So... I have an electronic vacuum pump on a diesel vehicle because on it's own the engine does not generate enough vacuum to run the brakes. So, the pump is wired up to a relay that has a vacuum switch on the control side. When the switch gets to 22" of vacuum it shuts the relay off by interrupting ground on the control side. Ignition powers the 12V high of the control. Simple enough....
My switch is WAY too sensitive. It's just a mechanical diaphragm, so it has no deadband/hysteresis. I'm having a problem where the relay is clicking on and off rapidly when the switch makes the connection, the switch itself jutters, then the relay does which further makes the switch signal oscillate. After about 1-2 seconds of random on/off, the relay stabilizes.
The issues is that this is wearing out my relay extremely quickly (obviously). I think it's arcing initially, but that quickly leads to latching. I need some way of smoothing out the signal or otherwise debouncing. I'd like to accomplish this without a circuit board if possible as this is under the hood and I'd rather not have a hokey looking box, I wasn't the tech that did the original install, but I have to fix this in the most professional way possible. Whatever fix I can find, has to be solid for years - I do not want to see this vehicle here again.
I've considered a capacitor on the line, but mildly concerned about the initial draw and I'm not certain what value would be most appropriate. Is this something that a pass filter would be acceptable for? Maybe I need a few components and a transistor to debounce? Does anyone make a special relay or other part for this?
Here is what the scope of the signal normally coming to negative pressure looks like:
**broken link removed**
My switch is WAY too sensitive. It's just a mechanical diaphragm, so it has no deadband/hysteresis. I'm having a problem where the relay is clicking on and off rapidly when the switch makes the connection, the switch itself jutters, then the relay does which further makes the switch signal oscillate. After about 1-2 seconds of random on/off, the relay stabilizes.
The issues is that this is wearing out my relay extremely quickly (obviously). I think it's arcing initially, but that quickly leads to latching. I need some way of smoothing out the signal or otherwise debouncing. I'd like to accomplish this without a circuit board if possible as this is under the hood and I'd rather not have a hokey looking box, I wasn't the tech that did the original install, but I have to fix this in the most professional way possible. Whatever fix I can find, has to be solid for years - I do not want to see this vehicle here again.
I've considered a capacitor on the line, but mildly concerned about the initial draw and I'm not certain what value would be most appropriate. Is this something that a pass filter would be acceptable for? Maybe I need a few components and a transistor to debounce? Does anyone make a special relay or other part for this?
Here is what the scope of the signal normally coming to negative pressure looks like:
**broken link removed**