Solenoid Interference any E.E. out there??
 

I'm playing with a heavy solenoid valve to give me two levels of boost. Works well, but when I deactivate the solenoid it screws with other electrical things ie; WBO2 hangs for a minute and resets. I have it on a completely different circuit. Can I hang a capacitor on the coil to stop this? What size and where??

Jefe? Kags? Anyone?

Hey, I was on Vacation!!!!
I would start with a 16vdc 22uf (electrolytic), between source and ground.
Also I'm curious why it would hang up your WBO2? Shared grounds? You might just need a diode on the ground wire of your circuit IN4001's are very pretty universal.
P.S. I found this while searching for coil springs...

I used to have this big old 'thing' in the garage I bought at crapshack when I was a kid to fix the static on my radio, it would have probably worked great..Oh yeah--it was called an inline noise suppressor.

Thanks. After months of using it, it still only affects the WBO2, it just freezes up for about a minute on the display and then goes back to normal.

So how does it work? I ass-u-me you can switch between 8 and 20psi?:bigtu:

Is it just the display that locks up? Or do you think the WBO2 controller stops as well?

8 and 16 psi actually(or wherever I set the Hallman). I really should datalog while I throw the switch off to see if it is only the display. It only happens when I turn the coil off. Turning it on affects nothing but boost rise. I use my WBO2 only for monitoring, not for any control.

Basically, with the solenoid deactivated the wastegate actuator receives the straight pressure signal. When the solenoid is activated, it channels the boost through the Hallman to the actuator which can be set anywhere I like above the pressure required to move the actuator. I call it my "go fast" button.

What circuit runs off the solenoid? What signals the solenoid? What is the other load which causes the voltage drop?

Solenoid is just triggered by a switch. It activates my hi-lo boost. When the solenoid deactivates, the surge knocks out my Zeitronix WBO2 (totally different circuit) for about 30 seconds

OK, this is actually a very different problem than Rob's.

When you deactivate a solenoid (assuming dc power), it creates a voltage spike, albeit very briefly. Apparantely this spike is making its way to your WB, which is either hyper sensitive or features a protection circuit.

Diode isolate the solenoid's power feed. That will prevent the solenoid from back feeding the spike. A neat way of doing this is to use LEDs. That way when the solenoid is activated, the LEDs will be lit. Get the diodes as close to the solenoid as possible.

In series with a solenoid?

Even if it only takes 100ma at 12V to operate the solenoid (and I'm pulling that number out of the air- it seems low to me) that's a paltry 120 ohms coil resistance. A big T1-3/4 red LED in the 1000mcd range is dropping maybe 2V at 20ma. I can't see how the math works out on this one.

Why not just reverse-bias a 1N400x part across the coil like you would a relay? And put the series diode in too if you want some extra protection- ain't gonna hurt anything.

Yes, in series with the solenoid, or the other option is to place the diode in parallel with the solenoid's contacts. Either or both will work to block the voltage created when the solenoid's magnetic field collapses.

I didn't do any of the math involved, I know OlderGuy is capable--I've read posts where he's schooled others regarding diodes and leds.

I just don't think putting an LED in series with the solenoid coil is gonna fly. The current requirement of the solenoid is going to be much higher than what the LED can pass, and the series resistance of the coil is going to be much lower than what the LED requires to operate at 12 volts. In other words, the LED will fail due to over-current, and then the solenoid won't operate due to the resulting open-circuit condition.

This trick works in other applications (like O2 clamps) where the current requirement is very low, but it's not gonna fly here. Put a traditional diode (like a 1N4004), reverse-biased, in parallel with the coil. The equivilant inductance of the supply wire leading up to the circuit will make the diode the path of least resistance assuming the ground is nice and short.

I'm not even sure if a second diode in series with the coil is going to accomplish anything, since the back EMF coming off the coil is gonna be a lot higher than the reverse breakdown voltage of a common silicon rectifier. Maybe something like a 10A07 with a huge VRRM, but the VF on these kind of parts can be pretty high, and I still think you'd need to stack a few in series to get meaningful rejection.

Agree completely. I never suggested using a single LED. I wrote "LEDs". And again, didn't do any math.

A quick websearch showed it to be fairly common in DIY circuits and effective for blocking inductive kickback.
I originally got the idea that Bruce's spike was caused by kickback after thinking about what happens when you remove power from a DC motor, and in such a circumstance a diode in series between the motor and power supply absorbs the kickback.

None the less, I defer to your obvious expertise in the area. I just install big stereos for a living. :bigtu:

Hopefully we've solved Bruce's problem.

How about runing the solonoid with a relay? There are even relays that are anti-flyback (diode allready installed)

The diode idea should work too imo


Ron