lose oil pressure, the sender will provide the ground circuit to the buzzer and it will sound off. 555 timer circuits are really cheap. Here's one place to get them for about $15.
http://www.apogeekits.com/555_timer_module.htm

[Wbulk]

Would this install before the oil presure switch or before the buzzer. Not the oil gauge pressure switch, but the idiot light switch. Or maybe it should be between the ignition switch and the relay that controls both.
Good information. Thanks.
Wayne

[patrickt]

Originally Posted by Wbulk

Would this install before the oil presure switch or before the buzzer. Not the oil gauge pressure switch, but the idiot light switch. Or maybe it should be between the ignition switch and the relay that controls both.
Good information. Thanks.
Wayne

I would set the 555 up between the positive source that feeds either the relay or the buzzer itself. This assumes that the sender does nothing more than provide a ground when there is no pressure on it. The 555 in its simplest form is really nothing more than a "cup" that gets filled up and when it does get full it "spills" over the side, but instead of water it uses electrons.

[Wbulk]

OK, I think I will put it just before the buzzer. That way I can still have the red light work until presure builds up. Great!
Thanks.
Wayne

[patrickt]

Originally Posted by Wbulk

OK, I think I will put it just before the buzzer. That way I can still have the red light work until presure builds up. Great!
Thanks.
Wayne

Yep, if the idiot light is fed from before the timer, and the buzzer is fed after the timer, I think you'll have just what you want.

[patrickt]

For a little bit more you can buy a 3 second 12v time delay relay.
http://www.electronicsurplus.com/com...oduct_id=72590

[Gaz64]

A far simpler way is to run the red wire of the buzzer to the alternator warning lamp wire at the alternator, the black wire to the oil pressure switch wire.

Key on not running, gives you zero volts at the alternator warning wire hence the alt warning lamp is on, oil buzzer will be off.

Engine running with oil pressure, 12 volt at the alt warning wire, alt lamp off, no earth at the oil pressure switch, buzzer off.

Engine running no oil pressure, 12 volt at the alt warning wire, earth at the oil pressure switch, buzzer on.

[trularin]

Gaz64 has a good inexpesive solution. The stator ( wire on alternator ) will be in the hole until the car is running. But, it will be biased at about 6 - 10 V as the alternator is charging.

Should be loud enough to hear it over your pipes!!!

I'd be interested to know what you come up with.

[patrickt]

Originally Posted by trularin

Gaz64 has a good inexpesive solution.

Two reasons why that might not be such a swell idea. 1) The idiot light circuit also feeds the the voltage regulator (through the filament or an optional resistor) in order to intiially excite it. If you add a buzzer circuit over on that side it may provide a better path to ground and the VR will not get initiated and the charging system will fail. 2) If there is sufficient current travelling through the filament (or the optional resistor) the buzzer might have a constant low level "zzzzzzzzzz" sound when the key is on, but the engine is not running.

[Gaz64]

Originally Posted by patrickt

Two reasons why that might not be such a swell idea. 1) The idiot light circuit also feeds the the voltage regulator (through the filament or an optional resistor) in order to intiially excite it. If you add a buzzer circuit over on that side it may provide a better path to ground and the VR will not get initiated and the charging system will fail. 2) If there is sufficient current travelling through the filament (or the optional resistor) the buzzer might have a constant low level "zzzzzzzzzz" sound when the key is on, but the engine is not running.

I have operated a relay for remote start from the alternator warning wire and never had an issue with the charging system. A diode in series with the relay coil prevents any backfeed.

A 12v buzzer is a high impedance in the forward direction compared to the regulator circuit and should not affect its' operation.

[Bill Bess]

Buzzers are a good idea, but I don't thing I could hear the darn thing in my car when the engine is running.
Remember, I'm old and can't always hear things..so I'll stick to the gauges.
Bill

[CowtownCobra]

A buzzer seems somewhat redundant. When I encountered low oil pressure on a road course with my first engine I was immediately alerted by large clouds of smoke and oil blowing out from under the hood, the side vents, under the car....

[Gaz64]

How about having a gauge AND a dual brightness LED warning lamp.

Normal brightness to match your other lamps at key on.

Super high brightness if engine running with low oil pressure.

A visual indicator in the corner of your eye will still win over a buzzer.

[Wbulk]

I'm convinced the buzzer in addition to the light is the way to go. A few seconds is the difference between a saved engine and hunk of junk.

I bought the buzzer today at Radio Shack. It's a Piezo 273-080, high instensity slow pulsing, 9-16 V, 300 frequency. It was about $6.00. It's an automotive warning buzzer. I think I will hear this buzzer over the pipes.

I also got an idiot light oil sender, small GM type, Car Quest #53-33508. I tapped into the oil sender tube by the oil filter on my 302, to put the new sender. This sender is grounded until the engine builds about 3-8 lbs. pressure and supplies the ground path for the light and the buzzer. So I have two senders, one for the gauge, the other for the light and buzzer. I'm still working on the wiring. I'm considering the 555 timer module, but am not sure about the wiring, or may use a time delay relay or a time delay switch.

My intention is to set the timer at about 2-3 seconds so the buzzer does not come on when I first start the car, but the light will be on a few seconds until pressure builds.
Thanks.
Wayne

[trularin]

Well, I do have a 1965 Ford wiring diagram.



Notice the S connection on the regulator goes off to the harness connected to the interior. As I recall, it was connected to the charging light.

I have used it before, didn't have any problems.

[slithering]

I wired the low oil pressure sensor to a relay, when pressure is made the relay closes and becomes the permissive start of my fuel pump. Should I lose oil pressure, I also lose fuel pressure.

[patrickt]

Originally Posted by trularin

Well, I do have a 1965 Ford wiring diagram.

Dang, that's something I would of done....

[Roscoe]

If you have Autometer electric gauges they used to make a device called 'Tri-Alert'.
You could setup any three gauges for either sound, light or both. I set mine up with a
dash light and a light that looks like a small shift light on top of the dash. This one is
removable as I only use it on the track.

I set up for high water temp, high oil temp and low oil pressure.

[Wbulk]

I found the instructions for the Tri-Alert. Great product, but it looks like it was discontinued. Now I am looking at a product called an Audio Oil Presure Alert Relay.
Wayne